@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@500;600;700&family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500;600&display=swap');

/* =============================================================
   ap0t · LMS — shared shell styles
   Dark editorial design system ("rust blog" style):
   · Near-black backgrounds, orange rust accent, strong display type
   · Space Grotesk for headings/UI · Inter for body · JetBrains Mono for code
   ============================================================= */

:root{
  --bg: #08090D;
  --bg-soft: #11131A;
  --card: #151820;
  --card-2: #1B1F2A;
  --border: #272C3A;
  --text: #F3F4F6;
  --muted: #9CA3AF;
  --accent: #FF6B2C;
  --accent-2: #FFB03A;
  --good: #3DD68C;
  --warn: #FFB03A;
  --danger: #FF6369;
  --hindi: #FFB03A;
  --tech: #FF8C5A;
  --tag: #1C202B;
  --on-accent: #160B04;
  --code-bg: #0C0E14;
  --code-text: #E9E6E1;
  --glow-calm: rgba(255, 107, 44, 0.13);
  --glow-warm: rgba(255, 176, 58, 0.10);
  --glow-good: rgba(61, 214, 140, 0.08);
  --shadow: 0 14px 44px rgba(0, 0, 0, 0.45);
  --radius: 14px;
}
[data-theme="light"]{
  --bg: #f6f5f2;
  --bg-soft: #fbfaf7;
  --card: #ffffff;
  --card-2: #f7f4ee;
  --border: #e2ddd2;
  --text: #1c1917;
  --muted: #6b6560;
  --accent: #E8590C;
  --accent-2: #F08C00;
  --good: #2f9e6e;
  --warn: #d9890c;
  --danger: #c92a2a;
  --hindi: #a67c00;
  --tech: #e8590c;
  --tag: #efece5;
  --on-accent: #ffffff;
  --code-bg: #22272f;
  --code-text: #ece8e3;
  --glow-calm: rgba(232, 89, 12, 0.09);
  --glow-warm: rgba(240, 140, 0, 0.08);
  --glow-good: rgba(47, 158, 110, 0.07);
  --shadow: 0 10px 30px rgba(60, 50, 40, 0.08);
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  font-family: "Inter", ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color:var(--text);
  background:
    radial-gradient(1200px 700px at 85% -10%, var(--glow-calm), transparent 58%),
    radial-gradient(900px 500px at -5% 15%, var(--glow-warm), transparent 55%),
    radial-gradient(600px 400px at 50% 100%, var(--glow-good), transparent 50%),
    var(--bg);
  font-size:15.5px;
  line-height:1.7;
  letter-spacing:.012em;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
a{color:var(--accent-2); text-decoration:none}
a:hover{text-decoration:underline}

/* Display type — Space Grotesk for headings and nav chrome */
h1,h2,h3,h4,h5,h6,
.hero h2,.section-head h3,.brand-link h1,.grp-label,.nav-course,.nav-home,
details.q summary,.btn,.pill,.eyebrow,.cc-tag,.badge{
  font-family:"Space Grotesk","Inter",ui-sans-serif,system-ui,sans-serif;
}
h1,h2,h3{letter-spacing:-.01em}

/* Anchor offset for sticky toolbar */
[id]{scroll-margin-top:80px}

/* Layout */
.shell{display:grid; grid-template-columns: 300px 1fr; min-height:100vh}
.sidebar{
  position:sticky; top:0; align-self:start; height:100vh; overflow:auto;
  padding:24px 18px; border-right:1px solid var(--border);
  background: linear-gradient(180deg, var(--bg-soft), transparent);
  backdrop-filter: blur(8px);
  z-index:20;
}
.brand-link{display:flex; align-items:center; gap:10px; margin-bottom:16px; color:var(--text); text-decoration:none}
.brand-link:hover{text-decoration:none; opacity:.9}
.logo{
  width:38px;height:38px;border-radius:10px;
  background: conic-gradient(from 200deg, var(--accent), var(--accent-2), var(--accent));
  box-shadow: 0 6px 20px rgba(255, 107, 44, 0.35);
  display:grid;place-items:center;color:var(--on-accent);font-weight:900;
}
.brand-link h1{font-size:16px; margin:0; letter-spacing:.2px}
.brand-link p{margin:0; font-size:12px; color:var(--muted)}

/* Global sidebar search */
.sidebar-search-wrap{
  position:relative; margin-bottom:12px; z-index:25;
}
.sidebar-search{
  display:flex; align-items:center; gap:8px;
  padding:8px 10px; border-radius:10px;
  border:1px solid var(--border); background:var(--card);
  cursor:text; transition:border-color .15s, box-shadow .15s;
}
.sidebar-search:focus-within{
  border-color:var(--accent);
  box-shadow:0 0 0 3px var(--glow-calm);
}
.sidebar-search .ico-svg{width:16px; height:16px; color:var(--muted); flex-shrink:0}
.sidebar-search input{
  flex:1; min-width:0; border:none; outline:none;
  background:transparent; color:var(--text); font-size:13px;
  font-family:inherit;
}
.sidebar-search input::placeholder{color:var(--muted)}
.search-hint{
  font-size:10px; font-family:ui-monospace,Menlo,monospace;
  padding:2px 6px; border-radius:5px;
  border:1px solid var(--border); background:var(--bg-soft);
  color:var(--muted); flex-shrink:0;
}
.sidebar-search-results{
  position:absolute; left:0; right:0; top:calc(100% + 6px);
  max-height:min(60vh, 420px); overflow:auto;
  border:1px solid var(--border); border-radius:12px;
  background:var(--card); box-shadow:var(--shadow);
  padding:6px;
}
.search-hit{
  display:flex; align-items:center; gap:10px;
  padding:8px 10px; border-radius:8px;
  color:var(--text); text-decoration:none;
  transition:background .12s;
}
.search-hit:hover{background:var(--bg-soft); text-decoration:none}
.search-hit-icon{color:var(--accent-2); display:flex}
.search-hit-body{flex:1; min-width:0; display:flex; flex-direction:column; gap:2px}
.search-hit-title{font-size:13px; font-weight:600; white-space:nowrap; overflow:hidden; text-overflow:ellipsis}
.search-hit-sub{font-size:11px; color:var(--muted); white-space:nowrap; overflow:hidden; text-overflow:ellipsis}
.search-hit-type{
  font-size:9px; font-weight:800; text-transform:uppercase;
  letter-spacing:.06em; color:var(--muted);
  padding:2px 6px; border-radius:4px; background:var(--tag);
}
.search-empty{padding:12px; font-size:12px; color:var(--muted); text-align:center}

/* SVG icons in nav */
.ico-svg{width:16px; height:16px; flex-shrink:0; display:block}
.ico-svg.ico-sm{width:12px; height:12px}

/* Sidebar nav — aligned grid rows */
.nav{
  display:flex; flex-direction:column; gap:2px; margin-top:6px;
  --nav-num: 26px;
  --nav-ico: 24px;
  --nav-gap: 8px;
}

.nav a, .nav .nav-home, .nav .nav-course{
  color:var(--text);
  min-height:36px;
  padding:6px 10px;
  border-radius:8px;
  font-size:13.5px;
  font-weight:500;
  display:grid;
  grid-template-columns:var(--nav-num) var(--nav-ico) minmax(0, 1fr) auto;
  align-items:center;
  column-gap:var(--nav-gap);
  opacity:.88;
  border:1px solid transparent;
  transition:background .15s, opacity .15s, border-color .15s;
}
.nav .nav-home{
  grid-template-columns:var(--nav-ico) minmax(0, 1fr);
  padding-left:12px;
  margin-bottom:4px;
}
.nav a:hover, .nav .nav-home:hover, .nav .nav-course:hover{
  background:var(--card); text-decoration:none; opacity:1;
}
.nav a.active, .nav .nav-home.active, .nav .nav-course.active{
  background:var(--card); opacity:1; border-color:var(--border);
  font-weight:600;
}

.nav .nav-num{
  width:var(--nav-num);
  height:22px;
  display:flex; align-items:center; justify-content:center;
  font-size:10px; font-weight:700; font-variant-numeric:tabular-nums;
  border-radius:5px;
  background:var(--tag); color:var(--accent-2);
  flex-shrink:0;
}
.nav .nav-num-sm{
  width:38px; height:18px;
  font-size:9.5px; font-weight:600;
  color:var(--muted); background:transparent;
  justify-content:flex-end;
  padding-right:1px;
}

.nav .nav-ico,
.nav .nav-ico-sm,
.grp-icon,
.grp-chevron{
  display:flex; align-items:center; justify-content:center;
  flex-shrink:0;
}
.nav .nav-ico{
  width:var(--nav-ico); height:var(--nav-ico);
  border-radius:6px;
  background:var(--tag);
  color:var(--accent-2);
}
.nav .nav-ico-home{
  width:var(--nav-ico); height:var(--nav-ico);
  border-radius:6px;
  background:var(--tag);
  color:var(--accent-2);
}
.nav .nav-ico .ico-svg{width:15px; height:15px}
.nav .nav-ico-home .ico-svg{width:15px; height:15px}

.nav .nav-ico-sm{
  width:18px; height:18px;
  border-radius:4px;
  background:transparent;
  color:var(--muted);
  opacity:.85;
}
.nav .nav-ico-sm .ico-svg{width:12px; height:12px}

.nav .nav-text{
  min-width:0;
  line-height:1.35;
  white-space:nowrap; overflow:hidden; text-overflow:ellipsis;
}

.nav a .badge, .nav .nav-course .badge{
  font-size:9px; font-weight:700; letter-spacing:.04em; text-transform:uppercase;
  padding:2px 6px; border-radius:999px;
  background:var(--tag); color:var(--muted);
}
.nav a .badge.soon, .nav .nav-course .badge.soon{color:var(--warn)}
.nav a .badge.live, .nav .nav-course .badge.live{color:var(--good)}

/* Section submenu */
.nav-sections{
  margin:2px 4px 6px 18px;
  padding:3px 0 3px 10px;
  border-left:2px solid var(--border);
  display:flex; flex-direction:column; gap:0;
}
.nav a.section{
  grid-template-columns:38px 16px minmax(0, 1fr);
  min-height:28px;
  padding:3px 6px 3px 4px;
  font-size:12px; font-weight:400;
  opacity:.8; border-radius:5px;
  border:1px solid transparent;
}
.nav a.section .nav-text{
  white-space:normal;
  line-height:1.35;
  display:-webkit-box;
  -webkit-line-clamp:2;
  -webkit-box-orient:vertical;
  overflow:hidden;
}
.nav a.section:hover{opacity:1; background:var(--bg-soft)}
.nav a.section.active{
  opacity:1; font-weight:600;
  background:var(--card); border-color:var(--border);
}
.nav a.section.active .nav-ico-sm{color:var(--accent-2); opacity:1}
.nav a.section.active .nav-num-sm{color:var(--accent)}

/* Collapsible sidebar groups */
.nav-group{margin-bottom:4px}
.nav-group:first-of-type .grp-toggle{margin-top:4px}

.grp-toggle{
  width:100%;
  min-height:34px;
  display:grid;
  grid-template-columns:14px 22px minmax(0, 1fr) auto;
  align-items:center;
  column-gap:8px;
  padding:5px 8px;
  margin:10px 0 3px;
  border:1px solid transparent; border-radius:8px;
  background:transparent; color:var(--muted);
  font-family:inherit; font-size:11px; font-weight:700;
  letter-spacing:.06em; text-transform:uppercase;
  cursor:pointer; text-align:left;
  transition:background .15s, color .15s, border-color .15s;
}
.grp-toggle:hover{
  background:var(--card); color:var(--text);
  border-color:var(--border);
}
.grp-toggle.grp-rust{color:var(--accent-2)}
.grp-toggle.grp-backend{color:var(--accent)}
.grp-toggle.grp-devops{color:var(--warn)}
.grp-toggle.grp-agentic-ai{color:var(--tech)}
.grp-toggle.grp-more{color:var(--muted)}

.grp-chevron{
  width:14px; height:14px;
  color:var(--muted);
  transition:transform .2s ease;
}
.grp-chevron .ico-svg{width:12px; height:12px}
.nav-group.open .grp-chevron{transform:rotate(90deg)}

.grp-icon{
  width:22px; height:22px;
  border-radius:6px;
  background:var(--tag);
  color:var(--accent-2);
}
.grp-icon .ico-svg{width:14px; height:14px}
.grp-toggle.grp-backend .grp-icon{color:var(--accent)}
.grp-toggle.grp-devops .grp-icon{color:var(--warn)}
.grp-toggle.grp-agentic-ai .grp-icon{color:var(--tech)}

.grp-label{
  min-width:0;
  text-transform:none; letter-spacing:0;
  font-size:12px; font-weight:600;
  white-space:nowrap; overflow:hidden; text-overflow:ellipsis;
}

.grp-count{
  font-size:10px; padding:1px 6px; border-radius:999px;
  background:var(--tag); color:var(--muted); font-weight:700;
  letter-spacing:0; text-transform:none;
}

.grp-body{
  display:flex; flex-direction:column; gap:2px;
  padding-left:2px;
  overflow:hidden;
  max-height:2400px;
  opacity:1;
  transition:max-height .28s ease, opacity .2s ease, margin .2s ease;
}
.nav-group.collapsed .grp-body{
  max-height:0;
  opacity:0;
  margin-top:0;
  pointer-events:none;
}

.sidebar-footer{
  margin-top:18px; padding-top:14px; border-top:1px solid var(--border);
  display:flex; gap:8px; flex-wrap:wrap;
}

.main{padding:32px 36px 80px; max-width:1200px}
.main p{max-width:75ch; line-height:1.7}
.main > p, .topic p, .level p{margin-bottom:12px}

/* Mobile sidebar toggle */
.sidebar-toggle{
  display:none;
  position:fixed; top:12px; left:12px; z-index:30;
  width:44px; height:44px; border-radius:12px;
  background:var(--card); border:1px solid var(--border);
  color:var(--text); font-size:22px; cursor:pointer;
  place-items:center; box-shadow:var(--shadow);
  -webkit-tap-highlight-color:transparent;
}
.sidebar-overlay{
  display:none;
  position:fixed; inset:0; z-index:15;
  background:rgba(0,0,0,.5);
  backdrop-filter:blur(2px);
}

@media (max-width: 900px){
  .shell{grid-template-columns: 1fr}
  .sidebar{
    position:fixed; top:0; left:0; bottom:0; width:300px; height:100vh;
    border-right:1px solid var(--border); border-bottom:none;
    transform:translateX(-100%);
    transition:transform .25s ease;
  }
  .sidebar.open{transform:translateX(0)}
  .sidebar-overlay.open{display:block}
  .sidebar-toggle{display:grid}
  .main{padding:20px 16px 80px; padding-top:64px}
  .nav{flex-direction:column; flex-wrap:nowrap}
  .nav .grp{width:auto}
  .nav a, .nav .nav-home, .nav .nav-course{min-height:44px}
  .nav a.section{min-height:40px}
  .nav-sections{margin-left:20px}
  .hero h2{font-size:clamp(22px, 5vw, 32px)}
  .toolbar{top:0; border-radius:0; margin-left:-16px; margin-right:-16px}
}

/* Hero */
.hero{
  border:1px solid var(--border);
  background:
    radial-gradient(600px 200px at 10% 0%, var(--glow-calm), transparent 60%),
    linear-gradient(135deg, var(--card), var(--card-2));
  padding:32px; border-radius:20px; box-shadow:var(--shadow);
  position:relative; overflow:hidden;
}
.hero::after{
  content:""; position:absolute; right:-60px; top:-60px; width:280px; height:280px;
  background: conic-gradient(from 0deg, var(--accent), var(--accent-2), var(--accent));
  filter: blur(60px); opacity:.3; border-radius:50%;
}
.hero::before{
  content:""; position:absolute; top:0; right:0; width:42%; height:100%;
  background:repeating-linear-gradient(135deg, transparent 0 16px, rgba(255,107,44,.055) 16px 17px);
  pointer-events:none;
}
[data-theme="light"] .hero::before{
  background:repeating-linear-gradient(135deg, transparent 0 16px, rgba(232,89,12,.045) 16px 17px);
}
.eyebrow{
  display:inline-block; font-size:11px; letter-spacing:.24em; text-transform:uppercase;
  font-weight:600;
  padding:6px 12px; border-radius:6px; background:var(--tag); color:var(--accent);
  border:1px solid var(--border);
}
.hero h2{font-size: clamp(28px, 4vw, 44px); margin:14px 0 6px; line-height:1.1; letter-spacing:-.5px}
.hero h2 span{background:linear-gradient(90deg,var(--accent),var(--accent-2)); -webkit-background-clip:text; background-clip:text; color:transparent}
.hero p{color:var(--muted); max-width:780px; font-size:16px}
.hero-meta{display:flex; flex-wrap:wrap; gap:10px; margin-top:18px}
.pill{padding:8px 12px; border-radius:999px; background:var(--tag); border:1px solid var(--border); font-size:13px; color:var(--text)}
.pill b{color:var(--accent-2)}

/* Toolbar */
.toolbar{
  margin: 24px 0; display:flex; gap:10px; flex-wrap:wrap; align-items:center;
  padding:12px; border-radius:14px; border:1px solid var(--border);
  background:var(--card); box-shadow:var(--shadow);
  position:sticky; top:8px; z-index:5;
}
.search{
  flex:1; display:flex; align-items:center; gap:10px;
  background:var(--bg-soft); border:1px solid var(--border); border-radius:10px; padding:10px 12px;
}
.search input{
  flex:1; background:transparent; border:none; outline:none; color:var(--text); font-size:15px;
}
.btn{
  border:1px solid var(--border); background:var(--bg-soft); color:var(--text);
  padding:9px 14px; border-radius:10px; cursor:pointer; font-size:13px;
  display:inline-flex; align-items:center; gap:6px;
  font-family:inherit;
}
.btn:hover{background:var(--card-2)}
.btn.primary{background:linear-gradient(135deg,var(--accent),var(--accent-2)); color:var(--on-accent); border:none; font-weight:700}
.btn.sm{padding:6px 10px; font-size:12px}

/* Sections (generic) */
section{margin: 48px 0}
section + section{border-top:1px solid var(--border); padding-top:48px}
.section-head{display:flex; justify-content:space-between; align-items:end; flex-wrap:wrap; gap:10px; margin-bottom:14px}
.section-head h3{font-size:24px; margin:0; letter-spacing:-.3px}
.section-head .sub{color:var(--muted); font-size:14px}

/* Course catalog (home page) */
.course-grid{
  display:grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap:16px; margin-top:24px;
}
.course-card{
  border:1px solid var(--border); background:var(--card); border-radius:var(--radius);
  padding:18px; box-shadow:var(--shadow); transition:transform .15s, border-color .15s;
  display:flex; flex-direction:column; gap:10px;
  color:var(--text); text-decoration:none;
  position:relative; overflow:hidden;
}
.course-card:hover{transform:translateY(-3px); border-color:var(--accent); text-decoration:none}
.course-card .cc-icon{
  width:48px;height:48px;border-radius:12px;
  background:linear-gradient(135deg, var(--glow-warm), var(--glow-calm));
  display:grid; place-items:center; font-size:24px;
  border:1px solid var(--border);
}
.course-card h4{margin:0; font-size:18px; letter-spacing:-.2px}
.course-card p{margin:0; color:var(--muted); font-size:14px; flex:1}
.course-card .cc-meta{
  display:flex; gap:8px; flex-wrap:wrap; align-items:center;
  font-size:12px; color:var(--muted); margin-top:6px;
}
.course-card .cc-tag{
  padding:3px 8px; border-radius:999px; background:var(--tag); border:1px solid var(--border);
}
.course-card .cc-status{
  padding:3px 8px; border-radius:999px; font-weight:700; font-size:11px;
  text-transform:uppercase; letter-spacing:.06em;
}
.course-card .cc-status.live{background:rgba(46,204,113,.12); color:var(--good); border:1px solid rgba(46,204,113,.3)}
.course-card .cc-status.draft{background:rgba(255,176,32,.12); color:var(--warn); border:1px solid rgba(255,176,32,.3)}
.course-card .cc-status.soon{background:var(--tag); color:var(--muted); border:1px solid var(--border)}

/* Generic content blocks (callouts, tech-block) — reused across courses */
.callout{
  border:1px solid var(--border); border-left:4px solid var(--accent);
  background:linear-gradient(180deg, var(--glow-calm), transparent);
  padding:14px 16px; border-radius:10px; margin:14px 0;
}
.callout.good{border-left-color:var(--good); background:linear-gradient(180deg, var(--glow-good), transparent)}
.callout.warn{border-left-color:var(--warn); background:linear-gradient(180deg, var(--glow-warm), transparent)}
.callout h5{margin:0 0 6px; font-size:14px; text-transform:uppercase; letter-spacing:.08em; color:var(--accent-2)}

.tech-block{border:1px solid var(--border); border-radius:14px; background:var(--card); padding:16px; margin-bottom:14px}
.tech-block h5{margin:0 0 8px; font-size:16px; color:var(--accent-2)}
.tech-block .phrase{
  padding:8px 10px; background:var(--bg-soft); border:1px solid var(--border);
  border-radius:8px; margin:6px 0; font-size:14px;
}
.tech-block .phrase b{color:var(--accent-2)}
.tech-block .phrase em{color:var(--hindi); font-style:normal; display:block; font-size:12px; margin-top:2px}

.grid-2{display:grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap:12px}

/* Code blocks */
pre.code{
  position:relative;
  background:var(--code-bg); border:1px solid var(--border); border-left:3px solid var(--accent-2);
  border-radius:10px;
  padding:18px 20px; overflow:auto; font-size:13.5px; line-height:1.7;
  color:var(--code-text); font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  tab-size:2; -moz-tab-size:2;
  -webkit-overflow-scrolling:touch;
}
pre.code::selection, pre.code *::selection{background:rgba(255, 107, 44, 0.28)}
[data-theme="light"] pre.code{background:var(--code-bg); color:var(--code-text)}
code.inline{
  background:var(--tag); border:1px solid var(--border); border-radius:6px;
  padding:1px 6px; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size:13px;
}

/* Copy button on code blocks */
.copy-btn{
  position:absolute; top:8px; right:8px;
  padding:4px 10px; border-radius:8px;
  background:rgba(255,255,255,.08); border:1px solid rgba(255,255,255,.12);
  color:rgba(255,255,255,.5);
  font-size:12px; font-family:inherit; cursor:pointer;
  opacity:0; transition: opacity .2s, background .15s, color .15s;
  z-index:2;
}
pre.code:hover .copy-btn{opacity:1}
.copy-btn:hover{background:rgba(255,255,255,.15); color:#fff}
.copy-btn.copied{background:rgba(46,204,113,.2); color:var(--good); border-color:rgba(46,204,113,.3)}

/* Level cards */
.level{margin:36px 0}

/* Topic cards */
.topic{margin-bottom:20px}
.topic p{line-height:1.7}

/* Lists inside content */
.topic ul, .topic ol, .main ul, .main ol{
  padding-left:24px; margin:8px 0;
}
.topic ul li, .topic ol li, .main > ul li, .main > ol li{
  margin:8px 0; line-height:1.65;
}
.topic ul li::marker{color:var(--accent)}
.topic ol li::marker{color:var(--accent-2); font-weight:700}
.topic ul ul, .topic ol ol, .topic ul ol, .topic ol ul{
  margin-top:4px; margin-bottom:4px;
}

/* Tables */
.table-wrap{
  overflow-x:auto; -webkit-overflow-scrolling:touch;
  border-radius:12px; border:1px solid var(--border); margin:12px 0;
}
.table-wrap .stack-table{border:none; border-radius:0}
.stack-table th{position:sticky; top:0; z-index:1}
.stack-table tbody tr:nth-child(even) td{background:var(--glow-calm)}
[data-theme="light"] .stack-table tbody tr:nth-child(even) td{background:rgba(0,0,0,.02)}
.stack-table td{padding:10px 12px}

/* Details / Q&A */
details.q{
  border:1px solid var(--border); border-radius:12px;
  background:var(--card); margin:12px 0;
  overflow:hidden;
}
details.q summary{
  padding:14px 18px; cursor:pointer; font-weight:600; font-size:15px;
  list-style:none; display:flex; align-items:center; gap:10px;
  transition:background .15s;
}
details.q summary::-webkit-details-marker{display:none}
details.q summary::before{
  content:"▸"; display:inline-block; font-size:12px; color:var(--accent);
  transition:transform .2s;
  flex-shrink:0;
}
details.q[open] summary::before{transform:rotate(90deg)}
details.q summary:hover{background:var(--card-2)}
details.q[open] summary{border-bottom:1px solid var(--border)}
details.q > p, details.q > div{
  padding:14px 18px; line-height:1.7; color:var(--muted);
}

/* Footer */
footer{
  margin-top:60px; padding-top:20px; border-top:1px solid var(--border);
  color:var(--muted); font-size:13px; text-align:center;
}
footer b{color:var(--text)}

/* Empty / coming-soon state */
.empty{padding:50px 30px; text-align:center; color:var(--muted); border:1px dashed var(--border); border-radius:14px; margin:20px 0}
.empty h4{margin:0 0 8px; font-size:18px; color:var(--text)}

/* Scrollbars */
::-webkit-scrollbar{width:10px;height:10px}
::-webkit-scrollbar-thumb{background:var(--border); border-radius:10px}
::-webkit-scrollbar-thumb:hover{background:var(--accent)}

/* =========================================================
   Accessibility
   ========================================================= */

/* Skip-to-content */
.skip-link{
  position:absolute; top:-100%; left:16px; z-index:100;
  padding:10px 18px; border-radius:10px;
  background:var(--accent); color:#fff; font-weight:700; font-size:14px;
  text-decoration:none;
  transition:top .2s;
}
.skip-link:focus{top:12px}

/* Focus-visible on all interactive elements */
a:focus-visible,
button:focus-visible,
summary:focus-visible,
input:focus-visible,
select:focus-visible,
[tabindex]:focus-visible{
  outline:2px solid var(--accent);
  outline-offset:3px;
  border-radius:4px;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce){
  *, *::before, *::after{
    animation-duration:0.01ms !important;
    animation-iteration-count:1 !important;
    transition-duration:0.01ms !important;
    scroll-behavior:auto !important;
  }
  html{scroll-behavior:auto}
}

/* =========================================================
   Reading Progress Bar
   ========================================================= */
.reading-progress{
  position:fixed; top:0; left:0; z-index:50;
  height:3px; width:0;
  background:linear-gradient(90deg, var(--accent), var(--accent-2));
  transition:none;
  pointer-events:none;
}

/* =========================================================
   Back-to-Top Button
   ========================================================= */
.back-to-top{
  position:fixed; bottom:28px; right:28px; z-index:25;
  width:44px; height:44px; border-radius:50%;
  background:linear-gradient(135deg, var(--accent), var(--accent-2));
  color:var(--on-accent); border:none; cursor:pointer;
  font-size:20px; font-weight:900;
  display:grid; place-items:center;
  box-shadow:0 4px 20px rgba(255, 107, 44, 0.35);
  opacity:0; transform:translateY(12px);
  transition:opacity .25s, transform .25s;
  pointer-events:none;
  -webkit-tap-highlight-color:transparent;
}
.back-to-top.visible{
  opacity:1; transform:translateY(0);
  pointer-events:auto;
}
.back-to-top:hover{
  box-shadow:0 6px 28px rgba(255, 107, 44, 0.45);
}
[data-theme="light"] .back-to-top{
  box-shadow:0 4px 20px rgba(61, 158, 150, 0.22);
}

/* =========================================================
   Print
   ========================================================= */
@media print{
  .sidebar, .toolbar, .btn, .back-to-top, .reading-progress, .sidebar-toggle, .sidebar-overlay, .copy-btn{display:none !important}
  .shell{grid-template-columns: 1fr}
  body{background:#fff; color:#000; font-size:12pt; line-height:1.6}
  .main{max-width:100%; padding:0}
  .callout, .tech-block, .course-card, .hero{box-shadow:none; border-color:#ccc}
  pre.code{white-space:pre-wrap; word-break:break-all; border-left-color:#999}
  a{color:#000; text-decoration:underline}
  a[href^="http"]::after{content:" (" attr(href) ")"; font-size:9pt; color:#666}
  section + section{border-top-color:#ccc}
  .topic, .level{break-inside:avoid}
}

/* =========================================================
   Mobile refinements
   ========================================================= */
@media (max-width: 900px){
  pre.code{
    font-size:12.5px; padding:14px;
    border-radius:8px;
    max-width:calc(100vw - 32px);
  }
  .course-card{width:100%}
  .grid-2, .twocol, .threecol{grid-template-columns:1fr}
  section{margin:32px 0}
  section + section{padding-top:32px}
  .back-to-top{bottom:20px; right:16px; width:40px; height:40px; font-size:18px}
}

/* Warm code/ascii blocks — overrides course-local hardcoded tints */
.ascii, pre.code{
  background:var(--code-bg) !important;
  color:var(--code-text) !important;
}
[data-theme="light"] .ascii,
[data-theme="light"] pre.code{
  background:var(--code-bg) !important;
  color:var(--code-text) !important;
}

/* Gradient CTAs — warm on-accent text for readability */
.lvl-tag, .filter-chip.active, .hero-cta, .topic-pill.active{
  color:var(--on-accent) !important;
}

@media (max-width: 480px){
  body{font-size:15px}
  .main{padding:16px 12px 80px; padding-top:60px}
  .hero{padding:20px; border-radius:14px}
  .hero p{font-size:14px}
}