:root {
  --bg: #0d1117;
  --bg-panel: #161b22;
  --border: #30363d;
  --text: #c9d1d9;
  --text-dim: #8b949e;
  --accent: #58a6ff;
  --done: #3fb950;
  --in-progress: #d29922;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
}

#app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.25rem;
  border-bottom: 1px solid var(--border);
  background: var(--bg-panel);
}

#app-header h1 { font-size: 1.1rem; margin: 0; }

#top-nav a {
  color: var(--text-dim);
  text-decoration: none;
  margin-left: 1.25rem;
  font-size: 0.9rem;
}

#top-nav a:hover { color: var(--accent); }

#app-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  min-height: calc(100vh - 3rem);
}

#sidebar {
  border-right: 1px solid var(--border);
  padding: 1rem;
  overflow-y: auto;
  max-height: calc(100vh - 3rem);
}

#sidebar .domain-group { margin-bottom: 1.25rem; }
#sidebar h3 { font-size: 0.85rem; color: var(--text-dim); text-transform: uppercase; margin: 0 0 0.4rem; display: flex; justify-content: space-between; }
#sidebar ul { list-style: none; margin: 0; padding: 0; }
#sidebar li { margin-bottom: 0.2rem; }
#sidebar a { color: var(--text); text-decoration: none; font-size: 0.9rem; }
#sidebar a:hover { color: var(--accent); }

#content {
  padding: 1.5rem 2rem;
  max-width: 860px;
  line-height: 1.6;
}

#content article h2 { border-bottom: 1px solid var(--border); padding-bottom: 0.4rem; }
#content pre { background: var(--bg-panel); padding: 1rem; border-radius: 6px; overflow-x: auto; }
#content code { font-family: "SF Mono", Menlo, monospace; }
#content .mermaid { background: var(--bg-panel); padding: 1rem; border-radius: 6px; }
#content .mermaid svg { max-width: 100%; height: auto; }
#content table { border-collapse: collapse; width: 100%; }
#content th, #content td { border: 1px solid var(--border); padding: 0.4rem 0.6rem; text-align: left; }
#content .coming-soon { color: var(--text-dim); font-style: italic; }
#content .error { color: #f85149; }
#content #mark-done-btn, #content #topic-search { margin-top: 1rem; padding: 0.4rem 0.8rem; background: var(--bg-panel); color: var(--text); border: 1px solid var(--border); border-radius: 4px; }
#content #mark-done-btn:hover { border-color: var(--accent); cursor: pointer; }

.flashcard { background: var(--bg-panel); border: 1px solid var(--border); border-radius: 8px; padding: 1.5rem; max-width: 500px; }
.flashcard .flashcard-face { font-size: 1.1rem; margin-bottom: 1rem; }
.flashcard .hidden { display: none; }
.flashcard button { margin-right: 0.5rem; padding: 0.4rem 0.9rem; border-radius: 4px; border: 1px solid var(--border); background: var(--bg); color: var(--text); cursor: pointer; }
.flashcard .correct-btn { border-color: var(--done); }
.flashcard .wrong-btn { border-color: #f85149; }
.flashcard .queue-count { color: var(--text-dim); font-size: 0.85rem; margin-top: 1rem; }

#content article a { color: var(--accent); }
#content article img { max-width: 100%; height: auto; }
#content article blockquote { margin: 1rem 0; padding: 0.2rem 1rem; border-left: 3px solid var(--border); color: var(--text-dim); }
#content article details > summary { cursor: pointer; font-weight: 600; margin: 0.5rem 0; }

.main-links { list-style: none; padding: 0; margin: 0 0 1rem; }
.main-links a { display: block; padding: 0.15rem 0; font-weight: 600; }
.areas { list-style: none; padding: 0; margin: 0; }
.areas li a { display: flex; justify-content: space-between; gap: 0.5rem; padding: 0.2rem 0.4rem; border-radius: 4px; }
.areas li.active a { background: var(--bg); color: var(--accent); }
.count { color: var(--text-dim); font-size: 0.8rem; }
.badge { display: inline-block; padding: 0 0.45rem; margin-right: 0.3rem; border: 1px solid var(--border); border-radius: 10px; font-size: 0.72rem; color: var(--text-dim); }
.badge.p-P0 { border-color: var(--done); color: var(--done); }
.badge.p-P1 { border-color: var(--in-progress); color: var(--in-progress); }
.hours { color: var(--text-dim); font-size: 0.8rem; }
.topic-list { list-style: none; padding: 0; margin: 0 0 1rem; }
ol.topic-list { list-style: decimal inside; }
.topic-row { display: flex; justify-content: space-between; gap: 1rem; padding: 0.3rem 0; border-bottom: 1px solid var(--border); }
.topic-row a { color: var(--text); text-decoration: none; }
.topic-row a:hover { color: var(--accent); }
.meta { white-space: nowrap; }
.tabs, .chips, .filters { display: flex; flex-wrap: wrap; gap: 0.5rem; margin: 0.8rem 0; align-items: center; }
.tab, .chip, .btn { padding: 0.3rem 0.7rem; border: 1px solid var(--border); border-radius: 6px; color: var(--text); text-decoration: none; background: var(--bg-panel); }
.tab.active, .chip.active { border-color: var(--accent); color: var(--accent); }
.filters select { background: var(--bg-panel); color: var(--text); border: 1px solid var(--border); border-radius: 4px; padding: 0.25rem; }
.area-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 0.8rem; }
.area-card { display: flex; flex-direction: column; gap: 0.4rem; padding: 0.8rem; background: var(--bg-panel); border: 1px solid var(--border); border-radius: 8px; color: var(--text); text-decoration: none; }
.area-card:hover { border-color: var(--accent); }
.bar { display: block; height: 6px; background: var(--border); border-radius: 3px; overflow: hidden; min-width: 80px; }
.bar-fill { display: block; height: 100%; background: var(--done); }
.topic-head { margin-bottom: 1rem; }
.topic-head .crumbs, .topic-head .badges { margin-bottom: 0.4rem; color: var(--text-dim); }
.prevnext { display: flex; justify-content: space-between; gap: 1rem; font-size: 0.9rem; }
.related { margin-top: 2rem; border-top: 1px solid var(--border); padding-top: 0.5rem; }
.collection { margin: 0.5rem 0; background: var(--bg-panel); border: 1px solid var(--border); border-radius: 6px; padding: 0.5rem 0.8rem; }
.collection summary { cursor: pointer; font-weight: 600; }
#search-open { background: var(--bg-panel); color: var(--text-dim); border: 1px solid var(--border); border-radius: 6px; padding: 0.25rem 0.6rem; cursor: pointer; margin-right: 1rem; }
#search-open kbd { border: 1px solid var(--border); border-radius: 3px; padding: 0 0.3rem; }
#search-modal { position: fixed; inset: 0; background: rgba(0,0,0,0.6); display: flex; justify-content: center; align-items: flex-start; padding-top: 8vh; z-index: 50; }
#search-box { width: min(760px, 92vw); max-height: 80vh; overflow: auto; background: var(--bg-panel); border: 1px solid var(--border); border-radius: 10px; padding: 1rem; }
#search-box input[type=search] { width: 100%; box-sizing: border-box; padding: 0.6rem; font-size: 1rem; background: var(--bg); color: var(--text); border: 1px solid var(--border); border-radius: 6px; }
.search-result { padding: 0.6rem 0; border-bottom: 1px solid var(--border); }
.search-result a { color: var(--accent); text-decoration: none; font-weight: 600; }
.search-result mark { background: #3b2f00; color: #ffd866; }

#sidebar .topic-nav h3 { margin-top: 1.2rem; }
#content .topic-head a, #content .related a, #content .prevnext a, #content .continue a, #content table a { color: var(--accent); }
.search-result .meta { color: var(--text-dim); font-size: 0.8rem; margin: 0.15rem 0; }
.search-result p { margin: 0.3rem 0 0; }
@media (max-width: 800px) {
  #app-layout { grid-template-columns: 1fr; }
  #sidebar { border-right: 0; border-bottom: 1px solid var(--border); max-height: 38vh; }
  #top-nav a { display: none; }
  #app-header h1 { font-size: 1rem; }
  #content { padding: 1rem; }
  .topic-row { flex-direction: column; gap: 0.2rem; }
}