:root{--nav-height:42px;--ink:#1c2435;--muted:#667085;--primary:#5b51cf;--primary-dark:#4036aa;--primary-soft:#eeecff;--aqua:#21aeba;--aqua-soft:#e9fbfc;--warning:#e9a62c;--line:#e5e8f0;--paper:#fff;--canvas:#f5f7fb;--code:#0c1220;--radius:12px}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{width:100%;max-width:100vw;margin:0;overflow:hidden;background:var(--canvas);color:var(--ink);font-family:"Nunito Sans","Segoe UI",sans-serif;font-size:14px;line-height:1.65}
a,button{font:inherit}
a:focus-visible,button:focus-visible,[tabindex="0"]:focus-visible{outline:3px solid #f8bd4a;outline-offset:2px}
.visually-hidden{position:absolute!important;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.skip-link{position:fixed;z-index:2000;top:6px;left:8px;transform:translateY(-150%);padding:7px 11px;border-radius:7px;background:#fff;color:var(--primary-dark);font-weight:800;text-decoration:none}
.skip-link:focus{transform:none}
.page-progress{position:fixed;z-index:1500;inset:0 auto auto 0;width:0;height:3px;background:linear-gradient(90deg,#ff8f70,#f4c84a,#34d0b3);box-shadow:0 0 10px #34d0b3;transition:width .08s linear}
.site-navbar{position:relative;z-index:1000;height:var(--nav-height);display:flex;align-items:center;justify-content:space-between;padding:0 12px;background:linear-gradient(110deg,#5147c6 0%,#6e65df 57%,#269dbb 100%);box-shadow:0 2px 6px rgba(20,17,64,.25)}
.brand{display:inline-flex;min-width:0;align-items:center;gap:7px;color:#fff;text-decoration:none}
.brand img{width:24px;height:24px;border-radius:7px;box-shadow:0 3px 9px #24206542}
.brand-copy{line-height:1.05}.brand-copy strong{display:block;font-size:13px;letter-spacing:.2px}.brand-copy small{display:block;margin-top:2px;color:#e9f9ff;font-size:8px;font-weight:700;letter-spacing:.35px;text-transform:uppercase}
.mobile-panel-button{display:none;align-items:center;gap:5px;min-height:27px;padding:4px 7px;border:1px solid rgba(255,255,255,.42);border-radius:7px;background:rgba(255,255,255,.13);color:#fff;font-size:10px;font-weight:800;cursor:pointer}
.course-layout{display:grid;grid-template-columns:minmax(215px,16.5vw) minmax(0,1fr) minmax(205px,16vw);gap:4px;width:100%;min-width:0;height:calc(100vh - var(--nav-height));max-width:1920px;margin:0 auto}
.course-sidebar,.page-rail,.main-column{min-height:0;background:var(--paper)}
.course-sidebar,.page-rail{height:100%;overflow-y:auto;scrollbar-width:thin;scrollbar-color:#8a81e8 transparent}
.course-sidebar::-webkit-scrollbar,.page-rail::-webkit-scrollbar,.toc-links::-webkit-scrollbar,.quick-links::-webkit-scrollbar,.main-column::-webkit-scrollbar,.table-scroll::-webkit-scrollbar,.code-block pre::-webkit-scrollbar{width:3px;height:3px}
.course-sidebar::-webkit-scrollbar-thumb,.page-rail::-webkit-scrollbar-thumb,.toc-links::-webkit-scrollbar-thumb,.quick-links::-webkit-scrollbar-thumb,.main-column::-webkit-scrollbar-thumb,.table-scroll::-webkit-scrollbar-thumb,.code-block pre::-webkit-scrollbar-thumb{border-radius:10px;background:linear-gradient(135deg,#8379e6,#28b3bf)}
.sidebar-header{padding:15px 13px 12px;border-bottom:1px solid var(--line);background:linear-gradient(145deg,#f0efff,#ebfbfc)}
.sidebar-kicker{display:block;color:var(--primary);font-size:9px;font-weight:900;letter-spacing:1.2px;text-transform:uppercase}
.sidebar-header h2{margin:3px 0 0;font-family:"Lora",Georgia,serif;font-size:17px;line-height:1.25}
.chapter-navigation{padding:9px}.chapter-group{margin-bottom:8px}.chapter-disclosure{min-width:0}.chapter-disclosure>summary{display:flex;align-items:center;list-style:none;cursor:pointer;user-select:none}.chapter-disclosure>summary::-webkit-details-marker{display:none}
.chapter-disclosure{position:relative;overflow:hidden;border:1px solid #dddff0;border-radius:11px;background:#fff;box-shadow:0 5px 15px rgba(51,47,108,.06)}.chapter-disclosure::before{content:"";position:absolute;z-index:0;inset:0 0 auto;height:2px;background:linear-gradient(90deg,var(--primary),#8a7cf0,var(--aqua))}.chapter-disclosure>summary{position:relative;z-index:1;gap:8px;min-height:48px;padding:8px;background:linear-gradient(120deg,#faf9ff,#f1fbfc);transition:background .2s}.chapter-disclosure>summary:hover{background:linear-gradient(120deg,#f0eeff,#e9fafa)}
.chapter-number{display:grid;flex:0 0 29px;place-items:center;width:29px;height:29px;border-radius:9px;background:linear-gradient(145deg,var(--primary),#7770e8);box-shadow:0 5px 11px rgba(91,81,207,.24);color:#fff;font:900 9px/1 "JetBrains Mono",Consolas,monospace}.chapter-summary-copy{min-width:0;flex:1}.chapter-summary-copy strong{display:block;overflow:hidden;color:#313a52;font-size:10.5px;line-height:1.25;text-overflow:ellipsis}.chapter-summary-copy small{display:block;margin:0 0 2px;color:var(--primary);font-size:8px;font-weight:800;letter-spacing:.35px;text-transform:uppercase}.disclosure-chevron{flex:0 0 7px;width:7px;height:7px;margin-right:3px;border-right:1.5px solid #69738a;border-bottom:1.5px solid #69738a;transform:rotate(45deg);transition:transform .22s ease}.chapter-disclosure[open]>summary .disclosure-chevron{transform:rotate(225deg)}
.chapter-drawer{position:relative;padding:7px;background:linear-gradient(#fff,#fbfbfe);animation:drawer-reveal .2s ease}.chapter-drawer::before{content:"";position:absolute;top:0;bottom:11px;left:20px;width:1px;background:linear-gradient(var(--aqua),#d8dcf0 65%,transparent)}
.topic-link{position:relative;display:flex;align-items:center;gap:8px;margin:2px 0 2px 17px;padding:7px 8px;border:1px solid transparent;border-radius:9px;color:#3c4457;font-size:10px;font-weight:700;line-height:1.3;text-decoration:none;transition:background .15s,border-color .15s,color .15s,transform .15s}.topic-index{display:grid;flex:0 0 21px;place-items:center;width:21px;height:21px;border-radius:7px;background:#f0eff8;color:#8179ad;font:800 8.5px/1 "JetBrains Mono",Consolas,monospace}.topic-link-title{min-width:0;overflow:hidden;text-overflow:ellipsis}.topic-link:hover{transform:translateX(2px);border-color:#e3e0f7;background:var(--primary-soft)}.topic-link.is-active{border-color:transparent;background:linear-gradient(90deg,var(--primary),#7067df);color:#fff;box-shadow:0 4px 10px rgba(91,81,207,.18)}.topic-link.is-active .topic-index{background:rgba(255,255,255,.22);color:#fff}
@keyframes drawer-reveal{from{opacity:0;transform:translateY(-4px)}to{opacity:1;transform:none}}
.main-column{width:100%;min-width:0;height:100%;overflow-y:auto;overflow-x:hidden;scrollbar-width:thin;scrollbar-color:#aaa4e8 transparent}
.topic-header{position:sticky;z-index:30;top:0;padding:8px 24px 9px;border-bottom:1px solid var(--line);background:rgba(255,255,255,.95);box-shadow:0 4px 14px rgba(41,45,75,.05);backdrop-filter:blur(10px)}
.breadcrumbs{display:flex;align-items:center;gap:5px;overflow:hidden;margin-bottom:2px;color:#7a8498;font-size:9px;white-space:nowrap}.breadcrumbs a{color:var(--primary);text-decoration:none}.breadcrumbs span:last-child{overflow:hidden;text-overflow:ellipsis}.breadcrumbs i{font-style:normal;color:#a4aaba}
.title-line{display:flex;align-items:flex-end;justify-content:space-between;gap:14px}.title-line h1{margin:0;font-family:"Lora",Georgia,serif;font-size:clamp(22px,2.2vw,34px);line-height:1.15;color:#20283a}.reading-time{flex:0 0 auto;margin-bottom:2px;padding:3px 7px;border:1px solid #dcd9fa;border-radius:999px;background:var(--primary-soft);color:var(--primary-dark);font-size:9px;font-weight:800}.topic-subtitle{margin:2px 0 0;color:var(--muted);font-size:11px;line-height:1.35}
.lesson-content{width:min(100%,980px);min-width:0;margin:0 auto;padding:14px 28px 34px}.lesson-content h2,.lesson-content h3,.lesson-content h4{scroll-margin-top:105px}.lesson-content h2{position:relative;margin:34px 0 11px;padding:9px 13px;border-left:4px solid var(--primary);border-radius:7px 10px 10px 7px;background:linear-gradient(90deg,var(--primary-soft),#f4fbff 78%,transparent);font-family:"Lora",Georgia,serif;font-size:21px;line-height:1.3;color:#292555}.lesson-content h2:not(:first-child)::before{content:"";position:absolute;top:-19px;left:0;width:100%;height:1px;background:linear-gradient(90deg,var(--line),transparent)}
.lesson-content h2.sensitive-heading{border-left-color:var(--warning);background:linear-gradient(90deg,#fff4da,#fffaf0 75%,transparent);color:#503b11}.lesson-content h3{display:table;margin:20px 0 7px;padding:4px 9px;border-radius:6px;background:var(--aqua-soft);color:#166d78;font-size:15px;line-height:1.35}.lesson-content h3.sensitive-heading{background:#fff0e8;color:#9b4625}.lesson-content h4{margin:16px 0 6px;color:var(--primary-dark);font-size:13px}.lesson-content p{margin:7px 0;color:#313b4f}.lesson-content ul,.lesson-content ol{margin:7px 0 10px;padding-left:25px}.lesson-content li{margin:3px 0}.lesson-content li::marker{color:var(--primary);font-weight:800}.lesson-content strong{color:#222b3e}.lesson-content code:not(pre code){padding:1px 5px;border:1px solid #e2dff5;border-radius:5px;background:#f0effb;color:#9f2367;font-family:"JetBrains Mono",Consolas,monospace;font-size:.86em;white-space:nowrap}.lesson-content blockquote{margin:9px 0;padding:9px 13px;border-left:4px solid #e8b641;border-radius:4px 8px 8px 4px;background:#fff8e5;color:#544727}.lesson-content blockquote p{margin:0;color:inherit}
.code-block{position:relative;isolation:isolate;width:100%;min-width:0;max-width:100%;margin:7px 0 10px;overflow:hidden;border:1px solid #334e7d;border-radius:10px;background:linear-gradient(145deg,#070b14 0%,#0b1220 100%);box-shadow:0 10px 28px rgba(2,6,23,.28),inset 0 1px 0 rgba(125,211,252,.14);transition:border-color .18s ease,box-shadow .18s ease,transform .18s ease}.code-block::before{content:"";position:absolute;z-index:3;top:0;right:9%;left:9%;height:1px;background:linear-gradient(90deg,transparent,rgba(125,211,252,.9),rgba(244,114,182,.75),transparent);pointer-events:none}.code-block.is-copied{border-color:#22d3ee;box-shadow:0 0 0 3px rgba(34,211,238,.24),0 10px 24px rgba(8,145,178,.24);transform:translateY(-1px)}.code-toolbar{position:relative;z-index:2;display:flex;align-items:center;justify-content:space-between;min-width:0;min-height:34px;padding:4px 6px 4px 10px;border-bottom:1px solid #334e7d;background:linear-gradient(90deg,#101827 0%,#172554 58%,#1e1b4b 100%);box-shadow:inset 0 -1px 0 rgba(125,211,252,.08);color:#e2e8f0}.code-language{display:inline-flex;align-items:center;gap:6px;color:#bae6fd;font-family:"Cascadia Code","JetBrains Mono","Fira Code",Consolas,monospace;font-size:.66rem;font-weight:850;letter-spacing:.08em;text-transform:uppercase}.code-language::before{content:"";width:7px;height:7px;border-radius:50%;background:#38bdf8;box-shadow:0 0 9px rgba(56,189,248,.85)}.code-controls{display:flex;flex:0 0 auto;gap:5px}.code-button{min-height:25px;padding:3px 7px;border:1px solid #64748b;border-radius:6px;background:linear-gradient(180deg,#334155,#1e293b);color:#f8fafc;font-size:.62rem;font-weight:800;cursor:pointer}.code-button:hover{border-color:#38bdf8;color:#fff;background:#075985}.code-button.is-success{border-color:#86efac;color:#052e16;background:#86efac}.code-block pre{position:relative;width:100%;min-width:0;max-width:100%;margin:0;overflow:auto;padding:12px 13px;background-color:#070b14;background-image:radial-gradient(circle at 88% 0%,rgba(37,99,235,.12),transparent 34%),linear-gradient(145deg,#070b14 0%,#0b1220 100%);color:#f8fafc;tab-size:4;-webkit-overflow-scrolling:touch;scrollbar-width:thin;scrollbar-color:#38bdf8 transparent}.code-block pre:focus-visible{outline:3px solid #38bdf8;outline-offset:-3px}.code-block code{display:block;width:max-content;min-width:100%;color:#f8fafc;font-family:"Cascadia Code","JetBrains Mono","Fira Code","SFMono-Regular",Menlo,Consolas,monospace;font-size:clamp(.95rem,1.1vw,1.08rem);font-weight:500;line-height:1.68;letter-spacing:.008em;white-space:pre;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;font-optical-sizing:auto;font-variant-ligatures:none;font-feature-settings:"calt" 0,"liga" 0}.code-block code::selection,.code-block code *::selection{color:#111827;background:#fbbf24}.token-comment{color:#a8b3c7;font-style:italic}.token-string{color:#86efac}.token-keyword{color:#f472b6;font-weight:800}.token-number{color:#fde047}.token-annotation{color:#67e8f9;font-weight:700}.token-type{color:#60a5fa;font-weight:700}.token-method{color:#fbbf24}.token-literal{color:#c4b5fd;font-weight:700}.token-operator{color:#fb7185;font-weight:650}.code-block:fullscreen{display:flex;flex-direction:column;border:0;border-radius:0}.code-block:fullscreen pre{flex:1}.code-block:fullscreen code{font-size:clamp(1rem,1.35vw,1.2rem)}
.table-scroll{max-width:100%;margin:11px 0;overflow:auto;border:1px solid var(--line);border-radius:8px;scrollbar-width:thin;scrollbar-color:#8a81e8 transparent}table{width:100%;border-collapse:collapse;font-size:11px}th,td{padding:7px 9px;border-right:1px solid var(--line);border-bottom:1px solid var(--line);text-align:left;vertical-align:top}th{background:#554bc9;color:#fff;font-weight:800}tbody tr:nth-child(even){background:#f8f8fd}tr:last-child td{border-bottom:0}th:last-child,td:last-child{border-right:0}
.lesson-pager{display:flex;justify-content:space-between;gap:8px;width:min(calc(100% - 56px),980px);margin:0 auto 22px;padding-top:13px;border-top:1px solid var(--line)}.pager-button{display:inline-flex;align-items:center;min-height:29px;padding:4px 9px;border-radius:7px;background:var(--primary);color:#fff;font-size:10px;font-weight:800;text-decoration:none}.pager-button.is-disabled{border:1px solid var(--line);background:#f4f5f8;color:#98a1b2;cursor:not-allowed}
.lesson-pager-top{justify-content:space-between;width:100%;margin:8px 0 0;padding-top:0;border-top:0;gap:8px}.lesson-pager-top .pager-button{min-height:23px;padding:3px 8px;font-size:9px}
.page-rail{padding:9px;background:#f8f9fd}.rail-card{margin-bottom:7px;padding:10px;border:1px solid var(--line);border-radius:10px;background:#fff;box-shadow:0 3px 12px rgba(44,49,89,.04)}.rail-card h2{margin:0 0 7px;font-size:11px;line-height:1.3}.reading-track{height:5px;overflow:hidden;border-radius:10px;background:#eaecf2}.reading-track span{display:block;width:0;height:100%;border-radius:inherit;background:linear-gradient(90deg,var(--primary),var(--aqua));transition:width .08s linear}.reading-meta{display:flex;justify-content:space-between;margin-top:5px;color:var(--muted);font-size:9px}.reading-meta strong{color:var(--primary-dark)}.toc-links{max-height:47vh;overflow-y:auto;scrollbar-width:thin}.toc-links a{display:block;padding:4px 5px;border-left:2px solid #e3e5ed;color:#687286;font-size:9.5px;line-height:1.3;text-decoration:none;transition:.15s}.toc-links a.toc-subtopic{padding-left:13px}.toc-links a:hover,.toc-links a.is-active{border-left-color:var(--primary);background:var(--primary-soft);color:var(--primary-dark)}.toc-links a.is-active{font-weight:900}.quick-links{display:grid;grid-template-columns:1fr 1fr;gap:4px;max-height:25vh;overflow-y:auto;scrollbar-width:thin}.quick-links a{padding:6px;border-radius:6px;background:#f2f4f8;color:#445069;font-size:8.8px;font-weight:700;line-height:1.25;text-decoration:none}.quick-links a:hover{background:var(--aqua-soft);color:#176d77}
.course-footer{padding:20px 24px 13px;background:#141d2e;color:#aeb9ca}.footer-grid{display:grid;grid-template-columns:1.4fr repeat(4,1fr);gap:17px;max-width:1120px;margin:0 auto}.footer-brand{display:inline-flex;align-items:center;gap:8px;margin-bottom:6px;color:#fff;text-decoration:none}.footer-brand img{width:28px;height:28px;border-radius:7px}.footer-brand strong{display:block;font-size:12px}.footer-brand small{display:block;color:#8fa1b9;font-size:8px;text-transform:uppercase}.footer-description{max-width:270px;margin:0;font-size:9.5px;line-height:1.55}.footer-column h2{margin:0 0 6px;color:#fff;font-size:10px}.footer-column a{display:block;width:fit-content;margin:3px 0;color:#aeb9ca;font-size:9px;text-decoration:none}.footer-column a:hover{color:#65dfd1;text-decoration:underline}.footer-bottom{max-width:1120px;margin:12px auto 0;padding-top:9px;border-top:1px solid rgba(255,255,255,.1);font-size:8.5px;text-align:center}
.panel-overlay{display:none}
@media(max-width:1024px){.course-layout{grid-template-columns:1fr}.mobile-panel-button{display:inline-flex}.course-sidebar,.page-rail{position:fixed;z-index:950;top:var(--nav-height);bottom:0;width:min(290px,86vw);height:auto;transition:transform .24s ease;box-shadow:8px 0 28px rgba(17,24,39,.24)}.course-sidebar{left:0;transform:translateX(-105%)}.page-rail{right:0;transform:translateX(105%);box-shadow:-8px 0 28px rgba(17,24,39,.24)}body.left-panel-open .course-sidebar,body.right-panel-open .page-rail{transform:none}.panel-overlay{position:fixed;z-index:900;inset:var(--nav-height) 0 0;background:rgba(17,24,39,.5)}body.left-panel-open .panel-overlay,body.right-panel-open .panel-overlay{display:block}.main-column{grid-column:1}.topic-header{padding-inline:16px}.lesson-content{padding-inline:18px}.lesson-pager{width:calc(100% - 36px)}.footer-grid{grid-template-columns:1.3fr repeat(2,1fr)}.brand-copy small{display:none}}
@media(max-width:620px){.site-navbar{padding-inline:8px}.mobile-panel-button{position:relative;z-index:2;flex:0 0 auto;font-size:9px}.brand{position:absolute;left:50%;transform:translateX(-50%)}.brand-copy strong{font-size:13px}.topic-header{padding:7px 11px}.title-line{align-items:flex-start}.reading-time{display:none}.topic-subtitle{font-size:10px}.lesson-content{padding:10px 11px 26px}.lesson-content p,.lesson-content li{overflow-wrap:anywhere}.lesson-content h2{margin-top:28px;padding:8px 10px;font-size:18px}.lesson-content h3{font-size:14px}.lesson-content p,.lesson-content li{font-size:13px}.code-block pre{padding:12px 10px}.code-button{padding-inline:5px}.lesson-pager{width:calc(100% - 22px)}.lesson-pager-top{flex-wrap:wrap}.course-footer{padding-inline:14px}.footer-grid{grid-template-columns:1fr 1fr;gap:14px}.footer-brand-column{grid-column:1/-1}.quick-links{max-height:34vh}}
@media(max-width:380px){.mobile-panel-button .button-text{display:none}.mobile-panel-button{padding-inline:9px}.footer-grid{grid-template-columns:1fr}.footer-brand-column{grid-column:auto}.title-line h1{font-size:20px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{scroll-behavior:auto!important;transition-duration:.01ms!important}}
.code-block.is-fullscreen-fallback{position:fixed;z-index:2100;inset:0;display:flex;flex-direction:column;width:auto;max-width:none;height:100dvh;margin:0;border:0;border-radius:0;background:#070b14}.code-block.is-fullscreen-fallback .code-toolbar{flex:0 0 auto}.code-block.is-fullscreen-fallback pre{flex:1;min-height:0}.code-block.is-fullscreen-fallback code{font-size:clamp(1rem,1.35vw,1.2rem)}
.code-block code,.code-block:fullscreen code,.code-block.is-fullscreen-fallback code{font-size:.8125rem;line-height:1.58}
.sidebar-header h2,.title-line h1,.lesson-content h2,.lesson-content h3,.lesson-content h4,.rail-card h2,.footer-column h2{font-family:"Nunito Sans","Segoe UI",sans-serif}