:root {
  color-scheme: light dark;
  --bg: #0f1115;
  --panel: #171a21;
  --text: #e6e6e6;
  --muted: #9aa0aa;
  --accent: #4c8dff;
  --added: #3fb950;
  --removed: #f85149;
  --border: #2a2f3a;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
}

header, main, footer {
  max-width: 78rem;
  margin: 0 auto;
  padding: 1rem 1.25rem;
}

h1 { margin: 0; font-size: 1.6rem; }
h2 { margin: 0.25rem 0 0; font-size: 1.25rem; }
h3 { margin: 0 0 0.6rem; font-size: 1rem; }
.tagline, .description, .meta, footer p { color: var(--muted); }
.meta { font-size: 0.85rem; }
.count { color: var(--muted); font-size: 0.8rem; font-weight: 400; }
.empty { color: var(--muted); font-style: italic; }

.tabs {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  padding: 0 1.25rem;
  max-width: 78rem;
  margin: 1rem auto 0;
}

.tab {
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.35rem 0.9rem;
  cursor: pointer;
  font-size: 0.9rem;
}
.tab[aria-selected="true"] {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.panels {
  display: grid;
  grid-template-columns: minmax(240px, 340px) 1fr;
  grid-template-areas:
    "documents viewer"
    "history   diff";
  gap: 1rem;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.9rem;
  min-width: 0;
}

#panel-documents { grid-area: documents; }
#panel-viewer { grid-area: viewer; }
#panel-history { grid-area: history; }
#panel-diff { grid-area: diff; }

#doc-filter {
  width: 100%;
  margin-bottom: 0.6rem;
  padding: 0.4rem 0.6rem;
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  font: inherit;
}

.document-list, .snapshot-list, .patch-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  max-height: 26rem;
  overflow-y: auto;
}

.document-list li button {
  display: block;
  width: 100%;
  text-align: left;
  background: transparent;
  border: 1px solid transparent;
  border-radius: 6px;
  color: var(--text);
  padding: 0.35rem 0.5rem;
  cursor: pointer;
  font: inherit;
  font-size: 0.85rem;
}
.document-list li button:hover { border-color: var(--border); }
.document-list li button.selected { border-color: var(--accent); background: rgba(76, 141, 255, 0.12); }
.document-list .doc-title { display: block; }
.document-list .doc-category { display: block; color: var(--muted); font-size: 0.72rem; }

.snapshot-row {
  display: flex;
  gap: 0.8rem;
  width: 100%;
  text-align: left;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.5rem 0.7rem;
  color: var(--text);
  cursor: pointer;
  font: inherit;
  font-size: 0.85rem;
}
.snapshot-row:hover { border-color: var(--accent); }
.snapshot-row .date, .snapshot-row .changes { color: var(--muted); font-size: 0.78rem; }
.snapshot-row .changes { margin-left: auto; }

pre.content, pre.diff {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.75rem;
  overflow: auto;
  max-height: 34rem;
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 0.78rem;
  line-height: 1.45;
  white-space: pre-wrap;
  word-break: break-word;
}

pre.diff .add { color: var(--added); }
pre.diff .del { color: var(--removed); }
pre.diff .hunk { color: var(--accent); }
pre.diff .meta-line { color: var(--muted); }

.timeline { display: flex; flex-wrap: wrap; gap: 0.4rem; margin: 0.5rem 0 0.8rem; }
.timeline button {
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.15rem 0.55rem;
  font: inherit;
  font-size: 0.75rem;
  cursor: pointer;
}
.timeline button[aria-current="true"] { border-color: var(--accent); color: var(--accent); }
.timeline button:disabled { opacity: 0.4; cursor: not-allowed; }

.patch-list { max-height: 30rem; }
.patch-list > li { margin-bottom: 1rem; }
.patch-header { display: flex; gap: 0.5rem; align-items: center; margin-bottom: 0.3rem; }
.patch-path { font-family: ui-monospace, monospace; font-size: 0.8rem; }
.patch-change { font-size: 0.7rem; padding: 0.05rem 0.45rem; border-radius: 999px; border: 1px solid var(--border); }

@media (max-width: 900px) {
  .panels { grid-template-columns: 1fr; grid-template-areas: "documents" "viewer" "history" "diff"; }
}