*{box-sizing:border-box}:root{--bg:#f4f7fb;--panel:#fff;--text:#172033;--muted:#667085;--line:#dfe5ef;--primary:#635bff;--primary2:#5149df;--good:#07883f;--bad:#c93636;--code:#121827;--codeText:#dbe7ff;--shadow:0 10px 30px #20304a12}body.dark{--bg:#0e1420;--panel:#171f2e;--text:#eaf0fa;--muted:#9facbf;--line:#2b374b;--shadow:0 10px 30px #0005}html,body{margin:0;height:100%;font-family:"Source Sans 3","Noto Sans TC",system-ui,sans-serif;background:var(--bg);color:var(--text)}button,label.file{font:inherit;border:0;cursor:pointer}.hidden{display:none!important}header{height:64px;background:var(--panel);border-bottom:1px solid var(--line);display:flex;align-items:center;padding:0 18px;position:sticky;top:0;z-index:20}.brand{display:flex;align-items:baseline;gap:10px}.brand b{font-size:21px;color:var(--primary)}.brand span{font-size:13px;color:var(--muted)}.header-actions{margin-left:auto;display:flex;gap:9px;align-items:center}.layout{display:grid;grid-template-columns:270px 1fr;min-height:calc(100vh - 64px)}aside{background:var(--panel);border-right:1px solid var(--line);padding:18px;position:sticky;top:64px;height:calc(100vh - 64px);overflow:auto}.progress-box{background:var(--bg);padding:14px;border-radius:12px;margin-bottom:18px}.progress-box>div:first-child{display:flex;justify-content:space-between}.progress-box small{color:var(--muted)}.bar{height:7px;background:var(--line);border-radius:9px;margin:10px 0}.bar i{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--primary),#24b7ff);border-radius:9px;transition:.3s}nav h4{color:var(--muted);font-size:12px;margin:18px 8px 7px}nav button{display:flex;width:100%;text-align:left;padding:10px;border-radius:9px;background:transparent;color:var(--text);gap:8px}nav button:hover,nav button.active{background:var(--bg);color:var(--primary)}nav button.done .dot{background:var(--good)}.dot{width:9px;height:9px;margin-top:6px;border:2px solid var(--line);border-radius:50%}main{padding:35px clamp(18px,4vw,64px);max-width:1500px;width:100%;margin:auto}.lesson-head,.practice-head{display:flex;justify-content:space-between;gap:24px;align-items:flex-start}.lesson-head h1,.practice-head h1{font-size:34px;margin:8px 0}.lesson-head p,.practice-head p{color:var(--muted);max-width:800px;line-height:1.7}.tag{font-size:12px;color:var(--primary);font-weight:700;background:#635bff16;padding:5px 9px;border-radius:99px}article{font-size:16px;line-height:1.8}article h2,section h2{margin-top:35px}article code{background:var(--line);padding:2px 6px;border-radius:5px;color:var(--primary)}article .callout{border-left:4px solid var(--primary);padding:12px 16px;background:var(--panel);border-radius:0 9px 9px 0}.token-code{background:var(--code);color:var(--codeText);padding:20px;border-radius:12px;white-space:pre-wrap;line-height:1.8;box-shadow:var(--shadow)}.tok{cursor:pointer;border-radius:4px;padding:1px}.tok:hover{outline:1px solid white}.tok.keyword{color:#ff79c6}.tok.string{color:#f1fa8c}.tok.number{color:#bd93f9}.tok.operator{color:#8be9fd}.tok.name{color:#50fa7b}.explain-card{background:var(--panel);border:1px solid var(--line);padding:16px;border-radius:11px;min-height:74px}.explain-card b{color:var(--primary)}.pager,.practice-nav{display:flex;justify-content:space-between;margin-top:32px}.primary,.secondary,.danger{padding:9px 14px;border-radius:8px}.primary{background:var(--primary);color:white}.primary:hover{background:var(--primary2)}.secondary{background:var(--panel);border:1px solid var(--line);color:var(--text)}.danger{background:var(--bad);color:white}.ghost{background:transparent;color:var(--bad);width:100%;margin-top:20px}.icon-btn{background:transparent;color:var(--text);font-size:20px;padding:8px}.pill{font-size:12px;padding:5px 9px;border-radius:99px;background:#07883f18;color:var(--good)}.pill.wait{background:#b8750018;color:#b87500}.file input{display:none}.muted{color:var(--muted)}.workbench{display:grid;grid-template-columns:1fr 1fr;gap:16px}.editor-wrap,.result-wrap{background:var(--panel);border:1px solid var(--line);border-radius:12px;overflow:hidden;min-height:470px}.editor-top,.runbar,.tabs{height:44px;padding:0 12px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);font-size:12px;color:var(--muted)}textarea{display:block;width:100%;height:370px;resize:none;border:0;outline:0;background:var(--code);color:var(--codeText);padding:18px;font:15px/1.65 ui-monospace,SFMono-Regular,Consolas,monospace;tab-size:4}.runbar{border-top:1px solid var(--line);border-bottom:0;justify-content:flex-start;gap:9px}.tabs{justify-content:flex-start;padding:0}.tab{height:100%;background:transparent;color:var(--muted);padding:0 15px}.tab.active{color:var(--primary);border-bottom:2px solid var(--primary)}.panel{margin:0;padding:18px;height:425px;overflow:auto;white-space:pre-wrap;font:14px/1.6 ui-monospace,monospace}.result-wrap .panel:not(pre){font-family:inherit}.ok{color:var(--good)}.fail{color:var(--bad)}.diagnosis{border-left:4px solid var(--bad);background:#c9363610;padding:13px;border-radius:8px;margin-bottom:10px}.hint{padding:14px;background:#b8750015;border:1px solid #b8750040;border-radius:9px;margin-bottom:16px}.toast{position:fixed;right:20px;top:78px;background:#172033;color:white;padding:10px 16px;border-radius:8px;z-index:99;opacity:0;transform:translateY(-10px);transition:.25s;pointer-events:none}.toast.show{opacity:1;transform:none}kbd{background:var(--line);padding:2px 5px;border-radius:4px}@media(max-width:900px){.layout{grid-template-columns:1fr}aside{position:fixed;left:-290px;z-index:30;width:270px;transition:.25s;box-shadow:var(--shadow)}aside.open{left:0}.workbench{grid-template-columns:1fr}.header-actions .secondary{display:none}.lesson-head,.practice-head{display:block}.lesson-head>button{margin-bottom:15px}main{padding:24px 15px}}
/* Premium Learning UI v2.1.3 — Ink Notebook */
:root{--bg:#F3F1EC;--panel:#FFFcf8;--panel2:#F7F5F0;--text:#1A2332;--muted:#6B7280;--line:#E4E0D8;--brand-ink:#0A0A0A;--brand-warn:#FFE500;--primary:#0F6B5C;--primary2:#0A5448;--primary-soft:#E6F4F0;--accent:#C45C26;--good:#168456;--bad:#c43f50;--warn:#a36a00;--code:#1A2332;--codeText:#e6e9f5;--radius-sm:10px;--radius:16px;--radius-lg:24px;--shadow-sm:0 1px 2px #1a233208,0 4px 12px #1a233208;--shadow:0 18px 55px #1a233212;--ease:cubic-bezier(.22,1,.36,1)}body.dark{--bg:#0E1412;--panel:#151C19;--panel2:#111714;--text:#EAF2EF;--muted:#9AADA6;--line:#2A3531;--primary:#3DB89A;--primary2:#5CC9AE;--primary-soft:#1A2E28;--accent:#E08A55;--code:#0A0E0C;--shadow-sm:0 1px 2px #0005;--shadow:0 18px 55px #0005}html{scroll-behavior:smooth}body{-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;letter-spacing:.005em}button,label.file,input,textarea{font:inherit}button,.secondary,.primary,.danger,label.file{min-height:42px;transition:background-color .18s ease,border-color .18s ease,color .18s ease,transform .18s var(--ease),box-shadow .18s ease}button:active,label.file:active{transform:translateY(1px)}button:focus-visible,label.file:focus-within,textarea:focus-visible,.tok:focus-visible{outline:3px solid color-mix(in srgb,var(--primary) 38%,transparent);outline-offset:2px}.icon-btn{min-width:42px;border-radius:10px}header{height:72px;padding:0 clamp(16px,3vw,34px);background:color-mix(in srgb,var(--panel) 88%,transparent);backdrop-filter:blur(16px);box-shadow:0 1px 0 var(--line);border:0}.brand{gap:12px}.brand b{font-size:22px;letter-spacing:-.04em}.brand span{padding-left:12px;border-left:1px solid var(--line)}.header-actions{gap:8px}.pill{font-weight:650;border:1px solid color-mix(in srgb,var(--good) 18%,transparent)}.layout{grid-template-columns:280px minmax(0,1fr);min-height:calc(100vh - 72px)}aside{top:72px;height:calc(100vh - 72px);padding:24px 18px;background:color-mix(in srgb,var(--panel) 94%,var(--bg));scrollbar-width:thin}.progress-box{padding:16px;border:1px solid var(--line);background:linear-gradient(145deg,var(--panel2),var(--panel));border-radius:var(--radius);box-shadow:var(--shadow-sm)}.progress-box b{font-size:13px}.progress-box #progressText{font-size:13px;font-weight:750;color:var(--primary);font-variant-numeric:tabular-nums}.bar{height:6px;margin:13px 0}.bar i{background:linear-gradient(90deg,var(--primary),var(--accent));box-shadow:0 0 12px color-mix(in srgb,var(--primary) 30%,transparent)}nav h4{font-size:11px;letter-spacing:.13em;text-transform:uppercase;margin:23px 11px 8px}nav button{position:relative;min-height:44px;padding:10px 11px;border-radius:11px;color:var(--muted);align-items:flex-start}nav button:hover{background:var(--panel2);color:var(--text)}nav button.active{background:var(--primary-soft);color:var(--primary);font-weight:700}nav button.active:before{content:"";position:absolute;left:-18px;top:10px;bottom:10px;width:3px;background:var(--primary);border-radius:0 4px 4px 0}.dot{flex:0 0 auto;width:10px;height:10px;margin-top:5px;background:var(--panel);border-color:color-mix(in srgb,var(--muted) 40%,transparent)}nav button.done .dot{border-color:var(--good);box-shadow:inset 0 0 0 2px var(--panel)}main{padding:0 clamp(22px,5vw,78px) 72px;max-width:1460px}.learning-trail{height:54px;display:flex;align-items:center;color:var(--muted);font-size:12px;border-bottom:1px solid var(--line);margin-bottom:48px}.learning-trail b{color:var(--text);font-weight:650}.learning-trail span{margin:0 8px;color:color-mix(in srgb,var(--muted) 50%,transparent)}.lesson-head,.practice-head{align-items:center;margin-bottom:42px}.lesson-copy{max-width:830px}.lesson-head h1,.practice-head h1{font-size:clamp(36px,4vw,58px);line-height:1.06;letter-spacing:-.045em;margin:15px 0 16px}.lesson-head p,.practice-head p{font-size:17px;line-height:1.75;margin:0}.tag{display:inline-flex;align-items:center;font-size:11px;letter-spacing:.08em;text-transform:uppercase;padding:7px 10px}.lesson-cta{display:flex;flex-wrap:wrap;align-items:center;justify-content:flex-end;gap:9px;min-width:260px}.reading-time{width:100%;text-align:right;color:var(--muted);font-size:12px}.primary,.secondary,.danger{padding:10px 16px;font-weight:650;border-radius:10px}.primary{box-shadow:0 7px 20px color-mix(in srgb,var(--primary) 22%,transparent)}.primary:hover{transform:translateY(-1px);box-shadow:0 10px 24px color-mix(in srgb,var(--primary) 28%,transparent)}.secondary:hover{border-color:color-mix(in srgb,var(--primary) 35%,var(--line));background:var(--panel2)}.danger{background:color-mix(in srgb,var(--bad) 12%,var(--panel));color:var(--bad);border:1px solid color-mix(in srgb,var(--bad) 22%,transparent)}article{max-width:920px;font-size:17px;line-height:1.9}article h2,section h2{font-size:25px;letter-spacing:-.025em;margin-top:43px;margin-bottom:13px}article p{color:color-mix(in srgb,var(--text) 86%,var(--muted));max-width:78ch}article code{font-family:ui-monospace,SFMono-Regular,Consolas,monospace;font-size:.88em;background:var(--primary-soft);color:var(--primary);border:1px solid color-mix(in srgb,var(--primary) 12%,transparent)}article .callout{margin:25px 0;padding:18px 20px;border:1px solid color-mix(in srgb,var(--primary) 16%,var(--line));border-left:4px solid var(--primary);background:linear-gradient(115deg,var(--primary-soft),var(--panel));border-radius:4px var(--radius) var(--radius) 4px}.syntax-lab{margin-top:48px;padding:28px;border:1px solid var(--line);border-radius:var(--radius-lg);background:var(--panel);box-shadow:var(--shadow-sm);max-width:1040px}.syntax-lab h2{margin-top:5px}.section-kicker{font-size:10px;font-weight:800;letter-spacing:.16em;color:var(--primary)}.token-code{margin:19px 0 14px;padding:24px;border-radius:14px;box-shadow:inset 0 0 0 1px #ffffff0d;font-size:15px}.tok{transition:background .15s ease,box-shadow .15s ease}.tok:hover{outline:0;background:#ffffff15;box-shadow:0 0 0 2px #ffffff20}.explain-card{border:0;background:var(--panel2);padding:18px 20px;line-height:1.65}.pager{max-width:1040px;padding-top:28px;border-top:1px solid var(--line);margin-top:42px}.practice-head{padding-bottom:28px;border-bottom:1px solid var(--line)}.exercise-actions{display:flex;align-items:center;gap:8px;flex-wrap:wrap;justify-content:flex-end}.autosave{width:100%;text-align:right;color:var(--muted);font-size:11px;opacity:.85}.autosave.saving{color:var(--warn)}.hint{padding:16px 18px;line-height:1.6;border-color:color-mix(in srgb,var(--warn) 22%,transparent);background:color-mix(in srgb,#f3b53f 10%,var(--panel));animation:reveal .22s var(--ease)}.workbench{grid-template-columns:minmax(0,1.05fr) minmax(0,.95fr);gap:18px}.editor-wrap,.result-wrap{min-height:520px;border-radius:var(--radius);box-shadow:var(--shadow-sm);transition:border-color .2s ease,box-shadow .2s ease}.editor-wrap:focus-within{border-color:color-mix(in srgb,var(--primary) 48%,var(--line));box-shadow:0 0 0 4px color-mix(in srgb,var(--primary) 8%,transparent),var(--shadow-sm)}.editor-top,.runbar,.tabs{height:48px;padding:0 15px;background:var(--panel2)}.editor-top>span:first-child{color:var(--text);font-weight:700}.editor-top>span:first-child:before{content:"";display:inline-block;width:7px;height:7px;background:var(--accent);border-radius:50%;margin-right:8px}textarea{height:420px;padding:22px;font-size:15px;line-height:1.72;caret-color:var(--primary)}.runbar{height:56px;background:var(--panel);gap:10px}.run-button{min-width:155px}.shortcut{margin-left:auto;color:var(--muted);font-size:11px}.tabs{height:49px;gap:4px}.tab{position:relative;padding:0 17px;font-weight:650}.tab.active{border:0}.tab.active:after{content:"";position:absolute;height:2px;left:12px;right:12px;bottom:0;background:var(--primary);border-radius:2px}.panel{height:469px;padding:22px;line-height:1.7}.diagnosis{padding:16px 17px;border:1px solid color-mix(in srgb,var(--bad) 18%,transparent);border-left:4px solid var(--bad);background:color-mix(in srgb,var(--bad) 7%,var(--panel));line-height:1.6}.practice-nav{align-items:center;padding-top:28px;border-top:1px solid var(--line)}.practice-nav span{font-size:12px;color:var(--muted);font-variant-numeric:tabular-nums}.toast{top:88px;right:25px;padding:12px 17px;border:1px solid #ffffff1c;box-shadow:0 16px 45px #0003;border-radius:11px}.mobile-overlay{display:none}
@keyframes reveal{from{opacity:0;transform:translateY(-4px)}to{opacity:1;transform:none}}
@media(max-width:1100px){.workbench{grid-template-columns:1fr}.editor-wrap,.result-wrap{min-height:480px}.panel{height:400px}.reading-time{display:none}.lesson-head,.practice-head{align-items:flex-start}.lesson-cta{min-width:auto}}
@media(max-width:900px){header{height:64px}.layout{min-height:calc(100vh - 64px)}aside{top:64px;height:calc(100vh - 64px);left:-300px;width:min(86vw,290px);z-index:40}.mobile-overlay{display:block;position:fixed;inset:64px 0 0;background:#080b1288;backdrop-filter:blur(2px);z-index:35;opacity:0;visibility:hidden;transition:.2s}.mobile-overlay.open{opacity:1;visibility:visible}main{padding:0 16px 56px}.learning-trail{margin-bottom:30px;height:48px}.lesson-head h1,.practice-head h1{font-size:37px}.lesson-head p,.practice-head p{font-size:16px}.lesson-head,.practice-head{margin-bottom:30px}.lesson-cta{justify-content:flex-start;margin-top:22px}.syntax-lab{padding:20px}.header-actions{gap:3px}.brand span{display:none}}
@media(max-width:560px){.lesson-head h1,.practice-head h1{font-size:33px}.syntax-lab{margin-inline:-4px;padding:17px}.workbench{margin-inline:-5px}.editor-top>span:last-child,.shortcut{display:none}.lesson-cta{display:grid;grid-template-columns:1fr 1fr;width:100%}.lesson-cta button{width:100%}.pager button{max-width:48%}.exercise-actions{justify-content:flex-start}.autosave{text-align:left}.practice-nav{gap:8px}.practice-nav span{display:none}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}}

/* v2.1.3 Ink Notebook polish */
.tag{background:var(--primary-soft);color:var(--primary)}
.lesson-head h1,.practice-head h1,.brand b{font-family:Fraunces,"Source Sans 3",serif}
.icon-btn{display:inline-flex;align-items:center;justify-content:center;padding:10px}
.icon-btn svg,.btn-icon{display:block;flex-shrink:0}
.run-button,.danger{display:inline-flex;align-items:center;justify-content:center;gap:8px}
.run-button:disabled,.primary:disabled{opacity:.48;cursor:not-allowed;transform:none;box-shadow:none}
.hint{border-color:color-mix(in srgb,var(--accent) 28%,transparent);background:color-mix(in srgb,var(--accent) 10%,var(--panel));color:var(--text)}
.ghost{border:1px dashed color-mix(in srgb,var(--bad) 35%,transparent);padding:12px;border-radius:10px}
.editor-wrap.passed{box-shadow:inset 3px 0 0 var(--good),var(--shadow-sm)}
.editor-wrap.mismatch{box-shadow:inset 3px 0 0 var(--warn,#a36a00),var(--shadow-sm)}
.pass-banner{display:flex;align-items:flex-start;gap:12px;padding:14px 16px;margin-bottom:14px;border-radius:12px;border:1px solid color-mix(in srgb,var(--good) 28%,transparent);background:color-mix(in srgb,var(--good) 10%,var(--panel));color:var(--text);animation:reveal .28s var(--ease)}
.next-step-bar{display:flex;align-items:center;gap:12px;flex-wrap:wrap;margin:0 0 14px;padding:10px 14px;border-radius:12px;border:1px solid color-mix(in srgb,var(--line, #ccc) 80%,transparent);background:color-mix(in srgb,var(--panel) 92%,var(--volt,#c8f000))}
.next-step-kicker{font-size:12px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.next-step-bar .primary{margin-left:auto}
.practice-align-note{margin:8px 0 0;font-size:13px;line-height:1.45;max-width:52rem}
.fail-rescue{margin:0 0 14px;padding:14px 16px;border-radius:12px;border:1px solid color-mix(in srgb,var(--warn,#a36a00) 40%,transparent);background:color-mix(in srgb,var(--warn,#a36a00) 10%,var(--panel))}
.fail-rescue b{display:block;color:var(--warn,#a36a00);margin-bottom:6px}
.fail-rescue-tips{margin:0 0 10px;padding-left:1.2em;color:var(--muted);font-size:13px;line-height:1.55}
.fail-rescue-actions{display:flex;flex-wrap:wrap;gap:8px}
.pass-banner b{color:var(--good)}
.pass-banner p{margin:4px 0 0;color:var(--muted);font-size:13px;line-height:1.5}
.mismatch-banner{display:flex;align-items:flex-start;gap:14px;padding:16px 18px;margin-bottom:16px;border-radius:12px;border:2px solid color-mix(in srgb,var(--warn,#a36a00) 55%,var(--bad));background:linear-gradient(135deg,color-mix(in srgb,var(--warn,#a36a00) 16%,var(--panel)),color-mix(in srgb,var(--bad) 8%,var(--panel)));color:var(--text);animation:mismatchPulse .9s var(--ease) 2;box-shadow:0 0 0 4px color-mix(in srgb,var(--warn,#a36a00) 18%,transparent)}
.mismatch-banner-icon{flex:0 0 auto;width:36px;height:36px;border-radius:50%;display:grid;place-items:center;font-weight:900;font-size:20px;line-height:1;color:#fff;background:var(--warn,#a36a00);box-shadow:0 4px 12px color-mix(in srgb,var(--warn,#a36a00) 35%,transparent)}
.mismatch-banner b{display:block;font-size:16px;line-height:1.35;color:var(--warn,#a36a00);letter-spacing:.01em}
.mismatch-banner p{margin:6px 0 0;color:var(--text);font-size:14px;line-height:1.55;font-weight:600}
.mismatch-tips{margin:10px 0 0;padding-left:1.15em;color:var(--muted);font-size:13px;line-height:1.55}
.mismatch-tips li{margin:4px 0}
.test-mismatch{padding:10px 12px;border-radius:10px;border:1px solid color-mix(in srgb,var(--bad) 28%,transparent);background:color-mix(in srgb,var(--bad) 7%,var(--panel))}
.test-mismatch .cmp-label{color:var(--muted);font-size:12px;font-weight:700}
.test-mismatch .cmp-expected,.test-mismatch .cmp-actual{display:inline-block;margin:2px 0 6px;padding:3px 8px;border-radius:6px;font:13px/1.5 ui-monospace,SFMono-Regular,Consolas,monospace;white-space:pre-wrap;word-break:break-word}
.test-mismatch .cmp-expected{background:color-mix(in srgb,var(--good) 12%,var(--panel));color:var(--good)}
.test-mismatch .cmp-actual{background:color-mix(in srgb,var(--bad) 12%,var(--panel));color:var(--bad)}
.diff-box{margin-top:12px;padding:12px 14px;border-radius:10px;border:1px dashed color-mix(in srgb,var(--warn,#a36a00) 45%,var(--line));background:color-mix(in srgb,var(--warn,#a36a00) 8%,var(--panel))}
.diff-title{font-size:13px;font-weight:800;color:var(--warn,#a36a00);margin:0 0 8px;letter-spacing:.02em}
.diff-list{margin:0;padding:0;list-style:none;display:grid;gap:8px}
.diff-list li{font-size:14px;line-height:1.55;font-weight:650;color:var(--text)}
.diff-pill{display:inline-block;min-width:2.6em;padding:2px 8px;margin-right:6px;border-radius:999px;font-size:12px;font-weight:800;letter-spacing:.04em;vertical-align:2px}
.diff-miss .diff-pill{background:color-mix(in srgb,var(--bad) 16%,var(--panel));color:var(--bad);border:1px solid color-mix(in srgb,var(--bad) 30%,transparent)}
.diff-extra .diff-pill{background:color-mix(in srgb,var(--warn,#a36a00) 18%,var(--panel));color:var(--warn,#a36a00);border:1px solid color-mix(in srgb,var(--warn,#a36a00) 35%,transparent)}
.diff-changed .diff-pill{background:color-mix(in srgb,var(--primary) 12%,var(--panel));color:var(--primary);border:1px solid color-mix(in srgb,var(--primary) 28%,transparent)}
.ws-dot{display:inline-block;padding:0 1px;color:var(--warn,#a36a00);font-weight:900;opacity:.85}
.diff-empty{color:var(--muted);font-style:italic;font-weight:600}
@keyframes mismatchPulse{0%,100%{transform:none;box-shadow:0 0 0 4px color-mix(in srgb,var(--warn,#a36a00) 18%,transparent)}45%{transform:translateY(-1px);box-shadow:0 0 0 7px color-mix(in srgb,var(--warn,#a36a00) 28%,transparent)}}
@media(prefers-reduced-motion:reduce){.mismatch-banner{animation:none}}
.empty-hint{color:var(--muted);font:inherit;line-height:1.65}
.panel.empty-hint{font-family:inherit}
#nextExerciseBtn.nudge{animation:nudge 1.1s var(--ease) 2}
@keyframes nudge{0%,100%{transform:none;box-shadow:0 7px 20px color-mix(in srgb,var(--primary) 22%,transparent)}40%{transform:translateY(-2px);box-shadow:0 12px 28px color-mix(in srgb,var(--primary) 34%,transparent)}}
.pill.err{background:color-mix(in srgb,var(--bad) 12%,transparent);color:var(--bad);border-color:color-mix(in srgb,var(--bad) 22%,transparent)}
@media(prefers-reduced-motion:reduce){#nextExerciseBtn.nudge{animation:none}}

/* v2.2.0 IA / logic polish */
.bridge-banner{position:fixed;inset:0 0 auto;z-index:200;padding:12px 18px;text-align:center;font-weight:700;font-size:13px;letter-spacing:.02em;background:#0A0A0A;color:#FFE500;border-bottom:4px solid #0A0A0A;transition:opacity .35s var(--ease),transform .35s var(--ease)}
.bridge-banner.hide{opacity:0;transform:translateY(-100%);pointer-events:none}
.home-link{text-decoration:none;display:inline-flex;align-items:center}
.progress-meta{display:flex;justify-content:space-between;gap:8px;margin:8px 0 4px}
.progress-meta small{color:var(--muted);font-variant-numeric:tabular-nums;font-weight:650}
.unit-group{border:1px solid var(--line);border-radius:12px;margin-bottom:10px;background:var(--panel);overflow:hidden}
.level-group{border:1px solid var(--line);border-radius:14px;margin-bottom:12px;background:var(--bg);overflow:hidden}
.level-group > summary{list-style:none;cursor:pointer;padding:12px 14px;display:flex;align-items:center;gap:10px;user-select:none;font-weight:750}
.level-group > summary::-webkit-details-marker{display:none}
.level-group > summary:after{content:"";margin-left:auto;width:7px;height:7px;border-right:2px solid var(--muted);border-bottom:2px solid var(--muted);transform:rotate(45deg);transition:transform .2s var(--ease)}
.level-group[open] > summary:after{transform:rotate(-135deg)}
.level-badge{display:inline-flex;align-items:center;padding:3px 10px;border-radius:999px;font-size:12px;letter-spacing:.06em;background:var(--primary-soft);color:var(--primary)}
.level-group[data-level="初級"] .level-badge{background:#e8f6ee;color:#1b7a45}
.level-group[data-level="中級"] .level-badge{background:#eef2ff;color:#3b4fd8}
.level-group[data-level="高級"] .level-badge{background:#fff1e8;color:#c24e0e}
.level-group[data-level="專業"] .level-badge{background:#f3e8ff;color:#7a3db8}
.level-count{font-size:12px;color:var(--muted);font-weight:600}
.level-group .unit-group{border:none;border-radius:0;margin:0;border-top:1px solid var(--line)}
.level-group .unit-group summary{padding-left:16px}
.dark .level-group[data-level="初級"] .level-badge{background:#163528;color:#6dcea0}
.dark .level-group[data-level="中級"] .level-badge{background:#1e2448;color:#9db0ff}
.dark .level-group[data-level="高級"] .level-badge{background:#3a2416;color:#ffb080}
.dark .level-group[data-level="專業"] .level-badge{background:#2a1a3d;color:#d4a8ff}
.unit-group summary{list-style:none;cursor:pointer;padding:11px 12px;font-size:12px;font-weight:750;letter-spacing:.04em;color:var(--muted);display:flex;align-items:center;justify-content:space-between;user-select:none}
.unit-group summary::-webkit-details-marker{display:none}
.unit-group summary:after{content:"";width:7px;height:7px;border-right:2px solid var(--muted);border-bottom:2px solid var(--muted);transform:rotate(45deg);transition:transform .2s var(--ease);margin-right:4px}
.unit-group[open] summary{color:var(--primary);background:var(--primary-soft)}
.unit-group[open] summary:after{transform:rotate(-135deg)}
.unit-group button{border-radius:0;width:100%}
nav button.read .dot{border-color:var(--accent);background:color-mix(in srgb,var(--accent) 35%,var(--panel))}
@media(max-width:900px){.home-link{display:none}}

.progress-hint{display:block;margin-top:6px;color:var(--muted);font-size:12px;line-height:1.4}
.progress-box .progress-hint{opacity:.9}

/* v2.3.2 search + sticky practice */
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);border:0}
.nav-search{display:block;margin:0 0 12px}
.nav-search input{width:100%;min-height:42px;padding:10px 12px;border:1px solid var(--line);border-radius:10px;background:var(--panel2);color:var(--text);outline:0}
.nav-search input:focus{border-color:color-mix(in srgb,var(--primary) 50%,var(--line));box-shadow:0 0 0 3px color-mix(in srgb,var(--primary) 12%,transparent)}
.search-empty{margin:0 0 12px;padding:10px 12px;border-radius:10px;background:var(--panel2);color:var(--muted);font-size:13px}
.nav-hidden{display:none!important}
.unit-group summary,.level-group > summary{gap:8px}
.unit-name{flex:1;min-width:0}
.unit-count,.level-count{font-variant-numeric:tabular-nums;font-size:11px;color:var(--primary);background:var(--primary-soft);padding:2px 7px;border-radius:99px}
.sticky-head{position:sticky;top:72px;z-index:12;background:color-mix(in srgb,var(--bg) 92%,transparent);backdrop-filter:blur(10px);padding-top:12px;margin-top:-12px;cursor:pointer}
.sticky-head .exercise-actions{cursor:default}
.result-wrap .tabs{position:sticky;top:0;z-index:2;backdrop-filter:blur(8px)}
.pass-banner{border-left:4px solid var(--good)}
.mismatch-banner{border-left:4px solid var(--warn,#a36a00)}
.practice-head h1{font-size:clamp(28px,3.4vw,42px)}
.practice-head p{display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden}
.practice-head.is-expanded p{-webkit-line-clamp:unset;overflow:visible}
@media(max-width:900px){.sticky-head{top:64px}}

.purpose-box{margin-top:12px;padding:12px 14px;border-radius:12px;border:1px solid var(--line);background:var(--primary-soft)}
.purpose-box b{display:block;font-size:12px;letter-spacing:.04em;color:var(--primary);margin-bottom:6px}
.purpose-box p{margin:0;line-height:1.55;color:var(--text)}
.quiz-flag{display:inline-block;margin-right:6px;padding:1px 6px;border-radius:6px;font-style:normal;font-size:11px;background:#fff1e8;color:#c24e0e}
.dark .quiz-flag{background:#3a2416;color:#ffb080}
#lessonNav button.locked{opacity:.55;cursor:not-allowed}
#lessonNav button.locked .dot{background:#999}

.demo-say{display:grid;gap:12px;margin:8px 0 4px}
.say-block{padding:12px 14px;border-radius:12px;border:1px solid var(--line);background:var(--panel)}
.say-block b{display:block;font-size:12px;letter-spacing:.04em;color:var(--primary);margin-bottom:6px}
.say-block p,.say-block li{margin:0;line-height:1.55;color:var(--text)}
.say-block ol{margin:0;padding-left:1.2em;display:grid;gap:6px}
.say-block li{font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;font-size:13px}

/* v2.3.3 first-run tour */
.tour{position:fixed;top:var(--header-h,84px);left:0;right:0;bottom:0;z-index:300;display:grid;place-items:center;padding:20px}
.tour.hidden{display:none!important}
.tour-backdrop{position:absolute;inset:0;background:#0a0a0acc;backdrop-filter:blur(2px)}
.tour-card{position:relative;z-index:1;width:min(520px,100%);background:var(--panel);border:1px solid var(--line);border-radius:16px;box-shadow:var(--shadow);padding:22px 22px 18px}
.tour-kicker{margin:0 0 8px;font-size:12px;font-weight:750;letter-spacing:.08em;color:var(--primary);text-transform:uppercase}
.tour-card h2{margin:0 0 10px;font-family:Fraunces,"Source Sans 3",serif;font-size:1.55rem;letter-spacing:-.03em;line-height:1.15}
.tour-card p#tourBody{margin:0 0 18px;color:var(--muted);line-height:1.65;white-space:pre-line;max-height:min(52vh,420px);overflow:auto}
.tour-actions{display:flex;justify-content:flex-end;gap:8px;flex-wrap:wrap}
body.tour-open #sidebar{outline:3px solid var(--primary);outline-offset:-3px}
body.tour-open.tour-spot-lesson #lessonPane{outline:3px solid var(--primary);outline-offset:4px;border-radius:12px}
body.tour-open.tour-spot-practice #practicePane{outline:3px solid var(--primary);outline-offset:4px;border-radius:12px}
body.tour-open.tour-spot-header .auth-chip{outline:3px solid var(--primary);outline-offset:4px;border-radius:12px}

/* v2.3.4 visual bridge landing ↔ classroom */
header{flex-wrap:wrap;align-content:center;padding-top:0}
.brand-rail{flex:0 0 100%;order:-1;height:5px;margin:0 -clamp(16px,3vw,34px) 0;width:calc(100% + 2*clamp(16px,3vw,34px));background:linear-gradient(90deg,var(--brand-ink,#0A0A0A) 0 42%,var(--brand-warn,#FFE500) 42% 58%,var(--primary) 58% 100%)}
.brand-badge{font-style:normal;font-size:10px;font-weight:800;letter-spacing:.08em;background:var(--brand-ink,#0A0A0A);color:var(--brand-warn,#FFE500);padding:3px 6px;border-radius:4px;margin-left:2px;vertical-align:middle}
.home-link{border:2px solid var(--brand-ink,#0A0A0A)!important;box-shadow:3px 3px 0 var(--brand-ink,#0A0A0A);font-weight:750}
.home-link:hover{transform:translate(-1px,-1px);box-shadow:4px 4px 0 var(--brand-ink,#0A0A0A)}
.bridge-banner{border-bottom:5px solid var(--brand-warn,#FFE500)!important}
@media(max-width:900px){.brand-rail{margin:0 -16px;width:calc(100% + 32px)}.brand-badge{display:none}}

.domain-group{border:1px solid var(--line);border-radius:12px;margin:8px 10px 10px;background:var(--panel);overflow:hidden}
.domain-group > summary{list-style:none;cursor:pointer;padding:10px 12px;display:flex;align-items:center;justify-content:space-between;gap:8px;user-select:none;font-weight:700}
.domain-group > summary::-webkit-details-marker{display:none}
.domain-badge{display:inline-flex;align-items:center;padding:2px 8px;border-radius:8px;font-size:12px;background:var(--primary-soft);color:var(--primary)}
.domain-group .unit-group{margin:8px}

/* v2.4.0 — Soft brand sync with Neo-Brutalist landing (option B)
   Same palette + type as landing.html; keep classroom radii & soft shadows. */
:root{
  --ink:#0A0A0A;
  --paper:#F4F0E6;
  --warn:#FFE500;
  --signal:#FF3B30;
  --volt:#00E5C0;
  --bg:var(--paper);
  --panel:#FFFdf8;
  --panel2:#F0EBE0;
  --text:var(--ink);
  --muted:#3A3A3A;
  --line:#D4CFC3;
  --brand-ink:var(--ink);
  --brand-warn:var(--warn);
  --primary:var(--ink);
  --primary2:#222;
  --primary-soft:#EDE8DC;
  --accent:var(--warn);
  --good:#0A8F6E;
  --bad:var(--signal);
  --warn-tone:#8A6A00;
  --code:var(--ink);
  --codeText:var(--volt);
  --shadow-sm:0 2px 0 #0A0A0A14,0 8px 24px #0A0A0A0F;
  --shadow:0 12px 36px #0A0A0A14;
  --ease:cubic-bezier(0.16,1,0.3,1)
}
body.dark{
  --bg:#0E0E0E;
  --panel:#161616;
  --panel2:#1C1C1C;
  --text:#F4F0E6;
  --muted:#A8A8A8;
  --line:#2E2E2E;
  --primary:var(--warn);
  --primary2:#fff06a;
  --primary-soft:#2A2610;
  --accent:var(--volt);
  --good:var(--volt);
  --bad:#FF6B63;
  --code:#050505;
  --codeText:var(--volt);
  --shadow-sm:0 2px 0 #0008,0 8px 24px #0006;
  --shadow:0 12px 36px #0008
}
html,body{font-family:"IBM Plex Sans",system-ui,sans-serif}
.lesson-head h1,.practice-head h1,.brand b,.tour-card h2{
  font-family:"Archivo Black","IBM Plex Sans",sans-serif;
  letter-spacing:-.03em
}
.brand b{color:var(--ink);font-size:1.25rem}
body.dark .brand b{color:var(--text)}
.brand-badge{
  background:var(--signal);color:#fff;
  border:2px solid var(--ink);border-radius:0;padding:.15rem .4rem;font-size:.65rem
}
.brand-rail{
  height:6px;
  background:linear-gradient(90deg,var(--ink) 0 40%,var(--warn) 40% 58%,var(--volt) 58% 100%)
}
.primary{
  background:var(--warn);color:var(--ink);
  border:2px solid var(--ink);
  box-shadow:4px 4px 0 var(--ink);
  border-radius:10px
}
.primary:hover{
  background:#fff06a;color:var(--ink);
  transform:translate(-1px,-1px);
  box-shadow:5px 5px 0 var(--ink)
}
.primary:disabled,.run-button:disabled{
  opacity:.45;transform:none;box-shadow:2px 2px 0 var(--line);cursor:not-allowed
}
.secondary,label.file{
  background:var(--panel);color:var(--text);
  border:2px solid var(--ink);border-radius:10px;
  box-shadow:3px 3px 0 #0A0A0A18
}
body.dark .secondary,body.dark label.file{border-color:var(--line);box-shadow:3px 3px 0 #0006}
.secondary:hover,label.file:hover{
  background:var(--panel2);
  transform:translate(-1px,-1px);
  box-shadow:4px 4px 0 #0A0A0A22
}
.danger:not(.ghost){
  background:var(--signal);color:#fff;
  border:2px solid var(--ink);border-radius:10px;
  box-shadow:3px 3px 0 var(--ink)
}
.ghost{
  border:2px dashed var(--signal);color:var(--signal);
  border-radius:10px;background:transparent
}
.icon-btn{
  border:2px solid var(--ink);border-radius:10px;
  background:var(--panel);box-shadow:2px 2px 0 #0A0A0A14
}
body.dark .icon-btn{border-color:var(--line)}
.tag{
  background:var(--warn);color:var(--ink);
  border:2px solid var(--ink);border-radius:6px;
  font-weight:700;letter-spacing:.06em
}
.pill{
  border:2px solid var(--ink);border-radius:999px;
  background:var(--volt);color:var(--ink);font-weight:700
}
.pill.wait{background:var(--warn);color:var(--ink)}
.pill.err{background:var(--signal);color:#fff;border-color:var(--ink)}
.progress-box{
  border:2px solid var(--ink);border-radius:12px;
  background:var(--panel);box-shadow:4px 4px 0 #0A0A0A14
}
.bar{background:var(--panel2);border:1px solid var(--line);border-radius:8px}
.bar i{background:linear-gradient(90deg,var(--volt),var(--warn));border-radius:6px;box-shadow:none}
.progress-box #progressText{color:var(--ink)}
body.dark .progress-box #progressText{color:var(--warn)}
.nav-search input{
  border:2px solid var(--ink);border-radius:10px;background:var(--panel)
}
body.dark .nav-search input{border-color:var(--line)}
.level-group,.unit-group,.domain-group{
  border:2px solid var(--ink);border-radius:12px;background:var(--panel)
}
body.dark .level-group,body.dark .unit-group,body.dark .domain-group{border-color:var(--line)}
.level-badge,.unit-count,.level-count,.domain-badge{
  background:var(--warn);color:var(--ink);
  border:1.5px solid var(--ink);border-radius:6px
}
.level-group[data-level="初級"] .level-badge,
.level-group[data-level="中級"] .level-badge,
.level-group[data-level="高級"] .level-badge,
.level-group[data-level="專業"] .level-badge{
  background:var(--warn);color:var(--ink)
}
.level-group[data-level="中級"] .level-badge{background:var(--volt)}
.level-group[data-level="高級"] .level-badge{background:#FFB020}
.level-group[data-level="專業"] .level-badge{background:var(--signal);color:#fff}
.unit-group[open] summary{color:var(--ink);background:color-mix(in srgb,var(--warn) 35%,var(--panel))}
nav button.active{background:color-mix(in srgb,var(--warn) 40%,var(--panel));color:var(--ink);font-weight:700}
nav button.active:before{background:var(--ink)}
body.dark nav button.active{background:var(--primary-soft);color:var(--warn)}
body.dark nav button.active:before{background:var(--warn)}
.syntax-lab,.purpose-box,.say-block,.explain-card{
  border:2px solid var(--ink);border-radius:12px;box-shadow:4px 4px 0 #0A0A0A10
}
body.dark .syntax-lab,body.dark .purpose-box,body.dark .say-block,body.dark .explain-card{border-color:var(--line)}
.section-kicker{color:var(--ink);background:var(--warn);display:inline-block;padding:.2rem .55rem;border:2px solid var(--ink);border-radius:4px}
body.dark .section-kicker{color:var(--ink)}
.token-code{border:3px solid var(--ink);border-radius:12px;box-shadow:6px 6px 0 var(--warn)}
.editor-wrap,.result-wrap{
  border:2px solid var(--ink);border-radius:12px;box-shadow:6px 6px 0 #0A0A0A14
}
body.dark .editor-wrap,body.dark .result-wrap{border-color:var(--line)}
.editor-wrap:focus-within{
  border-color:var(--ink);
  box-shadow:0 0 0 3px color-mix(in srgb,var(--volt) 45%,transparent),6px 6px 0 #0A0A0A14
}
.editor-wrap.passed{box-shadow:inset 4px 0 0 var(--volt),6px 6px 0 #0A0A0A14}
.editor-top>span:first-child:before{background:var(--warn);border-radius:0}
textarea{caret-color:var(--volt)}
.tab.active{color:var(--ink)}
.tab.active:after{background:var(--warn);height:3px}
body.dark .tab.active{color:var(--warn)}
.pass-banner{
  border:2px solid var(--ink);border-left:5px solid var(--volt);
  border-radius:12px;background:color-mix(in srgb,var(--volt) 18%,var(--panel));
  box-shadow:4px 4px 0 #0A0A0A14
}
.pass-banner b{color:var(--ink)}
body.dark .pass-banner b{color:var(--volt)}
.hint{
  border:2px solid var(--ink);border-radius:12px;
  background:color-mix(in srgb,var(--warn) 28%,var(--panel))
}
.home-link{
  border:2px solid var(--ink)!important;
  box-shadow:3px 3px 0 var(--ink);background:var(--panel)!important
}
.home-link:hover{background:var(--warn)!important}
.bridge-banner{border-bottom:5px solid var(--warn)!important}
.tour-card{
  border:3px solid var(--ink);border-radius:14px;
  box-shadow:10px 10px 0 var(--ink)
}
.tour-kicker{color:var(--ink);background:var(--warn);display:inline-block;padding:.25rem .55rem;border:2px solid var(--ink)}
.toast{
  background:var(--ink);color:var(--warn);
  border:3px solid var(--warn);border-radius:10px;box-shadow:6px 6px 0 var(--ink)
}
article .callout{
  border:2px solid var(--ink);border-left:5px solid var(--volt);
  background:color-mix(in srgb,var(--volt) 12%,var(--panel));border-radius:4px 12px 12px 4px
}
article code{
  background:var(--warn);color:var(--ink);
  border:1.5px solid var(--ink);border-radius:4px
}
.sticky-head{background:color-mix(in srgb,var(--paper) 94%,transparent)}
body.tour-open #sidebar,
body.tour-open.tour-spot-lesson #lessonPane,
body.tour-open.tour-spot-practice #practicePane{
  outline:3px solid var(--warn);outline-offset:2px
}
#nextExerciseBtn.nudge{
  animation:nudge-b 1.1s var(--ease) 2
}
@keyframes nudge-b{
  0%,100%{transform:none;box-shadow:4px 4px 0 var(--ink)}
  40%{transform:translate(-2px,-2px);box-shadow:7px 7px 0 var(--ink)}
}
@media(prefers-reduced-motion:reduce){#nextExerciseBtn.nudge{animation:none}}
/* Soft scrollbar nod to landing */
::-webkit-scrollbar{width:12px}
::-webkit-scrollbar-track{background:var(--panel2)}
::-webkit-scrollbar-thumb{background:var(--warn);border:2px solid var(--ink);border-radius:6px}
*{scrollbar-width:thin;scrollbar-color:var(--warn) var(--panel2)}
.autosave.saving{color:var(--warn-tone)}
.purpose-box b,.say-block b,.explain-card b{color:var(--ink)}
body.dark .purpose-box b,body.dark .say-block b,body.dark .explain-card b{color:var(--warn)}
.dark .level-group[data-level="初級"] .level-badge,
.dark .level-group[data-level="中級"] .level-badge,
.dark .level-group[data-level="高級"] .level-badge,
.dark .level-group[data-level="專業"] .level-badge{
  border-color:var(--text)
}
.dark .level-group[data-level="初級"] .level-badge{background:var(--volt);color:var(--ink)}
.dark .level-group[data-level="中級"] .level-badge{background:var(--warn);color:var(--ink)}
.dark .level-group[data-level="高級"] .level-badge{background:#FFB020;color:var(--ink)}
.dark .level-group[data-level="專業"] .level-badge{background:var(--signal);color:#fff}
.quiz-flag{background:var(--warn);color:var(--ink);border:1.5px solid var(--ink);border-radius:4px}
.dark .quiz-flag{background:var(--warn);color:var(--ink)}
header{border-bottom:2px solid var(--ink);background:color-mix(in srgb,var(--panel) 92%,transparent);backdrop-filter:blur(10px)}
body.dark header{border-bottom-color:var(--line)}
aside{border-right:2px solid var(--ink)}
body.dark aside{border-right-color:var(--line)}
button:focus-visible,label.file:focus-within,textarea:focus-visible,.tok:focus-visible,.nav-search input:focus{
  outline:3px solid color-mix(in srgb,var(--volt) 55%,transparent);outline-offset:2px
}

/* v2.5.123 — Full Neo-Brutalist classroom (option A)
   Match landing.html: 4–5px ink borders, hard 2D shadows, grain, near-zero radius. */
:root{
  --border:5px solid var(--ink);
  --border-sm:4px solid var(--ink);
  --hard-shadow:12px 12px 0 var(--ink);
  --hard-shadow-sm:6px 6px 0 var(--ink);
  --radius-sm:0;
  --radius:0;
  --radius-lg:0;
  --shadow-sm:var(--hard-shadow-sm);
  --shadow:var(--hard-shadow);
  --line:var(--ink);
  --panel:#FFFdf8;
  --panel2:#EDE8DC
}
body.dark{
  --border:5px solid var(--text);
  --border-sm:4px solid #F4F0E6;
  --hard-shadow:12px 12px 0 #F4F0E6;
  --hard-shadow-sm:6px 6px 0 #F4F0E6;
  --line:#F4F0E6;
  --shadow-sm:var(--hard-shadow-sm);
  --shadow:var(--hard-shadow)
}
body::before{
  content:"";
  position:fixed;inset:0;z-index:9998;
  pointer-events:none;opacity:.07;
  background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='220' height='220'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  mix-blend-mode:multiply
}
body.dark::before{opacity:.12;mix-blend-mode:soft-light}
.primary,.secondary,.danger,label.file,.icon-btn,.ghost,
.tag,.pill,.progress-box,.nav-search input,
.level-group,.unit-group,.domain-group,
.level-badge,.unit-count,.level-count,.domain-badge,
.syntax-lab,.purpose-box,.say-block,.explain-card,
.token-code,.editor-wrap,.result-wrap,.pass-banner,.hint,
.tour-card,.toast,article .callout,article code,.quiz-flag,
.section-kicker,.tour-kicker,.home-link,.brand-badge,
.search-empty,.diagnosis{
  border-radius:0!important
}
.primary{
  border:var(--border-sm);
  box-shadow:var(--hard-shadow-sm);
  backdrop-filter:contrast(120%);
  transition:transform .25s var(--ease),box-shadow .25s var(--ease),background .25s var(--ease)
}
.primary:hover{
  transform:translate(-3px,-3px);
  box-shadow:10px 10px 0 var(--ink)
}
.primary:active{transform:translate(2px,2px);box-shadow:2px 2px 0 var(--ink)}
.primary:disabled,.run-button:disabled{
  transform:none;box-shadow:4px 4px 0 var(--panel2);opacity:.5
}
.secondary,label.file,.icon-btn{
  border:var(--border-sm);
  box-shadow:var(--hard-shadow-sm);
  backdrop-filter:contrast(120%);
  transition:transform .25s var(--ease),box-shadow .25s var(--ease),background .25s var(--ease)
}
.secondary:hover,label.file:hover,.icon-btn:hover{
  transform:translate(-3px,-3px);
  box-shadow:10px 10px 0 var(--ink);
  background:var(--warn)
}
.danger:not(.ghost){
  border:var(--border-sm);box-shadow:var(--hard-shadow-sm)
}
.danger:not(.ghost):hover{transform:translate(-2px,-2px);box-shadow:8px 8px 0 var(--ink)}
.ghost{border:3px dashed var(--signal);box-shadow:none}
.tag,.section-kicker,.tour-kicker,.quiz-flag,.brand-badge{
  border:3px solid var(--ink)
}
.pill{border:3px solid var(--ink);border-radius:0!important}
.progress-box{
  border:var(--border);box-shadow:var(--hard-shadow-sm)
}
.bar{border:3px solid var(--ink);border-radius:0;background:var(--panel2);height:10px}
.bar i{border-radius:0}
.nav-search input{border:var(--border-sm);box-shadow:3px 3px 0 var(--ink)}
.level-group,.unit-group,.domain-group{
  border:var(--border-sm);box-shadow:4px 4px 0 var(--ink);overflow:hidden
}
.level-badge,.unit-count,.level-count,.domain-badge{border:2px solid var(--ink)}
.syntax-lab,.purpose-box,.say-block,.explain-card,.hint,.pass-banner,.diagnosis{
  border:var(--border-sm);box-shadow:var(--hard-shadow-sm)
}
.pass-banner{border-left:8px solid var(--volt)}
.token-code{
  border:var(--border);box-shadow:8px 8px 0 var(--warn)
}
.editor-wrap,.result-wrap{
  border:var(--border);box-shadow:var(--hard-shadow)
}
.editor-wrap:focus-within{
  box-shadow:var(--hard-shadow),0 0 0 4px var(--volt)
}
.editor-wrap.passed{
  box-shadow:inset 6px 0 0 var(--volt),var(--hard-shadow)
}
.home-link{
  border:var(--border-sm)!important;
  box-shadow:var(--hard-shadow-sm)!important
}
.home-link:hover{
  transform:translate(-3px,-3px);
  box-shadow:10px 10px 0 var(--ink)!important;
  background:var(--warn)!important
}
.tour-card{
  border:var(--border);box-shadow:var(--hard-shadow)
}
.toast{
  border:var(--border-sm);box-shadow:var(--hard-shadow-sm);border-radius:0!important
}
article .callout{
  border:var(--border-sm);border-left:8px solid var(--volt);box-shadow:4px 4px 0 var(--ink)
}
article code{border:2px solid var(--ink)}
header{
  border-bottom:var(--border);
  background:color-mix(in srgb,var(--paper) 88%,transparent);
  backdrop-filter:contrast(118%) saturate(110%);
  box-shadow:none
}
aside{border-right:var(--border)}
.brand-rail{height:8px;border-bottom:3px solid var(--ink)}
.brand b{
  font-size:1.35rem;letter-spacing:-.03em
}
.lesson-head h1,.practice-head h1{
  line-height:.92;letter-spacing:-.04em
}
.dot{border-radius:0;border:2px solid var(--ink);width:10px;height:10px}
nav button.done .dot{background:var(--volt);border-color:var(--ink);box-shadow:none}
nav button.read .dot{background:var(--warn);border-color:var(--ink)}
nav button.active:before{width:5px;border-radius:0;background:var(--warn)}
body.dark nav button.active:before{background:var(--warn)}
.learning-trail{border-bottom:3px solid var(--ink);font-weight:600}
.pager,.practice-nav,.practice-head{border-color:var(--ink)}
.editor-top,.runbar,.tabs{
  border-color:var(--ink)!important;
  background:var(--panel2);font-weight:600
}
.tab.active:after{height:4px;background:var(--warn);border-radius:0;left:0;right:0}
.search-empty{border:3px solid var(--ink);box-shadow:3px 3px 0 var(--ink);background:var(--warn)}
#nextExerciseBtn.nudge{animation:nudge-a 1.1s var(--ease) 2}
@keyframes nudge-a{
  0%,100%{transform:none;box-shadow:var(--hard-shadow-sm)}
  40%{transform:translate(-4px,-4px);box-shadow:12px 12px 0 var(--ink)}
}
@media(prefers-reduced-motion:reduce){#nextExerciseBtn.nudge{animation:none}}
/* Landing-identical scrollbar */
::-webkit-scrollbar{width:14px}
::-webkit-scrollbar-track{background:var(--ink);border-radius:0}
::-webkit-scrollbar-thumb{background:var(--warn);border:3px solid var(--ink);border-radius:0}
::-webkit-scrollbar-thumb:hover{background:#fff06a}
*{scrollbar-width:thick;scrollbar-color:var(--warn) var(--ink)}
body.tour-open #sidebar,
body.tour-open.tour-spot-lesson #lessonPane,
body.tour-open.tour-spot-practice #practicePane{
  outline:4px solid var(--warn);outline-offset:0
}
.mobile-overlay{background:#0A0A0Acc;backdrop-filter:contrast(120%)}
@media(max-width:900px){
  .primary:hover,.secondary:hover,label.file:hover,.icon-btn:hover,.home-link:hover{
    transform:none;box-shadow:var(--hard-shadow-sm)
  }
}

/* v2.5.123 — logo / chrome parity with landing */
.brand .logo{
  font-family:"Archivo Black","IBM Plex Sans",sans-serif;
  font-size:1.35rem;letter-spacing:-.03em;
  color:var(--ink);text-decoration:none;
  display:inline-flex;align-items:baseline;gap:.45rem
}
body.dark .brand .logo{color:var(--text)}
.brand .logo i{
  font-style:normal;font-size:.65rem;letter-spacing:.08em;
  background:var(--signal);color:#fff;
  padding:.2rem .4rem;border:3px solid var(--ink)
}
.brand span{
  font-size:13px;font-weight:600;color:var(--muted);
  padding-left:12px;border-left:3px solid var(--ink)
}
body.dark .brand span{border-left-color:var(--line)}
.bridge-banner{
  font-family:"IBM Plex Sans",system-ui,sans-serif;
  letter-spacing:.04em;text-transform:uppercase;font-size:12px
}
.tour-card .tour-kicker,
.section-kicker{
  font-family:"IBM Plex Sans",system-ui,sans-serif;
  text-transform:uppercase;letter-spacing:.14em;font-weight:700
}
.learning-trail{
  font-family:"IBM Plex Sans",system-ui,sans-serif;
  text-transform:uppercase;letter-spacing:.06em;font-size:11px
}
#engine.pill{text-transform:uppercase;letter-spacing:.06em;font-size:11px}
.editor-top>span:first-child{
  font-family:"Archivo Black","IBM Plex Sans",sans-serif;
  letter-spacing:.02em;text-transform:uppercase;font-size:12px
}

/* v2.5.123 — Reading comfort (pack 1) under Brutalist chrome */
#lessonPane{
  max-width:52rem
}
#lessonPane .lesson-copy{
  max-width:40rem
}
#lessonPane h1{
  line-height:1.05;
  margin:14px 0 18px;
  max-width:18ch
}
#lessonPane #lessonIntro{
  font-size:clamp(1.05rem,1.6vw,1.2rem);
  line-height:1.7;
  color:var(--muted);
  max-width:36ch
}
#lessonBody{
  font-size:clamp(1.05rem,1.35vw,1.125rem);
  line-height:1.85;
  letter-spacing:.01em;
  max-width:40rem
}
#lessonBody h2{
  font-family:"Archivo Black","IBM Plex Sans",sans-serif;
  font-size:clamp(1.35rem,2.2vw,1.65rem);
  line-height:1.2;
  letter-spacing:-.03em;
  margin:2.4rem 0 .85rem;
  padding-bottom:.45rem;
  border-bottom:4px solid var(--ink)
}
body.dark #lessonBody h2{border-bottom-color:var(--line)}
#lessonBody p{
  margin:0 0 1.15em;
  color:color-mix(in srgb,var(--text) 92%,var(--muted));
  max-width:62ch
}
#lessonBody ul,#lessonBody ol{
  margin:0 0 1.2em;
  padding-left:1.35em;
  max-width:62ch;
  display:grid;gap:.55em
}
#lessonBody li{line-height:1.75}
#lessonBody code{
  font-size:.9em;
  padding:.12em .4em;
  box-decoration-break:clone;
  -webkit-box-decoration-break:clone
}
#lessonBody .callout{
  margin:1.6rem 0;
  padding:1.15rem 1.25rem;
  line-height:1.7;
  background:color-mix(in srgb,var(--volt) 14%,var(--panel));
  max-width:40rem
}
#lessonBody .callout strong,
#lessonBody .callout b{font-weight:700}
.purpose-box{
  margin-top:1rem;
  padding:1rem 1.15rem;
  max-width:40rem;
  line-height:1.65
}
.purpose-box b{
  font-size:11px;letter-spacing:.12em;text-transform:uppercase;
  background:var(--warn);color:var(--ink);
  display:inline-block;padding:.2rem .5rem;border:2px solid var(--ink);
  margin-bottom:.65rem
}
.syntax-lab{
  margin-top:2.5rem;
  padding:clamp(1.25rem,3vw,1.85rem);
  max-width:48rem;
  background:var(--panel)
}
.syntax-lab h2{
  font-family:"Archivo Black","IBM Plex Sans",sans-serif;
  font-size:clamp(1.25rem,2vw,1.5rem);
  line-height:1.2;
  margin:.55rem 0 .75rem
}
.syntax-lab>.muted{
  font-size:1rem;line-height:1.65;max-width:42ch;margin:0 0 1rem
}
.syntax-lab .token-code{
  font-size:clamp(.95rem,1.2vw,1.05rem);
  line-height:1.9;
  padding:1.25rem 1.35rem;
  margin:1rem 0
}
.syntax-lab .explain-card{
  padding:1.1rem 1.25rem;
  font-size:1.02rem;
  line-height:1.7;
  min-height:5.5rem;
  background:color-mix(in srgb,var(--warn) 12%,var(--panel))
}
.demo-say{gap:14px;margin:12px 0 8px;max-width:48rem}
.demo-translation{margin:8px 0 12px;padding:14px 16px;border-radius:12px;border:2px solid var(--line);background:color-mix(in srgb,var(--primary-soft) 60%,var(--panel));font-size:.92rem;line-height:1.7}
.demo-translation .tl-summary{margin:0 0 14px;padding:12px 14px;border:2px solid var(--line);border-radius:10px;background:color-mix(in srgb,var(--panel) 88%,var(--primary-soft))}
.demo-translation .tl-para{margin:0;color:var(--text);font-size:.98rem;line-height:1.75;white-space:pre-wrap}
.demo-translation .tl-line{display:grid;grid-template-columns:minmax(8rem,auto) 1fr;gap:10px;padding:4px 0;border-bottom:1px solid var(--line);align-items:start}
.demo-translation .tl-line:last-child{border-bottom:none}
.demo-translation .tl-code{font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;font-size:.88rem;color:var(--code);white-space:pre-wrap;background:var(--panel);padding:2px 6px;border-radius:4px}
.demo-translation .tl-text{color:var(--text);padding:2px 0}
.demo-translation .tl-title{font-weight:700;font-size:.82rem;letter-spacing:.06em;color:var(--primary);margin-bottom:8px}
#translateDemoBtn.active{background:var(--primary);color:#fff}
.say-block{
  padding:1rem 1.15rem;line-height:1.65
}
.say-block b{
  font-size:11px;letter-spacing:.12em;text-transform:uppercase;
  background:var(--volt);color:var(--ink);
  display:inline-block;padding:.2rem .5rem;border:2px solid var(--ink);
  margin-bottom:.55rem
}
.say-block p{font-size:1.02rem;max-width:48ch}
.say-block li{font-size:.95rem;line-height:1.6}
.learning-trail{
  margin-bottom:2rem;
  letter-spacing:.08em
}
.pager{
  margin-top:2.5rem;
  padding-top:1.5rem;
  border-top:4px solid var(--ink);
  max-width:48rem
}
body.dark .pager{border-top-color:var(--line)}
@media(max-width:900px){
  #lessonPane{max-width:none}
  #lessonBody,#lessonBody .callout,.purpose-box,.syntax-lab{max-width:none}
  #lessonBody{font-size:1.05rem;line-height:1.8}
  #lessonPane h1{max-width:none}
}

.swap-bar{display:flex;align-items:center;gap:10px;margin:10px 0 12px;flex-wrap:wrap}
.swap-label{font-size:13px}
#swapDemoBtn,#swapExerciseBtn,#prevExerciseBtn{min-height:38px}

/* v2.5.123 — P0–P2 UX fixes from audit */
.skip-link{
  position:absolute;left:12px;top:-64px;z-index:10000;
  background:var(--warn);color:var(--ink);
  border:4px solid var(--ink);box-shadow:6px 6px 0 var(--ink);
  padding:.7rem 1rem;font-weight:700;text-decoration:none
}
.skip-link:focus{top:12px}
.xfer-wrap{position:relative;display:inline-flex;align-items:center;gap:8px}
.more-btn{display:none}
.more-panel{display:flex;align-items:center;gap:8px}
.more-item{white-space:nowrap}
@media(max-width:900px){
  .home-link{display:inline-flex!important;padding:8px 10px;font-size:12px;min-height:42px}
  .more-btn{display:inline-flex}
  .more-panel{
    position:absolute;right:0;top:calc(100% + 8px);z-index:50;
    flex-direction:column;align-items:stretch;gap:0;
    min-width:180px;padding:0;
    background:var(--panel);border:4px solid var(--ink);
    box-shadow:8px 8px 0 var(--ink)
  }
  .more-panel[hidden]{display:none!important}
  .more-panel .more-item{
    width:100%;border:0!important;border-radius:0!important;
    box-shadow:none!important;justify-content:flex-start;
    border-bottom:3px solid var(--ink)!important
  }
  .more-panel .more-item:last-child{border-bottom:0!important}
  .header-actions > .secondary:not(.home-link):not(.more-item){display:none}
}
@media(min-width:901px){
  .more-btn{display:none!important}
  .more-panel[hidden]{display:flex!important}
}
.runbar .primary,.runbar .danger{min-height:52px;padding:.75rem 1.2rem;font-weight:700}
.run-button{min-width:168px}
.result-wrap{scroll-margin-top:88px}
.toast{
  cursor:pointer;max-width:min(420px,calc(100vw - 32px));
  line-height:1.45
}
.toast.show{pointer-events:auto}
.nav-search{margin-bottom:14px}
.nav-search input{
  min-height:46px;font-weight:600;
  border:4px solid var(--ink)!important;
  box-shadow:4px 4px 0 var(--ink)
}
.nav-search input::placeholder{color:var(--muted);font-weight:500}
.progress-box{margin-bottom:14px}
@media(max-width:560px){
  .brand .logo{font-size:1.05rem}
  .brand .logo i{font-size:.55rem;padding:.15rem .3rem}
  .home-link{padding:6px 8px}
  #engine.pill{font-size:10px;padding:4px 7px}
}

/* v2.5.123 — Typography: tracking, leading, rhythm */
:root{
  --tracking-tight:-.02em;
  --tracking-display:-.02em;
  --tracking-logo:-.02em;
  --tracking-body:.02em;
  --tracking-ui:.04em;
  --tracking-eyebrow:.12em;
  --leading-display:1.12;
  --leading-body:1.8;
  --leading-ui:1.45;
  --space-1:.5rem;
  --space-2:.75rem;
  --space-3:1.25rem;
  --space-4:2rem;
  --space-5:2.75rem
}
html,body{
  letter-spacing:var(--tracking-body);
  line-height:var(--leading-body);
  word-break:normal;
  overflow-wrap:anywhere;
  text-spacing-trim:space-all
}
.brand .logo,
.lesson-head h1,.practice-head h1,
#lessonBody h2,.syntax-lab h2,.tour-card h2{
  letter-spacing:var(--tracking-display);
  line-height:var(--leading-display);
  text-wrap:balance
}
.brand .logo i,
.section-kicker,.tour-kicker,.learning-trail,
.tag,.pill,#engine.pill,.purpose-box b,.say-block b,
.level-badge,.unit-count,.level-count,.domain-badge{
  letter-spacing:var(--tracking-ui);
  line-height:var(--leading-ui)
}
.brand span,
.header-actions button,.header-actions a,.header-actions label,
.lesson-cta button,.exercise-actions button,.pager button,.practice-nav button,
.nav-search input,nav button,aside .progress-box,
.muted,.autosave,.progress-hint,.progress-meta small{
  letter-spacing:var(--tracking-ui);
  line-height:var(--leading-ui)
}
#lessonPane h1{
  line-height:1.1;
  letter-spacing:var(--tracking-display);
  margin:var(--space-2) 0 var(--space-3);
  max-width:14em
}
#lessonPane #lessonIntro{
  letter-spacing:var(--tracking-body);
  line-height:1.7;
  margin:0 0 var(--space-3)
}
#lessonBody{
  letter-spacing:.018em;
  line-height:1.88
}
#lessonBody h2{
  margin:var(--space-5) 0 var(--space-2);
  padding-bottom:var(--space-1);
  line-height:1.25
}
#lessonBody p{
  margin:0 0 1.1em;
  letter-spacing:.018em;
  line-height:1.88
}
#lessonBody li{
  letter-spacing:.015em;
  line-height:1.8;
  margin:0
}
#lessonBody .callout{
  letter-spacing:.015em;
  line-height:1.75;
  margin:var(--space-4) 0
}
.syntax-lab{
  margin-top:var(--space-5);
  padding:var(--space-3) clamp(1rem,3vw,1.75rem)
}
.syntax-lab h2{margin:var(--space-1) 0 var(--space-2);line-height:1.25}
.syntax-lab>.muted{letter-spacing:.02em;line-height:1.65;margin:0 0 var(--space-3)}
.syntax-lab .token-code{
  letter-spacing:.01em;
  line-height:1.95;
  margin:var(--space-2) 0 var(--space-3)
}
.syntax-lab .explain-card{
  letter-spacing:.02em;
  line-height:1.7;
  padding:var(--space-3)
}
.say-block,.purpose-box{
  letter-spacing:.018em;
  line-height:1.7;
  padding:var(--space-3)
}
.say-block p,.purpose-box p{letter-spacing:.018em;line-height:1.75;margin:0}
.practice-head h1{
  letter-spacing:var(--tracking-display);
  line-height:1.12;
  margin:var(--space-2) 0 var(--space-2)
}
.practice-head p{
  letter-spacing:.02em;
  line-height:1.7
}
.lesson-head,.practice-head{
  gap:var(--space-3);
  margin-bottom:var(--space-4)
}
.learning-trail{
  letter-spacing:.1em;
  margin-bottom:var(--space-4);
  line-height:1.4
}
.progress-box{
  letter-spacing:.03em;
  line-height:1.45
}
.progress-box b{letter-spacing:.06em}
nav button{
  letter-spacing:.03em;
  line-height:1.4;
  padding:11px 12px;
  gap:10px
}
nav button span{letter-spacing:.025em}
.unit-group summary,.level-group>summary,.domain-group>summary{
  letter-spacing:.06em;
  line-height:1.35
}
.toast{
  letter-spacing:.03em;
  line-height:1.5;
  padding:14px 18px
}
.bridge-banner{
  letter-spacing:.08em;
  line-height:1.4;
  word-spacing:.05em
}
.primary,.secondary,.danger,label.file{
  letter-spacing:.04em;
  line-height:1.3
}
.editor-top,.runbar,.tabs{
  letter-spacing:.05em;
  line-height:1.3
}
textarea,#outputPanel,#testsPanel pre,.token-code,.panel{
  letter-spacing:0;
  line-height:1.7
}
.pass-banner{
  letter-spacing:.02em;
  line-height:1.55;
  gap:var(--space-2);
  padding:var(--space-3)
}
.pass-banner p{letter-spacing:.02em;line-height:1.6;margin:6px 0 0}
.hint{
  letter-spacing:.02em;
  line-height:1.65;
  padding:var(--space-3)
}
.pager,.practice-nav{
  margin-top:var(--space-4);
  padding-top:var(--space-3);
  gap:var(--space-2)
}
.workbench{gap:var(--space-3)}
@media(max-width:900px){
  body{letter-spacing:.015em}
  #lessonBody{line-height:1.82;letter-spacing:.015em}
  .lesson-head h1,.practice-head h1{line-height:1.15;letter-spacing:-.025em}
  .learning-trail{margin-bottom:var(--space-3)}
}

/* v2.5.123 — Practice desk + visual breathing room */
.sticky-head{
  top:76px;
  padding:var(--space-2) 0 var(--space-3);
  margin:0 0 var(--space-3);
  border-bottom:4px solid var(--ink);
  background:color-mix(in srgb,var(--paper) 94%,transparent)
}
body.dark .sticky-head{
  border-bottom-color:var(--line);
  background:color-mix(in srgb,var(--bg) 94%,transparent)
}
.sticky-head .tag{margin-bottom:2px}
.exercise-actions{
  gap:var(--space-1);
  margin-top:var(--space-2)
}
.exercise-actions .secondary{
  min-height:44px;
  padding:8px 12px;
  letter-spacing:.03em
}
.autosave{
  opacity:.9;
  margin-bottom:4px;
  font-variant-numeric:tabular-nums
}
.workbench{
  gap:var(--space-4);
  align-items:start
}
.editor-wrap,.result-wrap{
  min-height:540px
}
.editor-top,.tabs{
  min-height:48px;
  padding:0 var(--space-3)
}
.runbar{
  min-height:60px;
  padding:8px var(--space-3);
  gap:12px;
  flex-wrap:wrap
}
.panel,.panel.empty-hint{
  padding:var(--space-3) clamp(1rem,2.5vw,1.35rem);
  letter-spacing:.02em;
  line-height:1.7
}
.panel.empty-hint{
  color:var(--muted);
  background:
    repeating-linear-gradient(-45deg,transparent,transparent 10px,color-mix(in srgb,var(--ink) 4%,transparent) 10px,color-mix(in srgb,var(--ink) 4%,transparent) 12px),
    var(--panel2);
  border-top:3px solid var(--ink);
  display:grid;
  place-content:center;
  text-align:center;
  max-width:none
}
body.dark .panel.empty-hint{
  background:
    repeating-linear-gradient(-45deg,transparent,transparent 10px,color-mix(in srgb,var(--text) 6%,transparent) 10px,color-mix(in srgb,var(--text) 6%,transparent) 12px),
    var(--panel2)
}
.pass-banner{
  margin-bottom:var(--space-3)
}
.hint{
  margin-bottom:var(--space-3)
}
/* Secondary chrome: slightly lighter borders so primary CTA frames win */
.unit-group,.domain-group,.level-group{
  border-width:3px!important;
  box-shadow:3px 3px 0 var(--ink)
}
.explain-card,.purpose-box,.say-block{
  border-width:3px!important;
  box-shadow:3px 3px 0 var(--ink)
}
.syntax-lab,.editor-wrap,.result-wrap,.progress-box,.token-code{
  border-width:4px!important
}
aside{
  padding:var(--space-3) var(--space-2)
}
.progress-box{padding:var(--space-3)}
.nav-search{margin:0 0 var(--space-3)}
#lessonNav{display:grid;gap:2px}
.practice-nav{
  gap:var(--space-2);
  align-items:center
}
.practice-nav .primary{min-height:52px}
.tab{
  letter-spacing:.06em;
  padding:0 18px
}
.tab.active:after{height:5px}
@media(max-width:1100px){
  .workbench{gap:var(--space-3)}
  .editor-wrap,.result-wrap{min-height:480px}
  .sticky-head{top:68px}
}
@media(max-width:900px){
  .sticky-head{top:64px;padding-bottom:var(--space-2)}
  .runbar{min-height:56px}
  .exercise-actions{width:100%}
}

/* v2.5.123 — Fix logo occlusion + refine tracking */
:root{--header-h:84px}
header{
  height:auto!important;
  min-height:var(--header-h);
  overflow:visible!important;
  flex-wrap:nowrap!important;
  align-items:center;
  gap:10px;
  z-index:210;
  padding:0 clamp(12px,2.5vw,28px) 0;
  padding-top:0
}
.brand-rail{
  position:absolute;
  left:0;right:0;top:0;
  width:100%!important;
  margin:0!important;
  height:6px;
  border-bottom:3px solid var(--ink);
  order:0;
  flex:none
}
header > :not(.brand-rail){position:relative;z-index:1}
header{
  position:sticky;
  padding-top:9px!important
}
.brand{
  flex:1 1 auto;
  min-width:0;
  overflow:visible;
  align-items:center;
  gap:10px
}
.brand .logo{
  flex:0 0 auto;
  white-space:nowrap;
  overflow:visible;
  letter-spacing:-.02em!important;
  line-height:1.15!important;
  font-size:clamp(1.15rem,2.8vw,1.4rem)!important;
  padding:2px 0;
  display:inline-flex;
  align-items:center;
  gap:.4rem
}
.brand .logo i{
  letter-spacing:.1em!important;
  line-height:1!important;
  flex:0 0 auto;
  transform:translateY(-1px)
}
.brand span{
  white-space:nowrap;
  overflow:hidden;
  text-overflow:ellipsis;
  letter-spacing:.04em!important;
  line-height:1.3!important;
  min-width:0
}
#menuBtn{flex:0 0 auto}
.header-actions{
  flex:0 1 auto;
  flex-wrap:nowrap;
  min-width:0;
  gap:8px
}
/* Bridge below header so it never covers PyTutor */
.bridge-banner{
  top:var(--header-h)!important;
  z-index:200;
  letter-spacing:.06em!important;
  line-height:1.45!important
}
body.bridge-on{padding-top:0}
.layout{min-height:calc(100vh - var(--header-h))}
aside{top:var(--header-h);height:calc(100vh - var(--header-h))}
.sticky-head{top:var(--header-h)}
@media(max-width:900px){
  :root{--header-h:76px}
  .mobile-overlay{inset:var(--header-h) 0 0}
  aside{top:var(--header-h);height:calc(100vh - var(--header-h))}
  .brand span{display:none}
  .brand .logo{font-size:1.2rem!important;letter-spacing:-.015em!important}
  .home-link{letter-spacing:.03em!important}
}
/* Global tracking polish: shared with landing */
.lesson-head h1,.practice-head h1,.tour-card h2{
  letter-spacing:var(--tracking-display)!important;
  line-height:var(--leading-display)!important
}
#lessonBody,#lessonBody p{
  letter-spacing:var(--tracking-body)!important;
  line-height:1.88!important
}
#lessonBody h2{
  letter-spacing:var(--tracking-display)!important;
  line-height:1.28!important
}
.brand .logo{
  letter-spacing:var(--tracking-logo)!important
}
nav button span{
  letter-spacing:.02em!important;
  line-height:1.4!important
}

.legal-strip{margin:0;padding:10px 18px 18px;font-size:12px;color:var(--muted);text-align:center;border-top:2px solid var(--ink, #0A0A0A)}
.legal-strip a{color:inherit;font-weight:700;text-underline-offset:2px}
body.dark .legal-strip{border-top-color:var(--line)}


/* v2.5.123 — auth + certificate (legacy layout; menu chrome in v2.5.123) */
.auth-chip{display:flex;align-items:center;gap:6px;flex-wrap:wrap;max-width:min(420px,48vw)}
.auth-user{font-size:12px;font-weight:700;color:var(--muted);white-space:nowrap;max-width:9em;overflow:hidden;text-overflow:ellipsis}
.auth-btn{padding:6px 10px!important;font-size:12px!important;min-height:34px}
.cert-badge{display:inline-grid;place-items:center;width:22px;height:22px;border-radius:4px;background:#FFE500;color:#0A0A0A;font-weight:900;font-size:12px;border:2px solid #0A0A0A}
.pt-modal{position:fixed;inset:0;z-index:400;display:grid;place-items:center;padding:20px}
.pt-modal.hidden{display:none!important}
.pt-modal-backdrop{position:absolute;inset:0;background:#0a0a0acc;backdrop-filter:blur(2px)}
.pt-modal-card{position:relative;z-index:1;width:min(440px,100%);background:var(--panel);border:2px solid var(--brand-ink,#0A0A0A);box-shadow:6px 6px 0 var(--brand-ink,#0A0A0A);padding:22px;border-radius:4px}
.pt-modal-card h2{margin:0 0 8px;font-family:"Archivo Black",sans-serif;font-size:1.35rem;letter-spacing:-.02em}
.pt-modal-card > .muted{margin:0 0 14px;font-size:13px;line-height:1.55}
.pt-field{display:grid;gap:6px;margin-bottom:12px;font-size:13px;font-weight:700}
.pt-field input{font:inherit;font-weight:500;padding:10px 12px;border:2px solid var(--brand-ink,#0A0A0A);border-radius:4px;background:var(--bg);color:var(--text)}
.pt-error{min-height:1.2em;margin:0 0 10px;color:var(--bad);font-size:13px}
.auth-forgot{margin:0 0 12px;font-size:12.5px;line-height:1.55}
.auth-forgot a{display:inline-block;margin-top:4px;font-weight:700;color:inherit;text-decoration:underline}
.review-stars{display:flex;gap:6px;margin:0 0 14px}
.review-stars button{width:42px;height:42px;border:2px solid var(--brand-ink,#0A0A0A);background:#fff;font-size:22px;line-height:1;color:#c4c4c4;cursor:pointer;box-shadow:2px 2px 0 var(--brand-ink,#0A0A0A)}
.review-stars button.on,.review-stars button:hover{color:#E6A700;background:#FFF6CC}
#reviewComment{width:100%;resize:vertical;min-height:72px;padding:10px 12px;border:2px solid var(--brand-ink,#0A0A0A);font:inherit;box-sizing:border-box}
.pt-modal-actions{display:flex;justify-content:flex-end;gap:8px;flex-wrap:wrap}
.cert-preview{width:min(520px,100%)}
.cert-sheet{margin:12px 0 16px;padding:18px 18px 16px;border:4px solid #0A0A0A;border-radius:0;background:#F4F0E6;box-shadow:10px 10px 0 #0A0A0A;position:relative}
.cert-sheet::before{content:"PASSED";position:absolute;top:12px;right:12px;background:#00E5C0;color:#0A0A0A;border:3px solid #0A0A0A;padding:4px 8px;font-size:11px;font-weight:900;letter-spacing:.08em}
.cert-sheet::after{content:"";position:absolute;left:0;top:0;width:100%;height:10px;background:#FFE500;border-bottom:3px solid #0A0A0A}
.cert-kicker{margin:14px 0 8px;font-size:11px;letter-spacing:.14em;font-weight:800;text-transform:uppercase}
.cert-label{margin:0;font-size:14px;color:var(--muted)}
.cert-name{margin:6px 0 10px;font-family:"Archivo Black",sans-serif;font-size:clamp(28px,5vw,40px);letter-spacing:-.03em;border-bottom:8px solid #FFE500;display:inline-block;padding-bottom:2px}
.cert-body,.cert-stats,.cert-date{margin:0 0 8px;line-height:1.5}
body.modal-open{overflow:hidden}
@media(max-width:900px){
  .auth-chip{max-width:100%;order:5;width:100%;justify-content:flex-end;padding-bottom:8px}
  .auth-user{max-width:7em}
}


/* v2.5.123 — stage certificates */
.cert-preview{width:min(560px,100%)}
.cert-sheet-mini{padding:14px 16px 12px!important;margin-bottom:14px!important;box-shadow:8px 8px 0 #0A0A0A!important}
.cert-sheet-mini .cert-name{font-size:clamp(22px,4vw,30px)!important;margin:2px 0 8px!important}
.cert-stage-list{display:grid;gap:10px;margin:0 0 14px}
.cert-stage{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:10px 12px;border:3px solid #0A0A0A;border-radius:0;background:var(--bg);box-shadow:4px 4px 0 #0A0A0A}
.cert-stage.is-earned{background:#FFE500;box-shadow:5px 5px 0 #0A0A0A}
.cert-stage-all{border-style:dashed;background:#FFFdf8}
.cert-stage-copy{display:grid;gap:2px;min-width:0}
.cert-stage-copy b{font-size:14px}
.cert-stage-copy span{font-size:12px;color:var(--muted);font-weight:500}
.cert-stage.is-earned .cert-stage-copy span{color:#0A0A0A}
.cert-dl{flex:0 0 auto;min-height:34px!important;padding:6px 12px!important;font-size:12px!important;border-radius:0!important;box-shadow:3px 3px 0 #0A0A0A}
.cert-dl:disabled{opacity:.45;cursor:not-allowed;box-shadow:none}


/* v2.5.123 — audit UI fixes */
@media(max-width:900px){
  header{flex-wrap:wrap!important;align-content:flex-start;row-gap:6px;padding-bottom:6px}
  :root{--header-h:118px}
  .auth-chip{
    order:20;
    width:100%;
    max-width:none;
    justify-content:flex-end;
    padding:0 0 2px;
    flex-wrap:nowrap;
    overflow-x:auto;
    -webkit-overflow-scrolling:touch
  }
  .auth-btn{flex:0 0 auto}
  .auth-user{max-width:6.5em}
  .layout{min-height:calc(100vh - var(--header-h))}
  aside{top:var(--header-h);height:calc(100vh - var(--header-h))}
  .mobile-overlay{inset:var(--header-h) 0 0}
  .bridge-banner{top:var(--header-h)!important}
  .sticky-head{top:var(--header-h)}
}
.pt-modal-card{max-height:min(90vh,820px);overflow:auto}


/* v2.5.123 — paywall + unlock */
.lock-flag{display:inline-block;margin-right:6px;font-style:normal}
#lessonNav button.locked[data-paywall="1"]{opacity:.75;cursor:pointer}
#lessonNav button.locked[data-paywall="1"]:hover{opacity:1}
.unlock-plans{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:12px 0}
.unlock-plan{border:2px solid #0A0A0A;padding:12px;background:var(--bg);display:grid;gap:4px}
.unlock-plan b{font-size:15px}
.unlock-plan span{font-family:"Archivo Black",sans-serif;font-size:22px}
.unlock-plan small{color:var(--muted);font-weight:500}
.unlock-status{margin:0 0 8px;font-weight:700}
.cert-stage .cert-print{margin-left:6px}


/* v2.5.123 — Consistency + fluency pass (landing ↔ classroom)
   Kill soft glass/blur, harden auth/cert/unlock chrome, unify tracking/easing. */
:root{
  --ease:cubic-bezier(0.16,1,0.3,1)!important
}
header{
  background:var(--panel)!important;
  backdrop-filter:none!important;
  border-bottom:var(--border-sm,4px solid var(--ink))!important
}
.sticky-head{
  background:var(--bg)!important;
  backdrop-filter:none!important;
  border-bottom:3px solid var(--ink)
}
.result-wrap .tabs{
  background:var(--panel)!important;
  backdrop-filter:none!important
}
.tour-card h2,
.lesson-head h1,
.practice-head h1{
  font-family:"Archivo Black","IBM Plex Sans",sans-serif!important;
  letter-spacing:var(--tracking-display,-.02em)!important
}
.tour-backdrop,
.pt-modal-backdrop,
.mobile-overlay{
  backdrop-filter:contrast(120%)!important;
  -webkit-backdrop-filter:contrast(120%)!important
}
.pt-modal-card,
.tour-card{
  border:var(--border-sm,4px solid var(--ink))!important;
  border-radius:0!important;
  box-shadow:var(--hard-shadow-sm,6px 6px 0 var(--ink))!important;
  letter-spacing:var(--tracking-body,.02em)
}
.pt-modal-card h2{
  letter-spacing:var(--tracking-display,-.02em)!important
}
.pt-field{letter-spacing:var(--tracking-ui,.04em)}
.pt-field input{
  border:var(--border-sm,4px solid var(--ink))!important;
  border-radius:0!important;
  letter-spacing:var(--tracking-body,.02em);
  transition:box-shadow .25s var(--ease),transform .25s var(--ease)
}
.pt-field input:focus{
  outline:0;
  box-shadow:4px 4px 0 var(--volt)
}
.pt-modal-actions .primary,
.pt-modal-actions .secondary,
.tour-card .primary,
.tour-card .secondary{
  border-radius:0!important;
  letter-spacing:var(--tracking-ui,.04em);
  transition:transform .25s var(--ease),box-shadow .25s var(--ease),background .25s var(--ease)
}
.auth-chip{gap:8px}
.auth-btn{
  border-radius:0!important;
  letter-spacing:var(--tracking-ui,.04em)!important;
  min-height:36px!important;
  transition:transform .25s var(--ease),box-shadow .25s var(--ease),background .25s var(--ease)!important
}
.auth-user{letter-spacing:var(--tracking-ui,.04em)}
.cert-badge{
  border-radius:0!important;
  border:3px solid var(--ink)!important;
  box-shadow:2px 2px 0 var(--ink)
}
.cert-stage,
.unlock-plan{
  border:var(--border-sm,4px solid var(--ink))!important;
  border-radius:0!important;
  box-shadow:4px 4px 0 var(--ink);
  transition:transform .25s var(--ease),box-shadow .25s var(--ease)
}
.unlock-plan:hover,
.cert-stage:hover{
  transform:translate(-2px,-2px);
  box-shadow:6px 6px 0 var(--ink)
}
.cert-sheet{
  border:var(--border,5px solid var(--ink))!important;
  border-radius:0!important;
  box-shadow:10px 10px 0 var(--ink)!important;
  background:#F4F0E6!important
}
.cert-name{letter-spacing:var(--tracking-display,-.02em)!important}
.cert-kicker{letter-spacing:var(--tracking-eyebrow,.12em)!important}
.unlock-plan span{letter-spacing:var(--tracking-display,-.02em)}
body.dark .pt-modal-card,
body.dark .tour-card,
body.dark .cert-stage,
body.dark .unlock-plan,
body.dark .cert-sheet{
  border-color:var(--line)!important;
  box-shadow:6px 6px 0 var(--line)!important
}
body.dark .pt-field input{border-color:var(--line)!important}
body.dark .sticky-head{border-bottom-color:var(--line)}
@media(max-width:900px){
  .auth-chip{
    gap:6px;
    padding:4px 0 6px;
    border-top:3px solid var(--ink);
    margin-top:2px
  }
  body.dark .auth-chip{border-top-color:var(--line)}
}

/* v2.5.123 — Account menu + unlock plan picker + header fluency */
.auth-chip{
  position:relative;
  display:inline-flex;
  align-items:center;
  max-width:none;
  flex-wrap:nowrap
}
.auth-trigger{
  display:inline-flex!important;
  align-items:center;
  gap:8px;
  min-height:42px!important;
  padding:8px 12px!important;
  font-size:13px!important;
  font-weight:700!important;
  letter-spacing:var(--tracking-ui,.04em)!important;
  border-radius:0!important
}
.auth-trigger .auth-user{
  max-width:10em;
  font-size:13px;
  color:var(--text)
}
.auth-chevron{flex:0 0 auto;transition:transform .25s var(--ease)}
.auth-trigger.is-open .auth-chevron{transform:rotate(180deg)}
.account-panel{
  position:absolute;
  right:0;
  top:calc(100% + 8px);
  z-index:450;
  display:flex;
  flex-direction:column;
  align-items:stretch;
  gap:0;
  min-width:200px;
  padding:0;
  background:var(--panel);
  border:4px solid var(--ink);
  box-shadow:8px 8px 0 var(--ink)
}
.account-panel[hidden]{display:none!important}
.account-panel .account-item{
  width:100%!important;
  justify-content:flex-start!important;
  border:0!important;
  border-radius:0!important;
  box-shadow:none!important;
  border-bottom:3px solid var(--ink)!important;
  min-height:44px!important;
  padding:10px 14px!important;
  font-size:13px!important;
  letter-spacing:var(--tracking-ui,.04em)!important
}
.account-panel .account-item:last-child{border-bottom:0!important}
.account-panel .account-item:hover{
  background:var(--warn)!important;
  transform:none!important
}
.account-panel .account-item.hidden{display:none!important}
.unlock-plan{
  font:inherit;
  text-align:left;
  cursor:pointer;
  color:inherit;
  appearance:none;
  -webkit-appearance:none
}
.unlock-plan.is-active{
  background:var(--warn)!important;
  box-shadow:6px 6px 0 var(--ink)!important;
  transform:translate(-2px,-2px)
}
.unlock-hint{margin:0 0 12px;font-size:13px;line-height:1.55;letter-spacing:var(--tracking-body,.02em)}
.unlock-hint code{
  font-size:.9em;
  font-weight:700;
  border:2px solid var(--ink);
  padding:.1em .35em;
  background:var(--panel2,#EDE8DC)
}
.unlock-paybox{
  margin:10px 0 14px;
  padding:12px 14px;
  border:2px solid var(--ink,#0A0A0A);
  box-shadow:3px 3px 0 var(--ink,#0A0A0A);
  background:color-mix(in srgb,var(--warn,#FFE500) 35%,var(--panel,#fff));
  font-size:13px;
  line-height:1.55;
  font-weight:600
}
.unlock-paybox-title{margin:0 0 6px;font-size:14px}
.unlock-paybox p{margin:0 0 4px}
.unlock-paybox p:last-child{margin-bottom:0}
.unlock-paybox code{
  font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  font-size:1.05em;
  font-weight:800;
  letter-spacing:.04em
}
body.dark .unlock-paybox{
  background:color-mix(in srgb,var(--volt,#00E5C0) 18%,var(--panel,#171f2e));
  border-color:var(--line);
  box-shadow:3px 3px 0 var(--line)
}
.unlock-order-list{margin:6px 0 0;padding-left:1.1em;list-style:disc}
.unlock-order-list li{margin-bottom:10px}
.unlock-tail-row{
  margin-top:8px;
  padding:10px 12px;
  border:2px dashed var(--ink,#0A0A0A);
  background:var(--panel,#fff);
  display:grid;
  gap:8px;
  max-width:320px
}
.unlock-tail-row .pt-field{margin:0}
.unlock-tail-row input{width:100%;letter-spacing:.12em;font-weight:800}
.unlock-tail-hint{margin:0;font-size:12px}
.unlock-tail-done{margin-top:6px;font-size:13px}
body.dark .unlock-tail-row{border-color:var(--line);background:var(--panel)}
@media(max-width:900px){
  :root{--header-h:72px}
  header{
    flex-wrap:nowrap!important;
    align-items:center;
    row-gap:0;
    padding-bottom:0
  }
  .auth-chip{
    order:0;
    width:auto;
    max-width:none;
    padding:0;
    margin:0;
    border-top:0;
    overflow:visible
  }
  .auth-trigger .auth-user{max-width:6.5em}
  .layout{min-height:calc(100vh - var(--header-h))}
  aside{top:var(--header-h);height:calc(100vh - var(--header-h))}
  .mobile-overlay{inset:var(--header-h) 0 0}
  .bridge-banner{top:var(--header-h)!important}
  .sticky-head{top:var(--header-h)}
}
body.dark .account-panel{
  border-color:var(--line);
  box-shadow:8px 8px 0 var(--line)
}
body.dark .account-panel .account-item{border-bottom-color:var(--line)!important}
body.dark .unlock-plan.is-active{box-shadow:6px 6px 0 var(--line)!important}

#engine.err,#engine.wait{cursor:pointer;text-decoration:underline;text-underline-offset:3px}

/* Language switch — Brutalist hard edge (v2.5.123) */
.lang-switch{
  display:inline-flex;
  border:3px solid var(--ink,#0A0A0A);
  border-radius:0!important;
  overflow:hidden;
  flex-shrink:0;
  box-shadow:3px 3px 0 var(--ink,#0A0A0A)
}
.lang-btn{
  appearance:none;border:0;background:transparent;
  color:var(--text,#1A2332);
  font:700 12px/1 "IBM Plex Sans",system-ui,sans-serif;
  padding:8px 10px;min-height:34px;cursor:pointer;
  letter-spacing:var(--tracking-ui,.04em);
  border-radius:0!important
}
.lang-btn+.lang-btn{border-left:3px solid var(--ink,#0A0A0A)}
.lang-btn.is-active{background:var(--warn,#FFE500);color:#0A0A0A}
body.dark .lang-switch{border-color:var(--line);box-shadow:3px 3px 0 var(--line)}
body.dark .lang-btn{color:var(--text)}
body.dark .lang-btn+.lang-btn{border-left-color:var(--line)}
body.dark .lang-btn.is-active{background:var(--volt,#00E5C0);color:#0A0A0A}
@media(max-width:900px){
  .lang-switch{box-shadow:2px 2px 0 var(--ink,#0A0A0A)}
  .lang-btn{padding:6px 8px;font-size:11px;min-height:32px}
}

/* v2.5.123 — Locate lesson + engine short label + shortcut hint */
.nav-search-row{
  display:flex;
  align-items:stretch;
  gap:8px;
  margin:0 0 10px
}
.nav-search-row .nav-search{flex:1;margin:0}
.nav-locate{
  flex:0 0 auto;
  min-height:42px!important;
  padding:8px 12px!important;
  font-size:12px!important;
  font-weight:700!important;
  letter-spacing:var(--tracking-ui,.04em)!important;
  border-radius:0!important;
  white-space:nowrap
}
.nav-locate:hover{
  background:var(--warn)!important;
  transform:translate(-2px,-2px);
  box-shadow:4px 4px 0 var(--ink)
}
.shortcut{
  font-size:12px;
  font-weight:700;
  letter-spacing:var(--tracking-ui,.04em);
  color:var(--muted);
  white-space:nowrap
}
@media(max-width:900px){
  #engine.pill[data-short]{
    font-size:0!important;
    letter-spacing:0!important;
    padding:6px 8px!important;
    min-width:3.2em;
    text-align:center
  }
  #engine.pill[data-short]::after{
    content:attr(data-short);
    font-size:10px;
    font-weight:800;
    letter-spacing:.06em;
    text-transform:uppercase
  }
  .home-link{padding:6px 8px!important;font-size:12px!important}
}
@media(max-width:560px){
  .shortcut{
    display:inline!important;
    font-size:11px;
    max-width:100%;
    white-space:normal
  }
  .editor-top>span:last-child{display:none}
}

/* v2.5.123 — Mobile UX: compact chrome, sticky runbar, safe areas */
html{
  -webkit-text-size-adjust:100%;
  text-size-adjust:100%
}
@media(max-width:900px){
  :root{--header-h:64px}
  body{
    padding-bottom:env(safe-area-inset-bottom,0px)
  }
  header{
    min-height:calc(var(--header-h) + env(safe-area-inset-top,0px))!important;
    padding-top:calc(9px + env(safe-area-inset-top,0px))!important;
    padding-left:max(10px,env(safe-area-inset-left,0px))!important;
    padding-right:max(10px,env(safe-area-inset-right,0px))!important;
    gap:6px!important
  }
  .header-actions{
    gap:4px!important;
    flex-wrap:nowrap;
    align-items:center;
    min-width:0
  }
  .brand .logo{font-size:clamp(1rem,4.2vw,1.2rem)!important}
  .brand .logo i{display:none}
  .header-actions > .home-link{display:none!important}
  .home-more{display:flex!important}
  .auth-trigger{
    min-height:40px!important;
    padding:6px 8px!important;
    max-width:7.5em
  }
  .auth-trigger .auth-user{
    max-width:4.8em;
    overflow:hidden;
    text-overflow:ellipsis;
    white-space:nowrap;
    font-size:12px!important
  }
  .lang-switch{box-shadow:none!important}
  .lang-btn{min-height:36px;padding:6px 7px}
  .icon-btn{
    width:40px;height:40px;min-width:40px;
    min-height:40px!important
  }
  #menuBtn{min-width:44px;min-height:44px}
  main{
    padding:0 14px max(64px,env(safe-area-inset-bottom,0px) + 48px)!important
  }
  .lesson-head h1,.practice-head h1{
    font-size:clamp(1.55rem,7vw,2.05rem)!important;
    line-height:1.15!important;
    letter-spacing:var(--tracking-display,-.02em)!important
  }
  .lesson-head p,.practice-head p{font-size:15px!important;line-height:1.65}
  .learning-trail{
    height:auto!important;
    min-height:40px;
    font-size:12px;
    overflow-x:auto;
    white-space:nowrap;
    -webkit-overflow-scrolling:touch
  }
  .workbench{margin-inline:0!important;gap:12px}
  .editor-wrap,.result-wrap{
    min-height:min(48vh,380px)!important
  }
  .panel{
    height:min(38vh,300px)!important;
    font-size:13px
  }
  .editor-wrap textarea{
    font-size:14px!important;
    line-height:1.5;
    min-height:180px
  }
  .runbar{
    position:sticky;
    bottom:0;
    z-index:15;
    display:flex;
    flex-wrap:wrap;
    align-items:center;
    gap:8px;
    background:var(--panel)!important;
    border-top:4px solid var(--ink);
    margin:0 -1px -1px;
    padding:10px 10px max(10px,env(safe-area-inset-bottom,0px))!important;
    box-shadow:0 -4px 0 color-mix(in srgb,var(--ink) 12%,transparent)
  }
  body.dark .runbar{border-top-color:var(--line)}
  .runbar .primary,.runbar .danger{
    min-height:48px!important;
    flex:1 1 auto
  }
  .run-button{min-width:0!important}
  .exercise-actions{
    display:flex;
    flex-wrap:wrap;
    gap:8px;
    width:100%
  }
  .exercise-actions .secondary{
    min-height:42px;
    flex:1 1 calc(50% - 8px)
  }
  .sticky-head{
    top:var(--header-h);
    padding-bottom:10px
  }
  .pt-modal-card,.tour-card{
    width:min(100%,calc(100vw - 24px))!important;
    max-height:min(88vh,720px);
    overflow:auto;
    -webkit-overflow-scrolling:touch;
    margin:max(8px,env(safe-area-inset-top,0px)) auto
  }
  .account-panel,.more-panel{
    max-width:min(240px,calc(100vw - 24px));
    right:0
  }
  aside{
    width:min(92vw,320px)!important;
    padding-bottom:max(16px,env(safe-area-inset-bottom,0px))
  }
  nav button{
    min-height:44px;
    padding:10px 12px
  }
  .pager{
    display:grid;
    grid-template-columns:1fr 1fr;
    gap:10px
  }
  .pager button{max-width:none!important;width:100%}
  .toast{
    left:12px;right:12px;
    max-width:none;
    bottom:max(16px,env(safe-area-inset-bottom,0px))
  }
}
@media(max-width:560px){
  .auth-trigger .auth-chevron{display:none}
  .auth-trigger .auth-user{max-width:3.6em;font-size:11px!important}
  .lesson-cta{
    display:grid!important;
    grid-template-columns:1fr 1fr;
    gap:8px;
    width:100%
  }
  .lesson-cta .reading-time{grid-column:1/-1}
  .syntax-lab{padding:14px!important;margin-inline:0!important}
  .nav-locate{padding:8px 10px!important;font-size:11px!important}
  .pass-banner{flex-direction:column;align-items:stretch}
  .pass-banner .primary{width:100%}
  .mismatch-banner{flex-direction:column;align-items:stretch}
  .lang-btn{padding:5px 6px;font-size:10px;min-height:34px}
}
/* Desktop: hide mobile-only more items */
@media(min-width:901px){
  .home-more{display:none!important}
}

/* v2.5.123 — iPhone Safari: notch, dvh, anti-zoom, keyboard, safe-area sync */
:root{
  --sat:env(safe-area-inset-top,0px);
  --sab:env(safe-area-inset-bottom,0px);
  --sal:env(safe-area-inset-left,0px);
  --sar:env(safe-area-inset-right,0px);
  --app-vh:100vh;
  --vvh:100vh
}
@supports(height:100dvh){
  :root{--app-vh:100dvh;--vvh:100dvh}
}
html{
  height:-webkit-fill-available;
  overscroll-behavior-y:none
}
@supports(height:100dvh){
  /* Prefer min-height: locking html to 100dvh jumps on iOS when the URL bar / keyboard resizes. */
  html{min-height:100dvh}
}
body{
  min-height:100vh;
  min-height:100dvh;
  min-height:-webkit-fill-available
}
button,.icon-btn,.lang-btn,.primary,.secondary,.danger,a.secondary,label.file,nav button{
  touch-action:manipulation;
  -webkit-tap-highlight-color:rgba(10,10,10,.1)
}

@media(max-width:900px){
  :root{
    --header-base:64px;
    --header-h:calc(var(--header-base) + var(--sat))
  }
  header{
    min-height:var(--header-h)!important;
    height:auto!important;
    /* border-box：sat 只計入一次，內容列約 --header-base */
    padding-top:var(--sat)!important;
    padding-bottom:0!important;
    padding-left:max(10px,var(--sal))!important;
    padding-right:max(10px,var(--sar))!important;
    box-sizing:border-box;
    align-items:center
  }
  .layout{
    min-height:calc(var(--app-vh) - var(--header-h))!important
  }
  aside{
    top:var(--header-h)!important;
    height:calc(var(--vvh) - var(--header-h))!important;
    max-height:calc(var(--vvh) - var(--header-h))!important;
    padding-left:max(0px,var(--sal));
    padding-bottom:max(20px,var(--sab))!important;
    -webkit-overflow-scrolling:touch;
    overscroll-behavior:contain
  }
  .mobile-overlay{
    inset:var(--header-h) 0 0!important
  }
  .bridge-banner{
    top:var(--header-h)!important;
    padding-left:max(12px,var(--sal));
    padding-right:max(12px,var(--sar))
  }
  .sticky-head{
    top:var(--header-h)!important
  }
  .tour{
    top:var(--header-h)!important;
    padding:max(12px,var(--sat)) 16px max(16px,var(--sab))
  }
  main{
    padding-left:max(14px,var(--sal))!important;
    padding-right:max(14px,var(--sar))!important;
    padding-bottom:max(72px,calc(var(--sab) + 56px))!important
  }
  /* iOS zooms inputs <16px — keep editor / forms readable without zoom jump */
  .editor-wrap textarea,
  .nav-search input,
  .pt-field input,
  #unlockCode,
  input[type="text"],
  input[type="email"],
  input[type="password"],
  input[type="search"]{
    font-size:16px!important;
    line-height:1.45
  }
  .editor-wrap,.result-wrap{
    min-height:min(42dvh,340px)!important;
    min-height:min(42vh,340px)
  }
  @supports(height:100dvh){
    .editor-wrap,.result-wrap{min-height:min(42dvh,340px)!important}
  }
  .panel{
    height:min(34dvh,280px)!important;
    height:min(34vh,280px);
    -webkit-overflow-scrolling:touch
  }
  @supports(height:100dvh){
    .panel{height:min(34dvh,280px)!important}
  }
  .runbar{
    position:sticky;
    bottom:0;
    z-index:15;
    padding:10px 10px max(12px,var(--sab))!important;
    /* Keep bar above home indicator; avoid iOS rubber-band covering CTA */
    transform:translateZ(0)
  }
  /* Soft keyboard open: don't pin runbar behind keyboard */
  body.kb-open .runbar{
    position:static;
    box-shadow:none
  }
  body.kb-open .sticky-head{
    position:static
  }
  .pt-modal{
    padding:max(10px,var(--sat)) 12px max(12px,var(--sab))!important;
    align-items:flex-start!important;
    overflow:auto;
    -webkit-overflow-scrolling:touch;
    overscroll-behavior:contain
  }
  .pt-modal-card,.tour-card{
    width:min(100%,calc(100vw - 24px - var(--sal) - var(--sar)))!important;
    max-height:calc(var(--vvh) - 24px)!important;
    margin:0 auto!important
  }
  .account-panel,.more-panel{
    max-width:min(260px,calc(100vw - 20px - var(--sar)));
    right:max(0px,calc(var(--sar) - 4px))
  }
  .toast{
    left:max(12px,var(--sal));
    right:max(12px,var(--sar));
    bottom:max(16px,calc(var(--sab) + 8px))
  }
  .skip-link:focus{
    top:max(8px,var(--sat));
    left:max(8px,var(--sal))
  }
}
@media(max-width:560px){
  :root{--header-base:58px}
  .header-actions .lang-switch{
    /* Keep language reachable but denser on SE-class widths */
    flex-shrink:0
  }
  #engine.pill{
    max-width:4.8em;
    overflow:hidden;
    text-overflow:ellipsis;
    white-space:nowrap
  }
  .workbench{
    gap:10px!important
  }
  .editor-wrap textarea{
    min-height:160px;
    padding:12px!important
  }
}
/* Standalone PWA (Add to Home Screen) — fill notch cleanly */
@media(display-mode:standalone){
  header{
    padding-top:var(--sat)!important
  }
}

/* v2.5.123 — PWA install banner */
.install-banner{
  position:fixed;
  left:max(12px,var(--sal,0px));
  right:max(12px,var(--sar,0px));
  bottom:max(12px,calc(var(--sab,0px) + 8px));
  z-index:260;
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:10px;
  padding:12px 14px;
  background:var(--panel,#FFFcf8);
  color:var(--ink,#0A0A0A);
  border:4px solid var(--ink,#0A0A0A);
  box-shadow:8px 8px 0 var(--ink,#0A0A0A);
}
.install-banner.hidden{display:none!important}
.install-copy{display:grid;gap:2px;min-width:0;flex:1 1 160px}
.install-copy b{
  font-family:"Archivo Black",sans-serif;
  font-size:1rem;
  letter-spacing:var(--tracking-logo,-.02em)
}
.install-copy span{
  font-size:13px;
  line-height:1.45;
  color:var(--muted,#3A3A3A);
  letter-spacing:var(--tracking-body,.02em)
}
.install-actions{display:flex;gap:8px;flex:0 0 auto}
.install-actions .primary,
.install-actions .secondary{
  min-height:44px!important;
  padding:8px 12px!important
}
@media(max-width:560px){
  .install-banner{padding:12px}
  .install-actions{width:100%}
  .install-actions .primary,
  .install-actions .secondary{flex:1 1 auto}
}

/* v2.5.123 — Fix mobile left peek / layout shift */
html,body{
  max-width:100%;
  overflow-x:clip
}
@media(max-width:900px){
  /* Sidebar was width≤320px but left:-300px → ~20px strip always visible */
  aside{
    --side-w:min(92vw,320px);
    width:var(--side-w)!important;
    left:0!important;
    transform:translateX(calc(-100% - 20px));
    visibility:hidden;
    pointer-events:none;
    box-shadow:none!important;
    padding-left:16px!important; /* don't add safe-area while off-screen */
    will-change:transform
  }
  aside.open{
    transform:translateX(0);
    visibility:visible;
    pointer-events:auto;
    box-shadow:12px 0 0 color-mix(in srgb,var(--ink,#0A0A0A) 18%,transparent)!important;
    padding-left:max(16px,var(--sal,0px))!important
  }
  .layout{
    grid-template-columns:1fr!important;
    width:100%;
    max-width:100%;
    overflow-x:clip
  }
  main{
    width:100%;
    max-width:100%;
    margin:0!important;
    padding-left:max(14px,var(--sal,0px))!important;
    padding-right:max(14px,var(--sar,0px))!important
  }
  header{
    width:100%;
    max-width:100%;
    overflow:hidden; /* clip brand-rail bleed */
    left:0;right:0
  }
  .brand-rail{
    margin-left:0!important;
    margin-right:0!important;
    width:100%!important;
    max-width:100%
  }
  /* Hard shadows must not widen the scrollport */
  .workbench,.syntax-lab,.editor-wrap,.result-wrap,.progress-box{
    max-width:100%
  }
  body::before{
    left:0;right:0;width:100%;
    max-width:100vw
  }
}
@supports not (overflow:clip){
  html,body{overflow-x:hidden}
}

/* v2.5.123 — LINE contact FAB + menu link */
.line-fab{
  position:fixed;
  right:max(16px,var(--sar,0px));
  bottom:max(16px,calc(var(--sab,0px) + 12px));
  z-index:270;
  display:inline-flex;
  align-items:center;
  gap:10px;
  min-height:52px;
  padding:10px 16px 10px 12px;
  border:3px solid var(--ink,#0A0A0A);
  background:#06C755;
  color:#fff;
  text-decoration:none;
  font-weight:800;
  font-size:14px;
  letter-spacing:.02em;
  box-shadow:6px 6px 0 var(--ink,#0A0A0A);
  transition:transform .15s var(--ease,ease),box-shadow .15s var(--ease,ease)
}
.line-fab:hover{
  transform:translate(-2px,-2px);
  box-shadow:8px 8px 0 var(--ink,#0A0A0A);
  color:#fff
}
.line-fab:active{
  transform:translate(2px,2px);
  box-shadow:2px 2px 0 var(--ink,#0A0A0A)
}
.line-fab .line-icon{flex:0 0 auto;display:block}
.line-fab-label{white-space:nowrap}
.line-menu-link{
  display:inline-flex!important;
  align-items:center;
  gap:8px;
  text-decoration:none!important;
  color:inherit
}
.line-menu-link .line-icon{color:#06C755;flex:0 0 auto}
body.dark .line-fab{
  border-color:var(--line,#2A3531);
  box-shadow:6px 6px 0 var(--line,#2A3531)
}
body.dark .line-fab:hover{box-shadow:8px 8px 0 var(--line,#2A3531)}
body.dark .line-menu-link .line-icon{color:#06C755}
@media(max-width:560px){
  .line-fab{
    padding:12px;
    border-radius:0;
    min-width:52px;
    justify-content:center
  }
  .line-fab-label{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);border:0}
}

.elective-flag{display:inline-block;margin-right:4px;padding:0 4px;border-radius:4px;font-size:10px;font-style:normal;font-weight:800;letter-spacing:.04em;background:#e8f0fe;color:#1a56db;vertical-align:middle}
.dark .elective-flag{background:#1e3a5f;color:#93c5fd}

.legal-alert{color:#c62828;font-weight:800}
.cert-lead .legal-alert{color:#c62828;font-weight:800}
body.dark .legal-alert,body.dark .cert-lead .legal-alert{color:#ff8a80}

.compat-banner{margin:0;padding:12px 16px;background:#ffebee;color:#b71c1c;border-bottom:2px solid #c62828;font-size:14px;line-height:1.5}
.compat-banner.hidden{display:none!important}
.compat-banner b{display:block;margin-bottom:6px;font-weight:800}
.compat-banner ul{margin:0 0 8px;padding-left:1.2rem}
.compat-banner .compat-hint{margin:0;font-size:13px;color:#8e0000}
body.dark .compat-banner{background:#3b1515;color:#ffcdd2;border-bottom-color:#ef5350}
body.dark .compat-banner .compat-hint{color:#ef9a9a}
@media(max-width:900px){
  input,textarea,select{font-size:16px!important}
  button.primary,button.secondary,#runBtn,#hintBtn{min-height:44px}
}

/* v2.5.123 — Sync classroom with landing Brutalist polish (v2.5.123) */
:root{
  --border-lg:6px solid var(--ink);
  --hard-shadow-lg:16px 16px 0 var(--ink);
  --shadow-lg:var(--hard-shadow-lg);
  --tracking-display:-.02em;
  --tracking-logo:-.02em;
  --tracking-body:.02em;
  --tracking-ui:.04em;
  --tracking-eyebrow:.12em
}
body.dark{
  --border-lg:6px solid #F4F0E6;
  --hard-shadow-lg:16px 16px 0 #F4F0E6;
  --shadow-lg:var(--hard-shadow-lg)
}
body::before{opacity:.09}
body.dark::before{opacity:.14}
::selection{background:var(--warn);color:var(--ink)}
:focus-visible{
  outline:4px solid var(--volt,#00E5C0)!important;
  outline-offset:3px
}
header{
  background:color-mix(in srgb,var(--paper,#F4F0E6) 55%,transparent)!important;
  backdrop-filter:contrast(120%)!important;
  -webkit-backdrop-filter:contrast(120%)!important;
  border-bottom:var(--border,5px solid var(--ink))!important;
  box-shadow:none!important
}
body.dark header{
  background:color-mix(in srgb,#0E0E0E 70%,transparent)!important
}
.sticky-head{
  background:var(--paper,#F4F0E6)!important;
  backdrop-filter:contrast(120%)!important;
  -webkit-backdrop-filter:contrast(120%)!important;
  border-bottom:3px solid var(--ink)
}
body.dark .sticky-head{background:var(--panel)!important;border-bottom-color:var(--line)}
.result-wrap .tabs{
  background:var(--panel2)!important;
  backdrop-filter:contrast(120%)!important;
  -webkit-backdrop-filter:contrast(120%)!important
}
.primary:hover,.secondary:hover,label.file:hover,.icon-btn:hover{
  box-shadow:var(--hard-shadow-lg)!important
}
.workbench .editor-wrap,
.workbench .result-wrap,
.syntax-lab,
.progress-box,
.tour-card,
.auth-modal .modal-card,
.unlock-modal .modal-card,
.cert-modal .modal-card{
  box-shadow:var(--hard-shadow)!important
}
.workbench .editor-wrap:focus-within,
.syntax-lab:hover,
.progress-box:hover{
  box-shadow:var(--hard-shadow-lg)!important
}
.lesson-head h1,.practice-head h1{
  line-height:.92;
  letter-spacing:var(--tracking-display);
  text-wrap:balance
}
.brand b{letter-spacing:var(--tracking-logo)}
.primary,.secondary,.danger,label.file,.icon-btn,.auth-chip button,.account-menu button{
  letter-spacing:var(--tracking-ui)
}
.pass-banner{
  border:var(--border-sm,4px solid var(--ink))!important;
  box-shadow:var(--hard-shadow-sm)!important;
  border-left:6px solid var(--volt,#00E5C0)!important
}
.unlock-plan.is-active{
  border-width:6px!important;
  box-shadow:var(--hard-shadow-lg)!important;
  position:relative
}
.unlock-plan.is-active::before{
  content:"WARNING · BEST VALUE";
  position:absolute;top:-.75rem;right:.75rem;
  background:var(--signal,#FF3B30);color:#fff;
  border:3px solid var(--ink);
  font:700 .62rem/1 "IBM Plex Sans",system-ui,sans-serif;
  letter-spacing:.1em;
  padding:.3rem .5rem;
  box-shadow:4px 4px 0 var(--ink);
  z-index:2
}
.tour-backdrop,.modal-backdrop,#authBackdrop,#unlockBackdrop,#certBackdrop{
  backdrop-filter:contrast(120%)!important;
  -webkit-backdrop-filter:contrast(120%)!important
}
.mobile-overlay{
  backdrop-filter:contrast(120%)!important;
  -webkit-backdrop-filter:contrast(120%)!important
}
.install-banner{
  border:4px solid var(--ink)!important;
  border-radius:0!important;
  box-shadow:8px 8px 0 var(--ink)!important;
  background:var(--warn)!important;
  color:var(--ink)!important;
  backdrop-filter:contrast(120%)
}
.install-banner .primary{
  background:var(--ink)!important;
  color:var(--warn)!important
}
.account-menu,.more-menu{
  border:4px solid var(--ink)!important;
  box-shadow:8px 8px 0 var(--ink)!important;
  border-radius:0!important;
  background:var(--paper,#F4F0E6)!important
}
.account-menu button,.more-menu button,.more-menu a,.account-menu a{
  border-radius:0!important;
  border-bottom:2px solid var(--ink);
  font-weight:700;
  letter-spacing:var(--tracking-ui,.04em)
}
.account-menu button:last-child,.more-menu button:last-child,.more-menu a:last-child{
  border-bottom:0
}

/* v2.5.123 — Consistency sweep: kill leftover soft UI vs landing */
.level-badge,.unit-count,.level-count,.domain-badge,.elective-flag,.quiz-flag,
.compat-banner,.toast,.auth-chip,.account-menu,.more-menu,
.install-banner,.nav-search input,.search-empty{
  border-radius:0!important
}
.level-badge,.unit-count,.level-count,.domain-badge,.elective-flag,.quiz-flag{
  border:3px solid var(--ink)!important;
  box-shadow:3px 3px 0 var(--ink);
  background:var(--warn)!important;
  color:var(--ink)!important;
  letter-spacing:var(--tracking-eyebrow,.12em);
  text-transform:uppercase;
  font-weight:800
}
.elective-flag{background:var(--volt)!important}
.quiz-flag{background:var(--signal)!important;color:#fff!important}
.toast{
  border:4px solid var(--ink)!important;
  box-shadow:8px 8px 0 var(--ink)!important;
  background:var(--ink)!important;
  color:var(--warn)!important;
  font-weight:700;
  letter-spacing:var(--tracking-ui,.04em)
}
.compat-banner{
  border:0;
  border-bottom:5px solid var(--ink)!important;
  background:var(--signal)!important;
  color:#fff!important;
  font-family:"IBM Plex Sans",system-ui,sans-serif;
  box-shadow:none
}
.compat-banner .compat-hint{color:#fff!important;opacity:.92}
.tour-card h2,.lesson-head h1,.practice-head h1,.brand b{
  font-family:"Archivo Black","IBM Plex Sans",system-ui,sans-serif!important
}
.tour-card{
  border:var(--border,5px solid var(--ink))!important;
  box-shadow:var(--hard-shadow,12px 12px 0 var(--ink))!important
}
.learning-trail{
  border-bottom:3px solid var(--ink)!important;
  letter-spacing:var(--tracking-ui,.04em);
  text-transform:uppercase;
  font-weight:700
}
#nextExerciseBtn.nudge{
  animation:nudge-hard 1.1s var(--ease) 2
}
@keyframes nudge-hard{
  0%,100%{transform:none;box-shadow:var(--hard-shadow-sm,6px 6px 0 var(--ink))}
  40%{transform:translate(-3px,-3px);box-shadow:var(--hard-shadow-lg,16px 16px 0 var(--ink))}
}
@media(prefers-reduced-motion:reduce){
  #nextExerciseBtn.nudge{animation:none}
}
body.dark .level-badge,body.dark .unit-count,body.dark .level-count,body.dark .domain-badge{
  border-color:var(--line)!important;
  box-shadow:3px 3px 0 var(--line)
}
body.dark .toast{
  border-color:var(--line)!important;
  box-shadow:8px 8px 0 var(--line)!important
}
/* v2.5.123 — Reduce yellow flood; restore color diversity */
.level-badge,.unit-count,.level-count,.domain-badge{
  border:3px solid var(--ink)!important;
  border-radius:0!important;
  box-shadow:3px 3px 0 var(--ink)!important;
  background:var(--volt)!important;
  color:var(--ink)!important;
  font-weight:800;
  letter-spacing:.06em
}
.level-group[data-level="初級"] .level-badge,
.level-group[data-level="Beginner"] .level-badge{
  background:var(--volt)!important;color:var(--ink)!important
}
.level-group[data-level="中級"] .level-badge,
.level-group[data-level="Intermediate"] .level-badge{
  background:#fff!important;color:var(--ink)!important
}
.level-group[data-level="高級"] .level-badge,
.level-group[data-level="Advanced"] .level-badge{
  background:var(--warn)!important;color:var(--ink)!important
}
.level-group[data-level="專業"] .level-badge,
.level-group[data-level="Pro"] .level-badge{
  background:var(--signal)!important;color:#fff!important
}
.elective-flag{
  border:3px solid var(--ink)!important;
  border-radius:0!important;
  background:#fff!important;
  color:var(--ink)!important;
  box-shadow:3px 3px 0 var(--ink)
}
.quiz-flag{
  border:3px solid var(--ink)!important;
  border-radius:0!important;
  background:var(--signal)!important;
  color:#fff!important;
  box-shadow:3px 3px 0 var(--ink)
}
.toast{
  border:4px solid var(--ink)!important;
  box-shadow:8px 8px 0 var(--ink)!important;
  background:var(--ink)!important;
  color:var(--volt)!important;
  border-radius:0!important
}
.install-banner{
  background:var(--volt)!important;
  color:var(--ink)!important;
  border:4px solid var(--ink)!important;
  box-shadow:8px 8px 0 var(--ink)!important
}
.install-banner .primary{
  background:var(--ink)!important;
  color:var(--volt)!important
}
.section-kicker,.tour-kicker{
  background:var(--ink)!important;
  color:var(--volt)!important;
  border:3px solid var(--ink)!important
}
.secondary:hover,label.file:hover,.icon-btn:hover{
  background:var(--volt)!important
}
.unit-count,.level-count{
  background:var(--panel2)!important;
  color:var(--ink)!important
}
body.dark .toast{color:var(--volt)!important}
body.dark .level-badge,body.dark .unit-count,body.dark .level-count,body.dark .domain-badge{
  border-color:var(--line)!important;
  box-shadow:3px 3px 0 var(--line)!important
}

#lessonBody .term-tip,#lessonIntro .term-tip,.purpose-box .term-tip{
  position:relative;cursor:help;border-bottom:1.5px dashed var(--primary);
  color:inherit;font-weight:650;padding:0 .05em;
}
#lessonBody .term-tip::after,#lessonIntro .term-tip::after,.purpose-box .term-tip::after{
  content:attr(data-tip);position:absolute;left:50%;bottom:calc(100% + 8px);transform:translateX(-50%);
  width:min(280px,70vw);padding:8px 10px;border-radius:8px;background:#1a2332;color:#fff;
  font-size:12px;font-weight:500;line-height:1.45;letter-spacing:0;opacity:0;pointer-events:none;
  transition:opacity .15s ease;z-index:40;box-shadow:0 8px 24px #0004;text-align:left;
}
#lessonBody .term-tip:hover::after,#lessonBody .term-tip:focus::after,#lessonBody .term-tip.is-open::after,
#lessonIntro .term-tip:hover::after,#lessonIntro .term-tip:focus::after,#lessonIntro .term-tip.is-open::after,
.purpose-box .term-tip:hover::after,.purpose-box .term-tip:focus::after,.purpose-box .term-tip.is-open::after{opacity:1}
body.dark #lessonBody .term-tip::after,body.dark #lessonIntro .term-tip::after,body.dark .purpose-box .term-tip::after{background:#0a0e0c;border:1px solid var(--line)}
@media(max-width:900px){
  #lessonBody .term-tip::after,#lessonIntro .term-tip::after,.purpose-box .term-tip::after{width:min(260px,82vw)}
}

/* Glossary compact popover near FAB */
.glossary-pop{
  position:fixed;
  right:max(16px,var(--sar,0px));
  bottom:calc(max(16px,calc(var(--sab,0px) + 12px)) + 128px);
  z-index:280;
  width:min(280px,calc(100vw - 32px));
  padding:10px 12px 12px;
  background:var(--panel,#fff);
  color:var(--text);
  border:3px solid var(--ink,#0A0A0A);
  box-shadow:6px 6px 0 var(--ink,#0A0A0A);
  display:flex;flex-direction:column;gap:6px
}
.glossary-pop.hidden{display:none!important}
.glossary-pop-head{display:flex;align-items:center;justify-content:space-between;gap:8px}
.glossary-pop-title{font-weight:800;font-size:13px;letter-spacing:.02em}
.glossary-close{width:32px;height:32px;padding:0}
.glossary-search-field{margin:0}
.glossary-search-field input{
  width:100%;box-sizing:border-box;padding:8px 10px;border:2px solid var(--ink,#0A0A0A);
  border-radius:4px;font:inherit;font-size:14px;background:var(--panel);color:var(--text)
}
.glossary-count{margin:0;font-size:11px;line-height:1.3;min-height:1.2em}
.glossary-list{margin:0;max-height:140px;overflow:auto;display:grid;gap:6px}
.glossary-list:empty{display:none}
.glossary-item{
  margin:0;padding:0;border:1.5px solid var(--line);border-radius:4px;background:var(--panel2,#f8fafc);
  overflow:hidden
}
.glossary-term{
  list-style:none;cursor:pointer;display:flex;align-items:center;justify-content:space-between;gap:8px;
  margin:0;padding:8px 10px;font-size:13px;font-weight:750;color:var(--primary,#635bff);
  user-select:none
}
.glossary-term::-webkit-details-marker{display:none}
.glossary-chevron{flex:0 0 auto;font-size:11px;color:var(--muted);transition:transform .15s ease}
.glossary-item[open] .glossary-chevron{transform:rotate(180deg)}
.glossary-def{margin:0;padding:0 10px 10px;font-size:12px;line-height:1.45;color:var(--text);border-top:1px dashed var(--line)}
.glossary-item[open] .glossary-def{padding-top:8px}
body.dark .glossary-pop{border-color:var(--line);box-shadow:6px 6px 0 var(--line)}
body.dark .glossary-item{background:#121a28;border-color:var(--line)}
body.dark .glossary-search-field input{border-color:var(--line)}
@media(max-width:560px){
  .glossary-pop{bottom:calc(max(16px,calc(var(--sab,0px) + 12px)) + 128px);width:min(260px,calc(100vw - 24px))}
}

/* Glossary FAB — stacked above LINE contact FAB */
.glossary-fab{
  position:fixed;
  right:max(16px,var(--sar,0px));
  bottom:calc(max(16px,calc(var(--sab,0px) + 12px)) + 64px);
  z-index:270;
  display:inline-flex;
  align-items:center;
  gap:10px;
  min-height:52px;
  padding:10px 16px 10px 12px;
  border:3px solid var(--ink,#0A0A0A);
  background:var(--volt,#C8F542);
  color:var(--ink,#0A0A0A);
  font:inherit;
  font-weight:800;
  font-size:14px;
  letter-spacing:.02em;
  box-shadow:6px 6px 0 var(--ink,#0A0A0A);
  cursor:pointer;
  transition:transform .15s var(--ease,ease),box-shadow .15s var(--ease,ease)
}
.glossary-fab:hover{
  transform:translate(-2px,-2px);
  box-shadow:8px 8px 0 var(--ink,#0A0A0A)
}
.glossary-fab:active{
  transform:translate(2px,2px);
  box-shadow:2px 2px 0 var(--ink,#0A0A0A)
}
.glossary-fab-icon{flex:0 0 auto;display:block}
.glossary-fab-label{white-space:nowrap}
body.dark .glossary-fab{
  border-color:var(--line,#2A3531);
  box-shadow:6px 6px 0 var(--line,#2A3531);
  background:#c8f542;color:#0a0a0a
}
body.dark .glossary-fab:hover{box-shadow:8px 8px 0 var(--line,#2A3531)}
@media(max-width:560px){
  .glossary-fab{
    padding:12px;
    border-radius:0;
    min-width:52px;
    justify-content:center;
    bottom:calc(max(16px,calc(var(--sab,0px) + 12px)) + 64px)
  }
  .glossary-fab-label{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);border:0}
}