:root{--bg:#0a1018;--surface:#101a25;--surface2:#162332;--ink:#eef4fb;--muted:#acbaca;--faint:#8094aa;--line:#293b4e;--gold:#f8cc60;--cyan:#62d9ce;--purple:#b6a0ff;--green:#85dfac;--red:#ff8e9e;--code:#0b1420;--mono:ui-monospace,SFMono-Regular,Consolas,monospace;--sans:Inter,ui-sans-serif,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;color-scheme:dark}
html[data-theme=light]{--bg:#f0f3f6;--surface:#fff;--surface2:#e9eff5;--ink:#162537;--muted:#4f6173;--faint:#5a6d81;--line:#cbd7e3;--gold:#946600;--cyan:#007a71;--purple:#7350c6;--green:#147647;--red:#b8314c;--code:#f6f8fb;color-scheme:light}
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.topbar{height:72px;position:sticky;top:0;z-index:20;background:var(--bg);border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;gap:16px;padding:0 28px}.brand{display:flex;gap:11px;align-items:center;text-decoration:none;color:var(--ink)}.brandmark{width:35px;height:35px;border-radius:9px;background:#f8cc60;color:#121821;font-weight:800;display:grid;place-items:center}.brand strong{font-size:11px;letter-spacing:1.4px;display:block}.brand small{font-size:11px;color:var(--faint);display:block}.topnav{display:flex;gap:8px;align-items:center;flex-wrap:wrap;justify-content:flex-end}.topnav a{font-size:12px;text-decoration:none;color:var(--muted);padding:8px 11px;border:1px solid var(--line);border-radius:8px;white-space:nowrap}.topnav a:hover{border-color:var(--faint);background:var(--surface2)}.topnav a[aria-current=page]{color:var(--gold);border-color:var(--gold);background:transparent}.topnav a.build-link{color:var(--cyan)}.topnav button{padding:6px 10px}
.layout{display:grid;grid-template-columns:244px minmax(0,1fr);max-width:1680px;margin:auto}.sidebar{padding:25px 18px;border-right:1px solid var(--line);position:sticky;top:72px;height:calc(100vh - 72px);overflow:auto;scrollbar-width:thin}.side-label{font-size:11px;color:var(--muted);margin:9px 0}.side-group{font-size:10px;color:var(--faint);text-transform:uppercase;letter-spacing:1px;margin:23px 7px 8px;font-weight:700}.lesson-link{display:flex;align-items:center;gap:10px;padding:9px 8px;border:1px solid transparent;border-radius:8px;color:var(--muted);text-decoration:none;line-height:1.4;font-size:12px;margin:2px 0}.lesson-link .num{font:11px var(--mono);color:var(--faint);width:19px;flex-shrink:0}.lesson-link span:nth-child(2){flex:1}.lesson-link:hover{background:var(--surface2)}.lesson-link[aria-current=page]{border-color:color-mix(in srgb,var(--gold) 38%,var(--line));background:color-mix(in srgb,var(--gold) 7%,var(--surface));color:var(--ink)}.lesson-link[aria-current=page] .num{color:var(--gold)}.done{color:var(--green);font-size:12px}.progress{height:4px;background:var(--surface2);border-radius:4px;margin:12px 0}.progress i{display:block;height:100%;background:var(--cyan);border-radius:4px}.saved{font-size:11px;color:var(--faint)}main{min-width:0;padding:28px 36px 50px}.lesson-head{display:flex;justify-content:space-between;gap:20px;align-items:flex-end;margin:17px 0 23px}.lesson-head h1{margin:7px 0 10px}.lesson-head p{max-width:750px;font-size:14px;color:var(--muted)}.lesson-meta{white-space:nowrap;color:var(--faint);font-size:11px}.breadcrumb{font-size:11px;color:var(--faint);display:flex;gap:9px;align-items:center}.breadcrumb a{color:var(--muted)}.stages{display:grid;grid-template-columns:repeat(5,1fr);border-bottom:1px solid var(--line);gap:7px;margin-bottom:25px}.stages button{border:0;border-bottom:2px solid transparent;border-radius:0;background:none;color:var(--faint);padding:13px 5px;justify-content:flex-start;gap:9px}.stages button[aria-current=step]{border-bottom-color:var(--gold);color:var(--ink)}.stage-number{font:10px var(--mono);border:1px solid var(--line);width:23px;height:23px;border-radius:50%;display:grid;place-items:center;flex-shrink:0}.stages button[aria-current=step] .stage-number{background:var(--gold);color:var(--bg);border-color:var(--gold)}.learning-grid{display:grid;grid-template-columns:1.08fr .92fr;gap:22px;align-items:start}.panel{background:var(--surface);border:1px solid var(--line);border-radius:15px;min-width:0;overflow:hidden}.panel-pad{padding:26px}.panel-label{font-size:10px;letter-spacing:1.2px;color:var(--faint);text-transform:uppercase;border-bottom:1px solid var(--line);padding:13px 20px;display:flex;align-items:center;justify-content:space-between;gap:12px}.explanation{font-size:16px;line-height:1.85;color:var(--muted);margin:14px 0 22px}.callout{padding:16px 18px;border-left:3px solid var(--gold);background:color-mix(in srgb,var(--gold) 5%,var(--surface));font-size:14px;border-radius:0 9px 9px 0;margin:20px 0}.code{padding:22px;background:var(--code);color:var(--cyan)}.terms{margin-top:19px}.terms details{padding:12px 0;border-top:1px solid var(--line)}summary{font-size:13px;font-weight:650}details p,details li{font-size:13px;color:var(--muted);margin-top:8px}.supply{font-size:12px;color:var(--faint);margin-top:17px}.action-row{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-top:25px;flex-wrap:wrap}.action-row .muted{font-size:12px}.trace{padding:23px}.trace-controls{display:flex;align-items:center;justify-content:space-between;margin-bottom:24px;gap:12px}.trace-controls span{font:11px var(--mono);color:var(--faint)}.trace-controls div{display:flex;gap:6px}.trace-track{display:grid;grid-template-columns:repeat(4,1fr);gap:7px;margin-bottom:25px}.trace-track button{height:5px;padding:0;border:0;border-radius:3px;background:var(--surface2)}.trace-track button.past{background:var(--cyan)}.trace-track button.active{background:var(--gold)}.trace-heading{margin:8px 0 24px;font-size:25px}.state-pair{display:grid;grid-template-columns:1fr;gap:13px}.state-cell{padding:18px;border-radius:10px;border:1px solid var(--line);background:var(--code)}.state-cell .eyebrow{color:var(--faint);margin-bottom:9px}.state-cell pre{color:var(--purple);font-size:15px}.state-cell.output{border-color:color-mix(in srgb,var(--cyan) 40%,var(--line))}.state-cell.output pre{color:var(--cyan);font-size:20px}.trace-note{font-size:14px;color:var(--muted);margin-top:20px;min-height:55px}.trace-list{margin:15px 0 0;padding:0;list-style:none}.trace-list li{padding:13px 0;border-bottom:1px solid var(--line);display:flex;gap:13px;font-size:13px;color:var(--muted)}.trace-list b{font:12px var(--mono);color:var(--gold);padding-top:3px}.question{font-size:22px;line-height:1.5;margin:12px 0 24px;max-width:830px}.choices{display:grid;gap:11px}.choice{justify-content:flex-start;text-align:left;min-height:53px;background:var(--code);font:13px/1.7 var(--mono);padding:13px 17px}.choice.selected{border-color:var(--gold)}.choice.correct{border-color:var(--green);background:color-mix(in srgb,var(--green) 7%,var(--surface))}.choice.wrong{border-color:var(--red)}.choice span{color:var(--faint);margin-right:8px}.feedback{padding:16px 18px;border:1px solid var(--line);border-radius:9px;background:var(--surface2);font-size:14px;margin-top:16px}.feedback.good{border-color:var(--green);color:var(--green)}.feedback.bad{border-color:var(--red)}.feedback:empty{display:none}.practice-grid{display:grid;grid-template-columns:minmax(240px,.7fr) minmax(0,1.3fr);gap:22px}.practice-grid h2{font-size:22px;margin:10px 0}.task{font-size:14px;color:var(--muted);margin:13px 0 20px}.modes{display:flex;gap:7px;margin-bottom:15px}.modes button{font-size:12px}.modes button.active{color:var(--gold);border-color:var(--gold)}textarea{display:block;width:100%;min-height:360px;resize:vertical;padding:21px;background:var(--code);color:var(--ink);border:0;tab-size:2;font:13px/1.8 var(--mono);border-radius:0}textarea:focus{outline-offset:-3px}.editor-footer{border-top:1px solid var(--line);padding:13px 17px;display:flex;gap:9px;align-items:center;flex-wrap:wrap}.editor-footer span{margin-left:auto;color:var(--faint);font-size:11px}.hint-list{margin-top:10px}.hint-list p{font-size:13px;color:var(--muted);margin:10px 0}.hint-actions{display:flex;flex-wrap:wrap;gap:8px}.hint-actions button{font-size:12px}.reference{margin-top:19px}.reference summary{padding:14px;border:1px solid var(--line);border-radius:8px}.reference pre{margin-top:10px;border:1px solid var(--line);border-radius:8px;padding:16px;max-height:500px;overflow:auto}.results{margin-top:18px}.test-result{padding:14px 18px;border-top:1px solid var(--line);font-size:12px}.test-result strong{font-size:13px}.test-result p{margin-top:5px;color:var(--muted);white-space:pre-wrap;overflow-wrap:anywhere}.pass-mark{color:var(--green)}.fail-mark{color:var(--red)}.console{font:12px/1.7 var(--mono);padding:15px 18px;color:var(--muted);white-space:pre-wrap;max-height:220px;overflow:auto}.edge-list{padding-left:18px;margin:15px 0}.edge-list li{padding:5px 0;font-size:13px;color:var(--muted)}.review-checks{display:grid;gap:9px;margin:20px 0;color:var(--muted);font-size:13px}.review-checks div{padding:11px 14px;border:1px solid var(--line);border-radius:8px}.mobile-lessons{display:none}.footer-note{font-size:11px;color:var(--faint);margin-top:30px;border-top:1px solid var(--line);padding-top:15px}
.course-main{max-width:1210px;margin:0 auto;padding:40px 30px 70px}.course-intro{display:grid;grid-template-columns:1.2fr .8fr;gap:35px;align-items:center;margin-bottom:32px}.course-intro h1{font-size:clamp(34px,4.2vw,55px);margin:10px 0 15px;max-width:650px}.course-intro p{color:var(--muted);max-width:640px}.course-visual{display:flex;gap:8px;align-items:center;justify-content:center}.course-visual b{font:24px var(--mono);width:74px;height:84px;border:1px solid var(--line);border-radius:12px;display:grid;place-items:center;background:var(--surface);color:var(--gold)}.course-visual b:nth-of-type(2){color:var(--purple)}.course-visual b:nth-of-type(3){color:var(--cyan)}.course-visual span{color:var(--faint)}.course-start{display:flex;gap:9px;margin-top:21px;flex-wrap:wrap}.part-one{display:grid;grid-template-columns:1fr 1fr;gap:30px;padding:28px;background:var(--surface);border:1px solid var(--line);border-radius:15px;margin:23px 0 35px}.part-one h2{margin:8px 0 12px}.part-one p{font-size:14px;color:var(--muted)}.part-one ul{list-style:none;padding:0;margin:0;display:grid;grid-template-columns:1fr 1fr;gap:9px 18px;color:var(--muted);font-size:12px}.part-one li{border-bottom:1px solid var(--line);padding:6px 0}.course-section-title{margin:10px 0 24px}.course-section-title h2{margin:7px 0 10px}.course-section-title p{color:var(--muted);font-size:14px}.chapter-grid{display:grid;grid-template-columns:1fr 1fr;gap:18px}.chapter{border:1px solid var(--line);border-radius:14px;background:var(--surface);padding:23px;position:relative}.chapter h3{font-size:21px;margin:7px 0 10px}.chapter p{color:var(--muted);font-size:13px;min-height:43px}.chapter ul{list-style:none;margin:17px 0 15px;padding:0}.chapter li+li{border-top:1px solid var(--line)}.chapter a{display:flex;justify-content:space-between;padding:9px 0;text-decoration:none;font-size:13px;color:var(--ink)}.chapter a:hover{color:var(--cyan)}.chapter .prereq{font-size:11px;color:var(--faint);border-top:1px solid var(--line);padding-top:12px}.chapter:last-child{grid-column:1/-1}.chapter:last-child ul{display:grid;grid-template-columns:repeat(3,1fr);gap:22px}.chapter:last-child li+li{border:0}.storage-notice{position:fixed;bottom:16px;left:16px;right:16px;background:var(--surface2);padding:12px;border:1px solid var(--red);border-radius:9px;z-index:50;font-size:13px}.storage-notice[hidden]{display:none}
@media(min-width:1450px){main{padding:32px 45px}.panel-pad{padding:30px}.explanation{font-size:17px}.state-pair{grid-template-columns:1fr 1fr}.trace-note{margin-top:25px}}
@media(max-width:1150px){.layout{grid-template-columns:210px minmax(0,1fr)}main{padding:24px}.sidebar{padding:22px 10px}.learning-grid,.practice-grid{grid-template-columns:1fr}.explanation{max-width:800px}.practice-grid{gap:18px}.topbar{padding:0 18px}.trace-note{min-height:0}.state-pair{grid-template-columns:1fr 1fr}.practice-grid>.panel:first-child{order:0}}
@media(max-width:760px){.topbar{height:auto;min-height:68px;flex-wrap:wrap;padding:13px 15px;gap:10px}.brand small{display:none}.topnav{gap:4px}.topnav a{font-size:11px;padding:6px 7px}.brand strong{font-size:9px}.brandmark{width:30px;height:30px}.layout{display:block}.sidebar{display:none}.mobile-lessons{display:block;margin-bottom:20px}.mobile-lessons label{font-size:11px;color:var(--faint);display:block;margin-bottom:5px}.mobile-lessons select{width:100%;color:var(--ink);background:var(--surface);padding:10px;border:1px solid var(--line);border-radius:8px}main{padding:20px 15px 35px}.lesson-meta{display:none}.lesson-head{margin:17px 0}.stages{gap:1px}.stages button{font-size:11px;display:flex;flex-direction:column;gap:7px;padding:10px 1px}.panel-pad{padding:21px}.explanation{font-size:15px}.state-pair{grid-template-columns:1fr}.trace{padding:20px}.course-main{padding:28px 16px 45px}.course-intro{grid-template-columns:1fr;gap:10px}.course-visual{display:none}.part-one,.chapter-grid{grid-template-columns:1fr}.part-one{padding:23px;gap:20px}.chapter:last-child ul{display:block}.chapter:last-child li+li{border-top:1px solid var(--line)}.chapter:last-child{grid-column:auto}.course-start .button{flex:1}.question{font-size:19px}.action-row{align-items:flex-start}.editor-footer span{width:100%;margin:0}.code{padding:18px}pre{font-size:12px}textarea{font-size:13px;min-height:340px}.breadcrumb{font-size:10px}}
@media(prefers-reduced-motion:no-preference){.panel{animation:enter .2s ease}@keyframes enter{from{opacity:.5;transform:translateY(3px)}to{opacity:1;transform:translateY(0)}}}

/* Course-wide navigation, including Part III. */
.topbar{height:auto;min-height:72px;flex-wrap:wrap;padding-top:12px;padding-bottom:12px}.topnav{flex-wrap:wrap}
@media(max-width:1100px){.topbar{position:relative}.sidebar{top:0;height:100vh}}
@media(max-width:760px){.topnav{justify-content:flex-start}}