/* Shared chrome — landing, lab, spec, geometry, dashboard nav */
:root {
  --bg: #08080f;
  --card: #161b22;
  --line: #21262d;
  --text: #e8e8f0;
  --muted: #c4cdd6;
  --accent: #58a6ff;
  --banner-bg: #7c2d12;
  --banner-fg: #ffedd5;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: 'Segoe UI', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}
a { color: var(--accent); }
.site-nav {
  background: #0d1117;
  border-bottom: 1px solid var(--line);
  padding: 10px 16px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
  align-items: center;
}
.site-nav .brand {
  font-weight: 800;
  color: var(--accent);
  margin-left: auto;
  text-decoration: none;
}
.site-nav a { text-decoration: none; font-size: 0.85rem; color: var(--muted); }
.site-nav a:hover, .site-nav a.on { color: var(--text); }
.nav-more { position: relative; }
.nav-more > summary {
  list-style: none;
  cursor: pointer;
  font-size: 0.85rem;
  color: var(--muted);
  font-weight: 600;
  padding: 4px 2px;
}
.nav-more > summary::-webkit-details-marker { display: none; }
.nav-more[open] > summary { color: var(--text); }
.nav-more-list {
  position: absolute;
  inset-inline-start: 0;
  top: calc(100% + 6px);
  background: #161b22;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 6px;
  display: flex;
  flex-direction: column;
  min-width: 188px;
  z-index: 30;
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.45);
}
.nav-more-list a { padding: 8px 10px; border-radius: 8px; }
.nav-more-list a:hover, .nav-more-list a.on { background: #21262d; }
@media (max-width: 560px) {
  .site-nav > a.nav-mid { display: none; }
  .nav-more-list { position: static; min-width: 0; width: 100%; box-shadow: none; }
}
.banner {
  background: var(--banner-bg);
  color: var(--banner-fg);
  font: 700 0.8rem system-ui, sans-serif;
  padding: 8px 16px;
  text-align: center;
  border-bottom: 1px solid rgba(255,255,255,.12);
}
.wrap { max-width: 1120px; margin: 0 auto; padding: 22px 16px 56px; }
.wrap h1 { font-size: 1.55rem; font-weight: 800; margin-bottom: 6px; }
.lead { color: var(--muted); font-size: 0.9rem; line-height: 1.65; margin-bottom: 18px; max-width: 74ch; }
.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 16px;
}
.card h2 {
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 12px;
}
.btn {
  background: #0d1117;
  border: 1px solid #30363d;
  color: #c9d1d9;
  border-radius: 8px;
  padding: 8px 12px;
  cursor: pointer;
  font: 600 0.8rem inherit;
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn.on { background: #1f4068; border-color: var(--accent); color: var(--accent); }
.btn.danger.on { background: #3a1010; border-color: #f85149; color: #f85149; }
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}
.skip-link {
  position: absolute;
  right: 12px;
  top: -48px;
  z-index: 4000;
  background: #1f6feb;
  color: #fff;
  padding: 8px 14px;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 700;
}
.skip-link:focus { top: 12px; }
@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;
  }
}