:root {
  color-scheme: dark;
  --bg: #0d1117;
  --panel: #161b22;
  --text: #e6edf3;
  --muted: #8b949e;
  --border: #30363d;
  --accent: #58a6ff;
}

* { box-sizing: border-box; }
html { background: var(--bg); }
body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
}
a { color: var(--accent); }
.site-header {
  display: flex;
  gap: 1.5rem;
  align-items: center;
  justify-content: space-between;
  padding: 1rem max(1rem, calc((100vw - 1080px) / 2));
  border-bottom: 1px solid var(--border);
  background: rgba(13, 17, 23, 0.96);
}
.brand { color: var(--text); font-weight: 800; text-decoration: none; }
nav { display: flex; flex-wrap: wrap; gap: 0.9rem; }
nav a { color: var(--muted); text-decoration: none; font-size: 0.95rem; }
nav a:hover { color: var(--text); }
main, footer { width: min(1080px, calc(100% - 2rem)); margin: 0 auto; }
main { padding: 4rem 0 3rem; }
footer { padding: 2rem 0 4rem; border-top: 1px solid var(--border); color: var(--muted); }
h1 { max-width: 900px; margin: 0.4rem 0 1rem; font-size: clamp(2.2rem, 6vw, 4.8rem); line-height: 1.02; letter-spacing: -0.04em; }
h2 { margin-top: 0; }
.lead { max-width: 780px; font-size: 1.2rem; color: #c9d1d9; }
.eyebrow { color: var(--accent); font-size: 0.82rem; font-weight: 700; letter-spacing: 0.12em; text-transform: uppercase; }
section { margin-top: 2rem; padding: 1.5rem; border: 1px solid var(--border); border-radius: 12px; background: var(--panel); }
.authority { border-color: #1f6feb; }
.button { display: inline-block; padding: 0.7rem 1rem; border: 1px solid #1f6feb; border-radius: 8px; text-decoration: none; font-weight: 700; }

.format-catalog-intro { border-color: #1f6feb; }
.catalog-count { margin-bottom: 0; color: var(--muted); font-weight: 700; }
.format-domain { background: transparent; border: 0; padding: 0; }
.format-domain > h2 { padding-top: 0.5rem; border-bottom: 1px solid var(--border); }
.format-grid, .lesson-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
}
.format-card {
  display: flex;
  min-height: 185px;
  flex-direction: column;
  gap: 0.75rem;
  padding: 1rem;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--panel);
  color: var(--text);
  text-decoration: none;
  transition: border-color 120ms ease, transform 120ms ease;
}
.format-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.format-card-name { font-size: 1.25rem; font-weight: 800; }
.format-card-purpose { flex: 1; color: #c9d1d9; font-size: 0.94rem; }
.format-badges { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.2rem 0.5rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: #0d1117;
  color: var(--muted);
  font-size: 0.75rem;
  line-height: 1.4;
}
.badge-exe-confirmed, .badge-data-confirmed, .badge-standard, .badge-structural { color: #7ee787; border-color: #238636; }
.badge-high-confidence, .badge-partial, .badge-recognized { color: #d2a8ff; border-color: #8957e5; }
.badge-open, .badge-research-required, .badge-research-only, .badge-runtime-only { color: #e3b341; border-color: #9e6a03; }
.badge-capability-only, .badge-external, .badge-fallback-only, .badge-logical { color: #79c0ff; border-color: #1f6feb; }
.format-status { border-color: #30363d; }
.format-facts { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 0.75rem; margin: 0 0 1rem; }
.format-facts div { padding: 0.8rem; border: 1px solid var(--border); border-radius: 8px; background: #0d1117; }
.format-facts dt { color: var(--muted); font-size: 0.78rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; }
.format-facts dd { margin: 0.2rem 0 0; font-weight: 700; }
.learning-path { border-color: #8957e5; }
.lesson-card { padding: 1rem; border: 1px solid var(--border); border-radius: 10px; background: #0d1117; }
.lesson-card h3 { margin: 0 0 0.5rem; }
.lesson-card p:last-child { margin-bottom: 0; }
.lesson-card span[aria-hidden="true"] { color: var(--muted); padding: 0 0.25rem; }

.lesson-navigation {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  margin: 2rem 0;
  padding: 0.9rem 1rem;
  border: 1px solid #8957e5;
  border-radius: 10px;
  background: #11151c;
}
.lesson-navigation a { font-weight: 700; text-decoration: none; }
.lesson-body {
  margin-top: 2rem;
  padding: clamp(1.25rem, 4vw, 2.25rem);
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--panel);
}
.lesson-body h2 { margin-top: 2.2rem; padding-bottom: 0.35rem; border-bottom: 1px solid var(--border); }
.lesson-body h2:first-child { margin-top: 0; }
.lesson-body h3 { margin-top: 1.7rem; }
.lesson-body p, .lesson-body li { color: #c9d1d9; }
.lesson-body code {
  padding: 0.12rem 0.35rem;
  border: 1px solid var(--border);
  border-radius: 5px;
  background: #0d1117;
  color: #f0f6fc;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.92em;
}
.lesson-body pre {
  overflow-x: auto;
  padding: 1rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: #090c10;
}
.lesson-body pre code { padding: 0; border: 0; background: transparent; }
.lesson-body blockquote { margin: 1.25rem 0; padding: 0.1rem 1rem; border-left: 3px solid #8957e5; color: var(--muted); }
.lesson-body hr { border: 0; border-top: 1px solid var(--border); margin: 2rem 0; }

@media (max-width: 760px) {
  .site-header { align-items: flex-start; flex-direction: column; }
  main { padding-top: 2.5rem; }
  .format-grid, .lesson-grid { grid-template-columns: 1fr; }
  .lesson-navigation { align-items: flex-start; flex-direction: column; }
}