:root{color-scheme:dark;--bg:#0b1521;--surface:#111f2f;--line:#26384a;--text:#f1f5f7;--muted:#a6b7c6;--accent:#7be2ca;--amber:#ecc58a;font-family:Inter,Segoe UI,Arial,sans-serif;font-size:16px}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text)}a{color:inherit;text-decoration:none}button,input{font:inherit}a,button,input{ -webkit-tap-highlight-color:transparent}a:focus-visible,button:focus-visible,input:focus-visible{outline:2px solid var(--accent);outline-offset:4px}.skip{position:absolute;left:16px;top:-70px;z-index:10;padding:14px;background:var(--accent);color:var(--bg)}.skip:focus{top:10px}header{height:86px;display:flex;align-items:center;justify-content:space-between;padding:0 38px;border-bottom:1px solid var(--line);gap:24px}.brand{display:flex;align-items:center;gap:10px;font-size:25px;font-weight:700;letter-spacing:-.6px}.brand-mark{display:grid;place-items:center;width:34px;height:34px;background:var(--accent);color:var(--bg);border-radius:9px;font-size:30px}.brand-separator{margin:0 8px;color:#4a6072;font-weight:400}.brand-course{font-size:17px;letter-spacing:1px}.header-note{font-size:12px;letter-spacing:2px;color:var(--muted)}.edition{font-size:14px;color:var(--muted)}.edition span{padding:0 9px;color:var(--accent)}.workspace{display:grid;grid-template-columns:325px minmax(0,1fr);max-width:1800px;margin:auto}aside{border-right:1px solid var(--line);padding:30px 20px;position:sticky;top:0;height:calc(100vh - 0px);display:flex;flex-direction:column;min-height:400px}.sidebar-heading{display:flex;align-items:center;justify-content:space-between;margin:0 8px 26px}.eyebrow{font-size:12px;letter-spacing:1.8px;font-weight:600;color:var(--accent);margin:0 0 12px}h2{font-size:21px;letter-spacing:-.5px;margin:9px 0 0;font-weight:600}.count{font-size:13px;border:1px solid var(--line);border-radius:6px;padding:6px 8px;color:var(--muted)}.search-label{font-size:14px;margin:0 8px 10px;color:var(--muted)}input{width:100%;padding:13px 12px;border:1px solid #345066;border-radius:7px;background:#0c1825;color:var(--text);font-size:14px}input::placeholder{color:#8198ab}.muted{color:var(--muted);font-size:12px;margin:15px 8px}nav{overflow:auto;scrollbar-width:thin;scrollbar-color:#345066 transparent;flex:1;padding-right:4px}.chapter-link{display:grid;grid-template-columns:32px minmax(0,1fr);gap:9px;padding:13px 10px;border-radius:7px;border:1px solid transparent;margin:3px 0}.chapter-link:hover{background:#152738}.chapter-link[aria-current=page]{background:#18342f;border-color:#3b7668}.chapter-number{font-size:13px;color:#8ea8bd;font-variant-numeric:tabular-nums;padding-top:2px}.chapter-link[aria-current=page] .chapter-number{color:var(--accent)}.chapter-title{font-size:14px;line-height:1.5;display:block}.chapter-time{display:block;color:#8ba0b3;font-size:12px;margin-top:4px}main{min-width:0;padding:35px clamp(24px,4vw,68px) 0}.lesson-heading{display:flex;justify-content:space-between;gap:24px;align-items:center;margin-bottom:25px}h1{font-size:clamp(28px,2.8vw,42px);letter-spacing:-1.2px;line-height:1.15;margin:0;font-weight:600}.lesson-label{font-size:11px;letter-spacing:1.5px;color:var(--muted);white-space:nowrap}.player-shell{aspect-ratio:16/9;background:#07101a;border:1px solid #2f4557;border-radius:12px;overflow:hidden;position:relative}.player-intro{position:absolute;inset:0;display:flex;flex-direction:column;justify-content:center;align-items:center;background:radial-gradient(ellipse at 70% 0%,#25434c 0%,#111e30 50%,#08121d 100%);padding:30px;text-align:center}.player-intro h2{font-size:clamp(22px,3vw,40px);max-width:650px;margin:12px 0 28px}.play-button{background:var(--accent);color:#092a27;border:0;border-radius:7px;padding:14px 25px;font-weight:600;cursor:pointer}.play-button:hover{background:#a3f5df}.play-icon{font-size:46px;color:var(--accent)}iframe{border:0;width:100%;height:100%;background:#fff}.player-footer{display:flex;justify-content:space-between;gap:15px;color:var(--muted);font-size:13px;margin-top:14px;line-height:1.5}.player-footer a{color:var(--accent);text-decoration:underline;text-underline-offset:4px}.materials-heading{margin:36px 0 18px}.materials-heading .eyebrow{font-size:11px;color:var(--muted)}.materials{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.material{border:1px solid var(--line);border-radius:9px;background:var(--surface);padding:20px;display:block;transition:border-color .15s,background .15s}.material:hover{border-color:#628c8c;background:#182c3c}.material-top{display:flex;justify-content:space-between;color:var(--accent);font-size:12px;letter-spacing:1px;margin-bottom:20px}.material h3{font-size:17px;font-weight:600;margin:0 0 7px}.material p{color:var(--muted);font-size:13px;line-height:1.5;margin:0}.outline{border-top:1px solid var(--line);margin-top:38px;padding-top:28px;display:grid;grid-template-columns:220px minmax(0,1fr);gap:25px}.outline .eyebrow{font-size:11px;color:var(--muted)}ol{padding:0;margin:0;list-style:none;counter-reset:lesson}li{counter-increment:lesson;padding:12px 0 12px 32px;border-bottom:1px solid #1c2e3e;position:relative;font-size:15px;line-height:1.5}li:before{content:counter(lesson,decimal-leading-zero);position:absolute;left:0;color:#6d8a9e;font-size:12px;top:15px}li small{display:block;color:var(--muted);font-size:13px;margin-top:4px}.chapter-pagination{display:flex;justify-content:space-between;gap:20px;margin:35px 0}.chapter-step{max-width:48%;font-size:15px;line-height:1.5}.chapter-step span{display:block;color:var(--accent);font-size:12px;letter-spacing:1px;margin-bottom:8px}.next{text-align:right;margin-left:auto}footer{border-top:1px solid var(--line);padding:25px 0;color:#98afbf;font-size:13px;display:flex;justify-content:space-between;gap:20px}.noscript{padding:30px}.empty{padding:24px 12px;color:var(--muted)}@media(min-width:1600px){main{padding-top:45px}}@media(max-width:1100px){.header-note,.lesson-label{display:none}.workspace{grid-template-columns:280px minmax(0,1fr)}.materials{grid-template-columns:repeat(2,minmax(0,1fr))}.outline{display:block}.outline ol{margin-top:20px}}@media(max-width:760px){header{height:70px;padding:0 20px}.brand{font-size:22px}.edition{font-size:12px}.brand-separator{margin:0 3px}.workspace{display:flex;flex-direction:column}aside{position:relative;height:auto;min-height:0;border-right:0;border-bottom:1px solid var(--line);padding:20px}nav{max-height:210px}.sidebar-heading{margin-bottom:16px}.sidebar-heading .eyebrow{display:none}main{padding:26px 20px 0}h1{font-size:30px}.lesson-heading{margin-bottom:20px}.player-footer{font-size:12px;flex-wrap:wrap}.materials{gap:10px}.material{padding:16px}.material h3{font-size:16px}.player-intro{padding:18px}.player-intro h2{font-size:23px;margin-bottom:20px}.player-intro .eyebrow{font-size:10px}footer{display:block;line-height:1.7}footer span{display:block}}@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}

.viewer-tabs{display:flex;gap:6px;margin:0 0 14px;flex-wrap:wrap}.viewer-tabs button{border:1px solid transparent;color:var(--muted);background:transparent;padding:10px 14px;font-size:14px;border-radius:6px;cursor:pointer}.viewer-tabs button[aria-pressed=true]{color:var(--accent);background:#18342f;border-color:#3b7668}.viewer-tabs button:hover{color:var(--text)}.player-shell.document-view{aspect-ratio:auto;height:75vh;min-height:400px}.chapter-step[hidden]{display:none}