:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --surface-2: #f1f3f6;
  --text: #1c2330;
  --muted: #5d6879;
  --border: #e2e6ec;
  --accent: #2563eb;
  --accent-soft: #e6eefe;
  --ok: #16a34a;
  --ok-soft: #e7f6ec;
  --code-bg: #0f1623;
  --code-text: #e4e9f2;
  --code-comment: #7d8ba1;
  --tip: #16a34a;   --tip-bg: #ecf8f0;
  --note: #2563eb;  --note-bg: #edf3fe;
  --warn: #d97706;  --warn-bg: #fdf5e8;
  --cost: #dc2626;  --cost-bg: #fdeeee;
  --radius: 10px;
  --topbar-h: 58px;
  --font: "Segoe UI", system-ui, -apple-system, Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: "Cascadia Code", "JetBrains Mono", Consolas, "SFMono-Regular", Menlo, monospace;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0d1117; --surface: #151b24; --surface-2: #1c2430; --text: #e6eaf0; --muted: #9aa5b5;
    --border: #2a3340; --accent: #6ea0ff; --accent-soft: #1b2a45; --ok: #3fb96a; --ok-soft: #15291d;
    --code-bg: #0a0e14; --tip-bg: #13261a; --note-bg: #142035; --warn-bg: #2b2112; --cost-bg: #2e1616;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0d1117; --surface: #151b24; --surface-2: #1c2430; --text: #e6eaf0; --muted: #9aa5b5;
  --border: #2a3340; --accent: #6ea0ff; --accent-soft: #1b2a45; --ok: #3fb96a; --ok-soft: #15291d;
  --code-bg: #0a0e14; --tip-bg: #13261a; --note-bg: #142035; --warn-bg: #2b2112; --cost-bg: #2e1616;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { scroll-padding-top: calc(var(--topbar-h) + 16px); }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.65 var(--font); -webkit-font-smoothing: antialiased; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
code { font-family: var(--mono); font-size: .88em; background: var(--surface-2); border: 1px solid var(--border); padding: .08em .35em; border-radius: 5px; }
main:focus { outline: none; }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 30; height: var(--topbar-h);
  display: flex; align-items: center; gap: 14px; padding: 0 18px;
  background: color-mix(in srgb, var(--surface) 92%, transparent); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; color: var(--text); white-space: nowrap; }
.brand:hover { text-decoration: none; }
.logo { display: grid; place-items: center; width: 30px; height: 30px; border-radius: 8px; background: var(--accent); color: #fff; font-size: 18px; }
.search { position: relative; flex: 1; max-width: 520px; margin-left: auto; }
.search input {
  width: 100%; height: 38px; padding: 0 14px; border-radius: 8px; border: 1px solid var(--border);
  background: var(--surface-2); color: var(--text); font: inherit; font-size: 14px;
}
.search input:focus { outline: 2px solid var(--accent); outline-offset: -1px; background: var(--surface); }
.results {
  position: absolute; top: 44px; left: 0; right: 0; max-height: 70vh; overflow: auto;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: 0 12px 32px rgba(0,0,0,.18); padding: 6px;
}
.results a { display: flex; gap: 10px; align-items: flex-start; padding: 8px 10px; border-radius: 8px; color: var(--text); }
.results a:hover { background: var(--surface-2); text-decoration: none; }
.results small { display: block; color: var(--muted); font-size: 12.5px; line-height: 1.4; }
.results mark { background: #fde68a; color: #1c2330; border-radius: 2px; }
.no-results { padding: 12px; color: var(--muted); font-size: 14px; }
.icon-btn {
  width: 38px; height: 38px; border-radius: 8px; border: 1px solid var(--border); background: var(--surface);
  color: var(--text); font-size: 17px; cursor: pointer; flex: none;
}
.icon-btn:hover { background: var(--surface-2); }
.menu-btn { display: none; }

/* ---------- layout ---------- */
.layout { display: grid; grid-template-columns: 270px minmax(0, 1fr) 230px; max-width: 1480px; margin: 0 auto; }
.sidebar, .toc {
  position: sticky; top: var(--topbar-h); height: calc(100vh - var(--topbar-h)); overflow-y: auto; padding: 20px 14px;
}
.sidebar { border-right: 1px solid var(--border); }
.main { padding: 32px 48px 80px; min-width: 0; }

.nav-home, .nav-item { display: flex; align-items: center; gap: 10px; padding: 8px 10px; border-radius: 8px; color: var(--text); font-size: 14.5px; }
.nav-home:hover, .nav-item:hover { background: var(--surface-2); text-decoration: none; }
.nav-home.active, .nav-item.active { background: var(--accent-soft); }
.nav-label, .toc-label { margin: 18px 10px 6px; font-size: 11.5px; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.nav-text { flex: 1; min-width: 0; }
.nav-title { display: block; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.nav-pct { font-size: 11.5px; color: var(--muted); font-variant-numeric: tabular-nums; }
.mini-bar { display: block; height: 3px; margin-top: 4px; border-radius: 2px; background: var(--border); overflow: hidden; }
.mini-bar span { display: block; height: 100%; background: var(--ok); transition: width .3s; }

.badge {
  --c: var(--accent);
  display: inline-grid; place-items: center; flex: none; min-width: 32px; height: 26px; padding: 0 6px;
  border-radius: 6px; font: 700 11.5px/1 var(--font); color: #fff; background: var(--c);
}
.badge.big { min-width: 48px; height: 40px; font-size: 14px; border-radius: 10px; }

.toc { border-left: 1px solid var(--border); font-size: 13.5px; }
.toc a { display: block; padding: 5px 10px; color: var(--muted); border-left: 2px solid transparent; line-height: 1.4; }
.toc a:hover { color: var(--text); text-decoration: none; }
.toc a.active { color: var(--accent); border-left-color: var(--accent); }
.toc a.done::before { content: "✓ "; color: var(--ok); }

/* ---------- home ---------- */
.hero { padding: 24px 0 8px; max-width: 860px; }
.eyebrow { margin: 0 0 6px; font-size: 12.5px; font-weight: 700; letter-spacing: .07em; text-transform: uppercase; color: var(--muted); }
.hero h1 { font-size: clamp(28px, 4vw, 42px); line-height: 1.15; margin: 0 0 14px; letter-spacing: -.02em; }
.lead { font-size: 18px; color: var(--muted); margin: 0 0 22px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; }
.btn {
  display: inline-flex; align-items: center; padding: 10px 18px; border-radius: 8px; font-weight: 600; font-size: 15px;
  border: 1px solid var(--border); background: var(--surface); color: var(--text);
}
.btn:hover { text-decoration: none; background: var(--surface-2); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.primary:hover { filter: brightness(1.08); }
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin-top: 28px; max-width: 620px; }
.stats div { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 12px 14px; }
.stats strong { display: block; font-size: 24px; font-variant-numeric: tabular-nums; }
.stats span { font-size: 13px; color: var(--muted); }
.section-title { font-size: 22px; margin: 44px 0 16px; }

.roadmap { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 16px; }
.road-card a {
  display: flex; flex-direction: column; height: 100%; padding: 18px; color: var(--text);
  background: var(--surface); border: 1px solid var(--border); border-top: 4px solid var(--c); border-radius: var(--radius);
  transition: transform .15s, box-shadow .15s;
}
.road-card a:hover { text-decoration: none; transform: translateY(-2px); box-shadow: 0 8px 22px rgba(0,0,0,.08); }
.road-top { display: flex; justify-content: space-between; align-items: center; }
.step-chip { font-size: 12px; color: var(--muted); font-weight: 600; }
.road-card h3 { margin: 12px 0 4px; font-size: 18px; }
.road-card p { margin: 0 0 14px; color: var(--muted); font-size: 14px; flex: 1; }
.road-meta { display: flex; gap: 12px; font-size: 12.5px; color: var(--muted); margin-bottom: 10px; }
.bar { height: 6px; border-radius: 4px; background: var(--border); overflow: hidden; flex: 1; }
.bar span { display: block; height: 100%; background: var(--ok); transition: width .3s; }

.howto { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 16px; }
.howto div { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px 18px; }
.howto h3 { margin: 0 0 6px; font-size: 15.5px; }
.howto p { margin: 0; color: var(--muted); font-size: 14.5px; }
.pill { font-size: 12px; font-weight: 700; padding: 1px 8px; border-radius: 999px; }
.pill.cost { background: var(--cost-bg); color: var(--cost); }

/* ---------- guide ---------- */
.doc { max-width: 860px; }
.doc-head { display: flex; align-items: center; gap: 16px; }
.doc-head h1 { margin: 0; font-size: 34px; line-height: 1.2; letter-spacing: -.01em; }
.progress-row { display: flex; align-items: center; gap: 12px; margin: 20px 0 8px; font-size: 13.5px; color: var(--muted); }
.link-btn { background: none; border: 0; color: var(--muted); font: inherit; font-size: 13px; cursor: pointer; text-decoration: underline; padding: 0; }
.intro { font-size: 17px; }
.intro p { color: var(--muted); }

.step {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 6px 26px 14px; margin: 18px 0;
}
.step.is-done { border-color: color-mix(in srgb, var(--ok) 45%, var(--border)); }
.step-head { display: flex; align-items: center; gap: 12px; padding: 14px 0 4px; }
.step-head h2 { flex: 1; margin: 0; font-size: 21px; line-height: 1.3; }
.step-head h2 a { color: var(--text); }
.step-num {
  display: grid; place-items: center; flex: none; width: 30px; height: 30px; border-radius: 50%;
  background: var(--surface-2); border: 1px solid var(--border); font-weight: 700; font-size: 13.5px;
}
.step.is-done .step-num { background: var(--ok); border-color: var(--ok); color: #fff; font-size: 0; }
.step.is-done .step-num::after { content: "✓"; font-size: 15px; }
.done-toggle {
  display: inline-flex; align-items: center; gap: 6px; font-size: 13.5px; color: var(--muted); cursor: pointer;
  padding: 4px 10px; border: 1px solid var(--border); border-radius: 999px; user-select: none; white-space: nowrap;
}
.done-toggle:has(input:checked) { background: var(--ok-soft); color: var(--ok); border-color: var(--ok); }
.done-toggle input { accent-color: var(--ok); margin: 0; }

.step-body h3 { font-size: 17px; margin: 22px 0 6px; }
.step-body h4 { font-size: 15.5px; margin: 18px 0 4px; }
.step-body p, .step-body li { max-width: 74ch; }
.step-body ul, .step-body ol { padding-left: 22px; }
.step-body li { margin: 4px 0; }

.code { margin: 14px 0; border-radius: 8px; overflow: hidden; background: var(--code-bg); border: 1px solid #1f2937; }
.code-head { display: flex; justify-content: space-between; align-items: center; padding: 5px 8px 5px 14px; background: rgba(255,255,255,.05); color: #94a3b8; font: 600 11.5px/1 var(--mono); text-transform: lowercase; }
.copy { font: 600 12px var(--font); color: #cbd5e1; background: rgba(255,255,255,.07); border: 1px solid rgba(255,255,255,.12); border-radius: 6px; padding: 4px 10px; cursor: pointer; }
.copy:hover { background: rgba(255,255,255,.14); }
.copy.ok { color: #86efac; border-color: #86efac; }
.code pre { margin: 0; padding: 14px 16px; overflow-x: auto; }
.code code { background: none; border: 0; padding: 0; color: var(--code-text); font-size: 13.5px; line-height: 1.6; white-space: pre; }
.code .c { color: var(--code-comment); font-style: italic; }

.callout { border-left: 4px solid var(--note); background: var(--note-bg); border-radius: 0 8px 8px 0; padding: 4px 16px; margin: 14px 0; }
.callout p { margin: 8px 0; }
.callout.tip { border-color: var(--tip); background: var(--tip-bg); }
.callout.warning { border-color: var(--warn); background: var(--warn-bg); }
.callout.cost { border-color: var(--cost); background: var(--cost-bg); }
.callout.why { border-color: #8b5cf6; background: color-mix(in srgb, #8b5cf6 10%, var(--surface)); }

.table-wrap { overflow-x: auto; margin: 14px 0; }
table { border-collapse: collapse; width: 100%; font-size: 14.5px; }
th, td { text-align: left; padding: 8px 12px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { background: var(--surface-2); font-weight: 600; }

.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 36px; flex-wrap: wrap; }
.empty { max-width: 640px; padding: 40px 0; }

/* ---------- practice lab ---------- */
.vm { margin: 16px 0; border: 1px solid #1f2937; border-radius: var(--radius); overflow: hidden; background: #000; }
.vm-bar { display: flex; align-items: center; gap: 10px; padding: 8px 10px 8px 14px; background: #111827; color: #cbd5e1; font-size: 13.5px; }
.vm-dot { width: 10px; height: 10px; border-radius: 50%; background: #64748b; flex: none; }
.vm[data-state="busy"] .vm-dot { background: #f59e0b; animation: pulse 1s infinite alternate; }
.vm[data-state="ready"] .vm-dot { background: #22c55e; }
.vm[data-state="error"] .vm-dot { background: #ef4444; }
.vm[data-state="error"] .vm-status { color: #fca5a5; }
@keyframes pulse { to { opacity: .35; } }
.vm-status { flex: 1; min-width: 0; }
.vm-actions .btn { padding: 6px 14px; font-size: 13.5px; }
.vm-actions .btn[hidden] { display: none; }
.vm-screen { min-height: 400px; padding: 8px; overflow-x: auto; }
.vm-placeholder { display: grid; place-items: center; min-height: 384px; text-align: center; color: #94a3b8; font-size: 15px; line-height: 1.7; padding: 0 16px; }
.vm-try { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; padding: 10px 12px; background: #111827; border-top: 1px solid #1f2937; }
.vm-try span { color: #94a3b8; font-size: 13px; margin-right: 4px; }
.chip { font: 600 12.5px var(--font); color: #e2e8f0; background: #1f2937; border: 1px solid #334155; border-radius: 999px; padding: 4px 11px; cursor: pointer; }
.chip:hover { background: #334155; }

/* ---------- responsive ---------- */
@media (max-width: 1180px) {
  .layout { grid-template-columns: 250px minmax(0, 1fr); }
  .toc { display: none; }
}
@media (max-width: 860px) {
  .layout { grid-template-columns: minmax(0, 1fr); }
  .menu-btn { display: block; }
  .sidebar {
    position: fixed; top: var(--topbar-h); left: 0; bottom: 0; height: auto; width: 290px; z-index: 25;
    background: var(--surface); transform: translateX(-100%); transition: transform .2s;
  }
  body.menu-open .sidebar { transform: none; box-shadow: 8px 0 30px rgba(0,0,0,.2); }
  .scrim { position: fixed; inset: var(--topbar-h) 0 0 0; background: rgba(0,0,0,.35); z-index: 20; }
  .main { padding: 22px 16px 60px; }
  .brand span:last-child { display: none; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .step { padding: 4px 16px 12px; }
  .step-head { flex-wrap: wrap; }
  .doc-head h1 { font-size: 27px; }
}