/* Sticky chapter tab bar, prev/next links and the full-source panel. */

.tabs {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--bg, #0a0a0f);
  border-bottom: 1px solid var(--line, #23232f);
  padding: 10px 24px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: center;
}
.tabs a {
  font-family: var(--mono, ui-monospace, monospace);
  font-size: 13px;
  color: var(--muted, #8a8a9c);
  text-decoration: none;
  padding: 6px 11px;
  border: 1px solid transparent;
  border-radius: 8px;
}
.tabs a:hover { color: var(--ink, #e7e7ef); border-color: var(--line, #23232f); }
.tabs a.active { color: var(--accent, #7cc4ff); border-color: var(--line, #23232f); background: var(--panel, #13131c); }

main section.chapter { display: none; margin-top: 36px; }
main section.chapter.active { display: block; }

.chapter-nav { display: flex; justify-content: space-between; margin-top: 48px; gap: 20px; }
.chapter-nav a { color: var(--accent, #7cc4ff); text-decoration: none; font-size: 15px; }
.chapter-nav a:hover { text-decoration: underline; }

details.source {
  margin: 26px 0;
  border: 1px solid var(--line, #23232f);
  border-radius: 10px;
  background: var(--panel, #13131c);
}
details.source summary {
  cursor: pointer;
  padding: 10px 14px;
  font-family: var(--mono, ui-monospace, monospace);
  font-size: 12px;
  color: var(--muted, #8a8a9c);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  list-style: none;
}
details.source summary::before { content: '▸ '; }
details.source[open] summary::before { content: '▾ '; }
.src-files { display: flex; flex-wrap: wrap; gap: 8px; padding: 2px 14px 12px; }
.src-files button {
  background: none;
  border: 1px solid var(--line, #23232f);
  border-radius: 7px;
  color: var(--muted, #8a8a9c);
  font-family: var(--mono, ui-monospace, monospace);
  font-size: 12.5px;
  padding: 4px 10px;
  cursor: pointer;
}
.src-files button:hover { color: var(--ink, #e7e7ef); }
.src-files button.active { color: var(--accent, #7cc4ff); border-color: var(--line, #23232f); }
.src-view {
  margin: 0;
  border-top: 1px solid var(--line, #23232f);
  padding: 14px 16px;
  font-family: var(--mono, ui-monospace, monospace);
  font-size: 13px;
  line-height: 1.6;
  color: var(--ink, #e7e7ef);
  overflow: auto;
  max-height: 480px;
  white-space: pre;
}