:root {
  --bg: #0d1117;
  --panel: #161b22;
  --border: #30363d;
  --text: #c9d1d9;
  --muted: #8b949e;
  --good: #3fb950;
  --bad: #f85149;
  --warn: #d29922;
  --link: #79c0ff;
  --code-bg: #0d1117;
  --accent: #58a6ff;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  font-size: 15px;
  line-height: 1.6;
}

a { color: var(--link); }
a:hover { text-decoration: underline; }

code, .mono {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9em;
}
p code, li code, td code, .section-note code {
  background: var(--code-bg);
  padding: 1px 5px;
  border-radius: 3px;
  border: 1px solid var(--border);
  font-size: 12.5px;
}

.layout {
  display: grid;
  grid-template-columns: 240px minmax(0, 1fr);
  min-height: 100vh;
}

.sidebar {
  border-right: 1px solid var(--border);
  background: #0b0f14;
  padding: 28px 18px 48px;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}

.sidebar .brand {
  display: block;
  font-size: 13px;
  color: var(--muted);
  text-decoration: none;
  margin-bottom: 4px;
}
.sidebar .brand:hover { color: var(--link); }

.sidebar h1 {
  font-size: 18px;
  margin: 0 0 20px;
  font-weight: 600;
}

.sidebar nav a {
  display: block;
  padding: 7px 10px;
  border-radius: 6px;
  color: var(--text);
  text-decoration: none;
  font-size: 13.5px;
  margin-bottom: 2px;
}
.sidebar nav a:hover { background: #161b22; text-decoration: none; }
.sidebar nav a.active {
  background: rgba(88, 166, 255, 0.12);
  color: var(--accent);
}

.sidebar .nav-group {
  margin-top: 18px;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.55px;
  color: var(--muted);
  padding: 0 10px 6px;
}

.main {
  padding: 36px 40px 80px;
  max-width: 880px;
}

.main h1 {
  font-size: 28px;
  margin: 0 0 10px;
  line-height: 1.25;
}
.main h2 {
  font-size: 18px;
  margin: 36px 0 10px;
  padding-top: 8px;
  border-top: 1px solid var(--border);
}
.main h2:first-of-type { border-top: none; padding-top: 0; }
.main h3 {
  font-size: 15px;
  margin: 24px 0 8px;
  color: var(--text);
}

.lede {
  color: var(--muted);
  font-size: 15px;
  margin: 0 0 24px;
  max-width: 68ch;
}

.banner {
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 12px 14px;
  margin: 16px 0;
  font-size: 13.5px;
}
.banner.warn {
  background: rgba(210, 153, 34, 0.08);
  border-color: rgba(210, 153, 34, 0.4);
}
.banner.good {
  background: rgba(63, 185, 80, 0.08);
  border-color: rgba(63, 185, 80, 0.35);
}
.banner b { color: var(--warn); }
.banner.good b { color: var(--good); }

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 6px;
  overflow: hidden;
  margin: 14px 0 20px;
}

table { width: 100%; border-collapse: collapse; font-size: 13.5px; }
thead th {
  text-align: left;
  padding: 10px 14px;
  color: var(--muted);
  font-weight: 500;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  border-bottom: 1px solid var(--border);
  background: #161b22;
}
tbody td {
  padding: 10px 14px;
  border-bottom: 1px solid #21262d;
  vertical-align: top;
}
tbody tr:last-child td { border-bottom: none; }
tbody tr:hover { background: #1c2128; }

.steps {
  counter-reset: step;
  list-style: none;
  padding: 0;
  margin: 16px 0;
}
.steps > li {
  position: relative;
  padding: 0 0 22px 44px;
  border-left: 1px solid var(--border);
  margin-left: 14px;
}
.steps > li:last-child {
  border-left-color: transparent;
  padding-bottom: 0;
}
.steps > li::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: -14px;
  top: 0;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: #21262d;
  border: 1px solid var(--border);
  color: var(--accent);
  font-size: 12px;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
}
.steps > li > strong {
  display: block;
  margin-bottom: 6px;
}

.lang-tabs {
  display: flex;
  gap: 4px;
  margin: 14px 0 0;
  border-bottom: 1px solid var(--border);
}
.lang-tabs button {
  background: transparent;
  border: 1px solid transparent;
  border-bottom: none;
  color: var(--muted);
  padding: 8px 14px;
  border-radius: 6px 6px 0 0;
  cursor: pointer;
  font-size: 13px;
}
.lang-tabs button:hover { color: var(--text); }
.lang-tabs button.active {
  color: var(--text);
  background: var(--panel);
  border-color: var(--border);
  margin-bottom: -1px;
  padding-bottom: 9px;
}

.code-panel {
  display: none;
  position: relative;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 0 6px 6px 6px;
  margin: 0 0 18px;
}
.code-panel.active { display: block; }

.code-panel pre {
  margin: 0;
  padding: 14px 16px 16px;
  overflow-x: auto;
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--text);
}
.code-panel pre code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  background: none;
  border: none;
  padding: 0;
  font-size: inherit;
}

button.copy {
  position: absolute;
  top: 8px;
  right: 8px;
  background: #21262d;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 3px 9px;
  cursor: pointer;
  font-size: 11px;
}
button.copy:hover { background: #30363d; }
button.copy.ok { color: var(--good); border-color: rgba(63, 185, 80, 0.4); }

.toc {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 8px 0;
  margin: 20px 0 28px;
}
.toc a {
  display: block;
  padding: 10px 16px;
  text-decoration: none;
  color: var(--text);
  border-bottom: 1px solid #21262d;
}
.toc a:last-child { border-bottom: none; }
.toc a:hover { background: #1c2128; text-decoration: none; }
.toc a .num {
  color: var(--muted);
  font-variant-numeric: tabular-nums;
  margin-right: 10px;
  font-size: 12px;
}
.toc a .desc {
  display: block;
  color: var(--muted);
  font-size: 12.5px;
  margin: 2px 0 0 28px;
}

.diagram {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 16px 18px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 12px;
  line-height: 1.45;
  overflow-x: auto;
  white-space: pre;
  color: var(--muted);
  margin: 14px 0 20px;
}
.diagram .hi { color: var(--accent); }
.diagram .ok { color: var(--good); }

.next {
  margin-top: 40px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}
.next a {
  text-decoration: none;
  font-size: 14px;
}
.next a:hover { text-decoration: underline; }
.next .muted { color: var(--muted); font-size: 12px; display: block; }

@media (max-width: 860px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar {
    position: static;
    height: auto;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 18px 16px;
  }
  .sidebar nav {
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
  }
  .sidebar nav a { margin: 0; }
  .sidebar .nav-group { width: 100%; margin-top: 12px; }
  .main { padding: 24px 16px 64px; }
}