/* ============================================================================ */
/* Table of contents ("line"): sticky rail aligned with the first body line.    */
/* Behaviour in src/scripts/layout/toc.ts.                                      */
/* ============================================================================ */

.table-of-contents {
  grid-column: toc;
  grid-row: 1;
  justify-self: end;
  width: min(var(--layout-toc-width), 100%);
  position: sticky;
  top: var(--layout-sticky-top);
  /* matches the cap height of a first-line h2 */
  margin-top: 3px;
  z-index: 5;
  font-size: 13px;
  transition: opacity .2s ease;
}

.table-of-contents[hidden],
.toc-topbar[hidden] {
  display: none !important;
}

.table-of-contents.is-occluded {
  opacity: 0;
  pointer-events: none;
}

.table-of-contents ol {
  list-style: none;
  margin: 0;
  padding: 0;
}

.table-of-contents a {
  display: block;
  color: var(--muted-color);
  text-decoration: none;
  border: 0;
}

.table-of-contents a:hover {
  color: var(--text-color);
}

.table-of-contents a[aria-current] {
  color: var(--text-color);
  font-weight: 600;
}

.table-of-contents a:focus-visible,
.toc-topbar button:focus-visible {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
  border-radius: 3px;
}

.toc-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 8px;
  margin: 0 0 10px;
}

.toc-title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--muted-color);
}

.toc-meta {
  font-size: 11px;
  color: var(--muted-color);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

/* Reading time appears once the TOC is stuck (space stays reserved, no layout shift) */
.table-of-contents .toc-meta {
  opacity: 0;
  visibility: hidden;
  transform: translateY(-3px);
  transition: opacity .2s ease, transform .2s ease, visibility 0s linear .2s;
}

.table-of-contents.is-stuck .toc-meta,
.toc-open .table-of-contents .toc-meta {
  opacity: 1;
  visibility: visible;
  transform: none;
  transition: opacity .2s ease, transform .2s ease, visibility 0s;
}

/* Internal scroll when the outline is taller than the viewport */
.toc-scroll {
  max-height: calc(100vh - var(--layout-sticky-top) - 88px);
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: none;
  padding: 6px 4px 10px 0;
  -webkit-mask-image: linear-gradient(transparent, #000 8px, #000 calc(100% - 14px), transparent);
  mask-image: linear-gradient(transparent, #000 8px, #000 calc(100% - 14px), transparent);
}

.toc-scroll::-webkit-scrollbar {
  display: none;
}

.toc-list {
  position: relative;
  padding-left: 14px;
}

.toc-track,
.toc-fill,
.toc-indicator {
  position: absolute;
  left: 0;
  top: 0;
}

.toc-track {
  bottom: 0;
  width: 1px;
  background: var(--border-color);
}

.toc-fill {
  width: 1px;
  height: 0;
  background: color-mix(in srgb, var(--primary-color) 70%, transparent);
}

.toc-indicator {
  left: -1px;
  width: 3px;
  height: 0;
  border-radius: 3px;
  background: var(--primary-color);
  opacity: 0;
}

.table-of-contents.is-ready .toc-indicator {
  opacity: 1;
  transition: transform .2s cubic-bezier(.2, .7, .2, 1), height .2s cubic-bezier(.2, .7, .2, 1);
}

.toc-sec > a {
  padding: 4px 0;
  line-height: 1.35;
  transition: color .2s;
}

.toc-sec.is-read > a {
  color: color-mix(in srgb, var(--text-color) 45%, transparent);
}

/* Sub-headings: expanded by default, active section only with data-toc-expanded="false" */
.toc-sub {
  display: grid;
  grid-template-rows: 0fr;
  visibility: hidden;
  transition: grid-template-rows .22s ease, visibility 0s linear .22s;
}

.toc-sub > ol {
  overflow: hidden;
  min-height: 0;
}

.toc-sec.is-open > .toc-sub,
.table-of-contents:not([data-toc-expanded="false"]) .toc-sub {
  grid-template-rows: 1fr;
  visibility: visible;
  transition: grid-template-rows .22s ease, visibility 0s;
}

.toc-sub a {
  padding: 3px 0 3px 12px;
  font-size: 12.5px;
  line-height: 1.35;
}

.toc-sub li:last-child a {
  padding-bottom: 7px;
}

/* ---------------------------------------------------------------------------- */
/* Below the collapse breakpoint: slim sticky bar with the current section,     */
/* opening the same nav as a drawer                                             */
/* ---------------------------------------------------------------------------- */

.toc-topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--layout-topbar-height);
  z-index: var(--z-modal);
  display: none;
  align-items: center;
  gap: 12px;
  padding: 0 14px;
  font-size: 14px;
  color: var(--text-color);
  background: color-mix(in srgb, var(--page-bg) 88%, transparent);
  -webkit-backdrop-filter: saturate(1.4) blur(8px);
  backdrop-filter: saturate(1.4) blur(8px);
  border-bottom: 1px solid var(--border-color);
  transform: translateY(-100%);
  transition: transform .25s ease;
}

.toc-topbar-visible .toc-topbar {
  transform: none;
}

.toc-topbar__btn {
  display: flex;
  align-items: center;
  gap: 6px;
  flex: none;
  border: 1px solid var(--border-color);
  background: var(--page-bg);
  border-radius: 8px;
  padding: 4px 10px;
  font: inherit;
  font-size: 13px;
  color: var(--text-color);
  cursor: pointer;
}

.toc-topbar__crumb {
  flex: 1;
  min-width: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.toc-topbar__sec {
  font-weight: 600;
}

.toc-topbar__sub {
  color: var(--muted-color);
}

.toc-topbar__sub:not(:empty)::before {
  content: " / ";
}

.toc-topbar__meta {
  flex: none;
  color: var(--muted-color);
  font-size: 12px;
  font-variant-numeric: tabular-nums;
}

.toc-topbar__progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
}

.toc-topbar__progress i {
  display: block;
  height: 100%;
  background: var(--primary-color);
  transform-origin: left;
  transform: scaleX(0);
}

.toc-backdrop {
  position: fixed;
  inset: 0;
  z-index: var(--z-modal);
  display: none;
  background: rgba(0, 0, 0, .25);
}

[data-theme="dark"] .toc-backdrop {
  background: rgba(0, 0, 0, .55);
}

@media (--bp-content-collapse) {
  .table-of-contents {
    display: none;
  }

  .toc-topbar {
    display: flex;
  }

  .toc-open .toc-backdrop {
    display: block;
  }

  .toc-open .table-of-contents {
    display: block;
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: min(300px, 85vw);
    margin: 0;
    padding: 72px 24px;
    overflow: auto;
    z-index: calc(var(--z-modal) + 1);
    background: var(--page-bg);
    border-right: 1px solid var(--border-color);
    box-shadow: 4px 0 24px rgba(0, 0, 0, .12);
  }

  .toc-open .toc-scroll {
    max-height: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  .table-of-contents,
  .table-of-contents *,
  .toc-topbar,
  .toc-topbar * {
    transition: none !important;
  }
}

@media print {
  .table-of-contents,
  .toc-topbar,
  .toc-backdrop {
    display: none !important;
  }
}