.overview-intro { margin-bottom: 24px; }
.overview-stats { display: flex; flex-wrap: wrap; gap: 12px 28px; margin-top: 24px; color: var(--muted); font-size: 14px; }
.overview-stats strong { margin-right: 4px; color: var(--ink); font-size: 20px; font-weight: 500; }
.overview-reading-note { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px 24px; margin-bottom: 28px; color: var(--muted); font-size: 14px; }
.overview-reading-note p { margin: 0; }
.overview-reading-note a { color: var(--green); text-decoration: underline; text-underline-offset: 4px; }
.overview-controls { display: grid; grid-template-columns: minmax(0, 1fr) 220px auto; align-items: end; gap: 18px; padding: 24px; border: 1px solid var(--line); border-radius: 4px; background: var(--paper); }
.overview-controls label { display: grid; gap: 7px; color: var(--muted); font-size: 13px; }
.overview-controls input, .overview-controls select { width: 100%; min-width: 0; min-height: 44px; padding: 10px 12px; border: 1px solid #d6d9d1; border-radius: 3px; color: var(--ink); background: var(--white); font-size: 14px; }
.overview-controls input::placeholder { color: #7b8075; }
.overview-toolbar { grid-column: 1 / -1; display: flex; flex-wrap: wrap; gap: 10px 22px; align-items: center; }
.overview-toolbar p { margin: 0 auto 0 0; color: var(--muted); font-size: 13px; }
.overview-toolbar button { padding: 3px 0; border: 0; background: transparent; color: var(--green); font-size: 13px; text-decoration: underline; text-underline-offset: 4px; }
.overview-legend { padding: 12px 0; margin-top: 10px; background: none; font-size: 13px; }
.overview-legend summary { color: var(--muted); }
.overview-legend p { max-width: 800px; margin: 10px 0 0; color: var(--muted); }
.overview-legend strong { color: var(--green); font-weight: 500; }
.overview-part-links { display: flex; flex-wrap: wrap; gap: 8px; margin: 22px 0 28px; }
.overview-part-links a { display: inline-block; padding: 5px 11px; border: 1px solid var(--line); border-radius: 3px; color: var(--muted); font-size: 12px; }
.overview-part-links a:hover, .overview-part-links a:focus-visible { color: var(--green); border-color: #aeb7a8; background: var(--green-soft); }
.overview-catalog { display: grid; gap: 12px; }
.overview-catalog details { margin: 0; padding: 0; border-radius: 4px; background: var(--white); }
.overview-part { border: 1px solid var(--line); }
.overview-catalog summary { display: flex; align-items: center; gap: 18px; color: var(--ink); list-style: none; }
.overview-catalog summary::-webkit-details-marker { display: none; }
.overview-catalog summary::after { content: "+"; flex: 0 0 15px; margin-left: auto; color: var(--green); font-size: 21px; font-weight: 400; text-align: center; }
.overview-catalog details[open] > summary::after { content: "−"; }
.overview-catalog summary:hover { background: var(--paper); }
.overview-part > summary { padding: 21px 23px; }
.overview-part[open] > summary { background: var(--green-soft); }
.overview-part-number { flex: 0 0 68px; color: var(--green); font-size: 12px; font-weight: 500; letter-spacing: .03em; }
.overview-item-title { min-width: 0; flex: 1; }
.overview-title-zh, .overview-title-en { display: block; overflow-wrap: anywhere; }
.overview-title-zh { font-size: 17px; font-weight: 500; }
.overview-title-en { margin-top: 4px; color: var(--muted); font-size: 13px; font-weight: 400; line-height: 1.5; }
.overview-item-count { flex: 0 0 auto; color: var(--muted); font-size: 12px; font-weight: 400; white-space: nowrap; }
.overview-units { padding: 8px 23px 16px; }
.overview-unit + .overview-unit { border-top: 1px solid var(--line); border-radius: 0; }
.overview-unit > summary { padding: 17px 0; }
.overview-unit .overview-title-zh { font-size: 15px; }
.overview-item-number { flex: 0 0 68px; color: var(--muted); font-size: 12px; font-weight: 400; }
.overview-lessons { margin-left: 86px; }
.overview-lesson { border-top: 1px solid var(--line); border-radius: 0 !important; }
.overview-lesson > summary { padding: 16px 0; gap: 14px; }
.overview-lesson > summary .overview-title-zh { font-size: 14px; font-weight: 400; }
.overview-lesson > summary .overview-title-en { font-size: 12px; }
.overview-lesson > summary .overview-item-number { flex-basis: 82px; font-size: 11px; }
.overview-level { flex: 0 0 auto; border-radius: 3px; padding: 2px 6px; color: #756941; background: var(--yellow-soft); font-size: 11px; font-weight: 400; white-space: nowrap; }
.overview-lesson-reading { margin: 0 0 14px; font-size: 13px; }
.overview-read { display: inline-block; padding: 8px 14px; border: 1px solid #b7c0b0; border-radius: 4px; color: var(--green); background: var(--green-soft); }
.overview-read:hover, .overview-read:focus-visible { border-color: var(--green); text-decoration: underline; text-underline-offset: 4px; }
.overview-pending { color: var(--muted); font-size: 12px; }
.overview-knowledge a { min-width: 0; }
.overview-knowledge a:hover .overview-title-zh, .overview-knowledge a:focus-visible .overview-title-zh { color: var(--green); text-decoration: underline; text-underline-offset: 4px; }
.overview-knowledge { margin: 0 0 16px; padding: 4px 18px; list-style: none; background: var(--paper); border-radius: 4px; }
.overview-knowledge li { display: grid; grid-template-columns: 125px minmax(0, 1fr); gap: 15px; padding: 12px 0; }
.overview-knowledge li + li { border-top: 1px solid var(--line); }
.overview-knowledge-id { color: var(--muted); font-size: 10px; line-height: 2.2; font-variant-numeric: tabular-nums; }
.overview-knowledge .overview-title-zh { font-size: 13px; font-weight: 400; }
.overview-knowledge .overview-title-en { font-size: 12px; }
.overview-knowledge li:target { background: var(--yellow-soft); }
.overview-empty, .overview-noscript { padding: 22px; color: var(--muted); background: var(--yellow-soft); border-radius: 4px; font-size: 14px; }
.overview-back-top { display: inline-block; margin-top: 28px; color: var(--green); font-size: 13px; }
.overview-catalog [id] { scroll-margin-top: 120px; }
@media (max-width: 760px) {
  .overview-controls { grid-template-columns: minmax(0, 1fr) auto; padding: 18px; gap: 14px; }
  .overview-search { grid-column: 1 / -1; }
  .overview-toolbar p { flex: 0 0 100%; }
  .overview-stats { gap: 10px 18px; }
  .overview-part > summary { display: grid; grid-template-columns: 54px minmax(0, 1fr) 15px; gap: 8px 12px; padding: 18px 15px; }
  .overview-part-number { flex-basis: 54px; font-size: 10px; }
  .overview-part > summary .overview-item-title { grid-column: 2; grid-row: 1; }
  .overview-part > summary .overview-item-count { grid-column: 2; grid-row: 2; }
  .overview-part > summary::after { grid-column: 3; grid-row: 1; margin: 0; }
  .overview-part > summary .overview-title-zh { font-size: 16px; }
  .overview-units { padding: 4px 15px 12px; }
  .overview-unit > summary { gap: 12px; }
  .overview-item-number { flex-basis: 50px; font-size: 11px; }
  .overview-lessons { margin-left: 0; }
  .overview-lesson > summary { flex-wrap: wrap; gap: 8px 12px; }
  .overview-lesson > summary .overview-item-number { flex-basis: 100%; }
  .overview-level { font-size: 10px; }
  .overview-knowledge { padding: 2px 12px; }
  .overview-knowledge li { grid-template-columns: minmax(0, 1fr); gap: 3px; }
  .overview-catalog [id] { scroll-margin-top: 150px; }
}
@media print {
  .overview-controls, .overview-part-links, .overview-back-top { display: none; }
  .overview-catalog details > :not(summary) { display: block !important; }
  .overview-catalog summary::after { display: none; }
}