:root {
  --bg: #0e1116;
  --panel: #161b22;
  --panel-2: #1f2630;
  --border: #2a313c;
  --text: #e6edf3;
  --muted: #8b949e;
  --accent: #58a6ff;
  --green: #3fb950;
  --amber: #d29922;
  --red: #f85149;
  --grey: #6e7681;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; background: var(--bg); color: var(--text); font-family: -apple-system, Segoe UI, Inter, system-ui, sans-serif; line-height: 1.5; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
code { background: var(--panel-2); padding: 1px 6px; border-radius: 4px; font-size: 0.9em; }
header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 28px; border-bottom: 1px solid var(--border); background: var(--panel);
  position: sticky; top: 0; z-index: 10;
}
.brand a { color: var(--text); font-weight: 600; font-size: 1.1rem; }
nav a {
  margin-left: 22px; color: var(--muted); font-weight: 500;
}
nav a.active, nav a:hover { color: var(--text); text-decoration: none; }
main {
  max-width: 1200px; margin: 0 auto; padding: 28px;
}
footer {
  padding: 18px 28px; border-top: 1px solid var(--border); color: var(--muted); font-size: 0.85rem; margin-top: 60px;
}
h1 { margin-top: 0; font-size: 1.6rem; }
h2 { margin-top: 2rem; border-bottom: 1px solid var(--border); padding-bottom: 6px; }
.loading, .empty { color: var(--muted); font-style: italic; }

/* Flow map */
.flow-scroll { overflow-x: auto; padding-bottom: 12px; }
.flow-row { display: flex; gap: 18px; align-items: stretch; min-width: max-content; }
.stage-card {
  background: var(--panel); border: 1px solid var(--border); border-radius: 10px;
  padding: 16px 18px; min-width: 260px; max-width: 300px;
  display: flex; flex-direction: column; gap: 8px;
  cursor: pointer; transition: border-color 0.15s, transform 0.15s;
}
.stage-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.stage-key { color: var(--muted); font-size: 0.8rem; font-weight: 600; letter-spacing: 0.05em; }
.stage-title { font-weight: 600; font-size: 1.05rem; }
.stage-desc { color: var(--muted); font-size: 0.88rem; }
.stage-arrow { display: flex; align-items: center; color: var(--border); font-size: 1.4rem; }

.badge {
  display: inline-block; padding: 2px 10px; border-radius: 999px;
  font-size: 0.72rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.04em;
}
.badge.green { background: rgba(63,185,80,0.15); color: var(--green); }
.badge.amber { background: rgba(210,153,34,0.15); color: var(--amber); }
.badge.red   { background: rgba(248,81,73,0.15);  color: var(--red); }
.badge.grey  { background: rgba(110,118,129,0.15); color: var(--grey); }

/* Grid cards */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 18px; }
.card {
  background: var(--panel); border: 1px solid var(--border); border-radius: 10px;
  padding: 16px 18px; display: flex; flex-direction: column; gap: 8px;
}
.card .key { color: var(--muted); font-size: 0.75rem; font-weight: 600; }
.card .title { font-weight: 600; font-size: 1rem; }
.card .desc { color: var(--muted); font-size: 0.88rem; flex: 1; }
.card .tags { display: flex; flex-wrap: wrap; gap: 6px; }
.tag { background: var(--panel-2); color: var(--muted); padding: 2px 8px; border-radius: 6px; font-size: 0.72rem; }

/* Stage detail */
.stage-detail { background: var(--panel); border: 1px solid var(--border); border-radius: 10px; padding: 24px 28px; }
.stage-detail h1 { margin-bottom: 4px; }
.stage-detail .meta { color: var(--muted); margin-bottom: 20px; font-size: 0.9rem; }
.stage-detail .content { margin-top: 20px; }
.stage-detail .content h1, .stage-detail .content h2, .stage-detail .content h3 { border: none; }
.stage-detail .content p, .stage-detail .content li { color: var(--text); }
.stage-detail .content pre { background: var(--panel-2); padding: 12px; border-radius: 6px; overflow-x: auto; }

.back { color: var(--muted); font-size: 0.9rem; display: inline-block; margin-bottom: 16px; }
.back:hover { color: var(--accent); }

/* Filter bar */
.filter-bar { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 18px; }
.filter-bar select, .filter-bar input {
  background: var(--panel); color: var(--text); border: 1px solid var(--border);
  border-radius: 6px; padding: 6px 10px; font-size: 0.9rem;
}

/* Friction list */
.friction-item {
  background: var(--panel); border: 1px solid var(--border); border-left: 4px solid var(--grey);
  border-radius: 8px; padding: 14px 18px; margin-bottom: 12px;
}
.friction-item.high { border-left-color: var(--red); }
.friction-item.medium { border-left-color: var(--amber); }
.friction-item.low { border-left-color: var(--green); }
.friction-head { display: flex; justify-content: space-between; align-items: start; gap: 16px; }
.friction-title { font-weight: 600; margin-bottom: 4px; }
.friction-meta { color: var(--muted); font-size: 0.8rem; }
.friction-body { color: var(--muted); font-size: 0.9rem; margin-top: 8px; }

@media (max-width: 640px) {
  header { padding: 12px 16px; flex-wrap: wrap; }
  nav a { margin-left: 0; margin-right: 14px; font-size: 0.9rem; }
  main { padding: 18px 16px; }
}