.page-features {
  --board-tick: 1;
  display: block;
  background: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: var(--leading-body);
}

.page-features .board-stack {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--space-4);
  box-sizing: border-box;
}

.page-features .board-kicker {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-primary);
}

/* ---------- 面包屑 ---------- */
.page-features .board-crumb {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  max-width: var(--container);
  margin: 0 auto;
  padding: var(--space-6) var(--space-4) 0;
  box-sizing: border-box;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.page-features .board-crumb a {
  color: var(--color-accent);
  text-decoration: none;
  border-bottom: var(--border-thin) solid currentColor;
}

.page-features .board-crumb a:hover,
.page-features .board-crumb a:focus-visible {
  color: var(--color-focus);
}

/* ---------- 首屏框景 ---------- */
.page-features .board-hero {
  padding: var(--space-4) var(--space-4) var(--section-y);
  box-sizing: border-box;
}

.page-features .board-hero__frame {
  position: relative;
  max-width: var(--container);
  margin: 0 auto;
  padding: var(--space-6) var(--space-4) var(--space-6);
  box-sizing: border-box;
  border: var(--border-thin) solid var(--color-line);
  background: var(--color-surface);
}

.page-features .board-hero__frame::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: var(--space-2);
  background-image: repeating-linear-gradient(
    90deg,
    var(--color-line) 0 var(--border-thin),
    transparent var(--border-thin) var(--space-2)
  );
  opacity: 0.9;
}

.page-features .board-hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-6);
}

.page-features .board-hero__title {
  margin: var(--space-3) 0 0;
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.page-features .board-hero__lede {
  margin: var(--space-4) 0 0;
  max-width: var(--measure);
  font-size: var(--text-base);
  color: var(--color-ink-soft);
}

.page-features .board-hero__side {
  position: relative;
  padding-left: var(--space-4);
  border-left: var(--border-thin) solid var(--color-line);
}

.page-features .board-hero__side::after {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: var(--space-1);
  background-image: repeating-linear-gradient(
    180deg,
    var(--color-primary) 0 var(--border-thin),
    transparent var(--border-thin) var(--space-2)
  );
  opacity: 0.7;
}

.page-features .board-hero__media {
  max-width: 100%;
}

/* ---------- 三个数字 ---------- */
.page-features .board-hero__figures {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-3);
  margin-top: var(--space-6);
  padding-top: var(--space-4);
  border-top: var(--border-thin) solid var(--color-line);
}

.page-features .fig {
  position: relative;
  padding-left: var(--space-3);
  border-left: var(--border-thin) solid var(--color-line);
}

.page-features .fig:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: var(--space-1);
}

.page-features .fig__value {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 1;
  font-variant-numeric: tabular-nums;
  color: var(--color-ink);
}

.page-features .fig__unit {
  display: block;
  margin-top: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-primary);
}

.page-features .fig__note {
  display: block;
  margin-top: var(--space-2);
  font-size: var(--text-sm);
  line-height: 1.65;
  color: var(--color-ink-soft);
}

/* ---------- 分组刻度与错位 ---------- */
.page-features .board-deck {
  padding: 0 0 var(--section-y);
}

.page-features .board {
  position: relative;
  border-top: var(--border-thin) solid var(--color-line);
}

.page-features .board--a { --board-tick: 1.6; }
.page-features .board--b { --board-tick: 2.2; }
.page-features .board--c { --board-tick: 3; }
.page-features .board--d { --board-tick: 4; }

.page-features .board__summary {
  position: relative;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: var(--space-2) var(--space-3);
  align-items: baseline;
  padding: var(--space-4) 0 var(--space-3);
  cursor: pointer;
  list-style: none;
}

.page-features .board__summary::-webkit-details-marker {
  display: none;
}

.page-features .board__summary::marker {
  content: "";
}

.page-features .board__summary::before {
  content: "";
  position: absolute;
  left: calc(var(--space-3) * -1);
  top: var(--space-4);
  width: var(--border-thin);
  height: calc(var(--space-3) * var(--board-tick));
  background: var(--color-primary);
  transform-origin: top center;
  transition: transform 200ms ease-out;
}

.page-features .board__summary:hover::before,
.page-features .board__summary:focus-visible::before {
  transform: scaleY(1.4);
}

.page-features .board__summary:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: var(--space-1);
}

.page-features .board__index {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-primary);
}

.page-features .board__title {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.page-features .board__hint {
  display: none;
}

.page-features .board__panel {
  padding-bottom: var(--space-6);
}

.page-features .board__lead {
  margin: 0 0 var(--space-3);
  max-width: var(--measure);
  font-size: var(--text-base);
  color: var(--color-ink-soft);
}

.page-features .board__list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-features .entry {
  border-top: var(--border-thin) solid var(--color-line);
  padding: var(--space-3) 0 var(--space-4);
}

.page-features .entry__title {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  color: var(--color-ink);
}

.page-features .entry__text {
  margin: var(--space-2) 0 0;
  max-width: var(--measure);
  color: var(--color-ink-soft);
}

.page-features .spec {
  margin: var(--space-3) 0 0;
  padding: 0;
}

.page-features .spec__row {
  display: grid;
  grid-template-columns: minmax(6em, 1fr) minmax(0, 2.2fr);
  gap: var(--space-2);
  align-items: baseline;
  padding: var(--space-1) 0;
  border-top: var(--border-thin) solid var(--color-line);
}

.page-features .spec__key {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.page-features .spec__val {
  margin: 0;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-ink-soft);
}

.page-features .board__media {
  margin: 0 0 var(--space-4);
  background: var(--color-surface-alt);
}

.page-features .board__media--square {
  margin: var(--space-4) 0 0;
  max-width: var(--space-8);
  max-width: none;
}

.page-features .board__out {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  margin-top: var(--space-3);
  padding-bottom: var(--space-1);
  font-size: var(--text-sm);
  color: var(--color-accent);
  text-decoration: none;
  border-bottom: var(--border-thin) solid currentColor;
  transition: color 200ms ease-out;
}

.page-features .board__out:hover,
.page-features .board__out:focus-visible {
  color: var(--color-focus);
}

/* ---------- 图片 ---------- */
.page-features .media {
  display: block;
  overflow: hidden;
}

.page-features .media img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
}

/* ---------- 口径表 ---------- */
.page-features .board-table {
  padding: 0 0 var(--section-y);
}

.page-features .board-table__title {
  margin: var(--space-2) 0 0;
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.page-features .board-table__lead {
  margin: var(--space-3) 0 0;
  max-width: var(--measure);
  color: var(--color-ink-soft);
}

.page-features .board-table__scroll {
  margin-top: var(--space-4);
  overflow-x: auto;
  border-top: var(--border-thin) solid var(--color-line);
  border-bottom: var(--border-thin) solid var(--color-line);
  -webkit-overflow-scrolling: touch;
}

.page-features .board-table__grid {
  width: 100%;
  min-width: 640px;
  border-collapse: collapse;
  font-size: var(--text-sm);
}

.page-features .board-table__grid th,
.page-features .board-table__grid td {
  text-align: left;
  padding: var(--space-2) var(--space-3) var(--space-2) 0;
  border-bottom: var(--border-thin) solid var(--color-line);
  vertical-align: top;
  font-weight: var(--weight-body);
}

.page-features .board-table__grid thead th {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  border-bottom: var(--border-thin) solid var(--color-ink-muted);
  white-space: nowrap;
}

.page-features .board-table__grid tbody th {
  position: sticky;
  left: 0;
  white-space: nowrap;
  color: var(--color-ink);
  background: var(--color-surface);
  box-shadow: var(--border-thin) 0 0 var(--color-line);
}

.page-features .board-table__grid tbody td {
  color: var(--color-ink-soft);
  font-variant-numeric: tabular-nums;
}

.page-features .board-table__grid tbody tr:nth-child(even) th,
.page-features .board-table__grid tbody tr:nth-child(even) td {
  background: var(--color-surface-deep);
}

.page-features .board-table__grid tbody tr:last-child th,
.page-features .board-table__grid tbody tr:last-child td {
  border-bottom: 0;
}

/* ---------- 出口对比带 ---------- */
.page-features .board-exit {
  padding: var(--space-8) var(--space-4);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.page-features .board-exit__inner {
  max-width: var(--container);
  margin: 0 auto;
}

.page-features .board-exit__kicker {
  color: var(--color-contrast-accent);
}

.page-features .board-exit__title {
  margin: var(--space-3) 0 var(--space-6);
  max-width: 22ch;
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}

.page-features .board-exit__links {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.page-features .board-exit__links a {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-3);
  padding: var(--space-3) 0;
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-contrast-accent);
  text-decoration: none;
}

.page-features .board-exit__links a:hover,
.page-features .board-exit__links a:focus-visible {
  text-decoration: underline;
}

/* ---------- 平板 ---------- */
@media (min-width: 720px) {
  .page-features .board-hero__figures {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: var(--space-4);
  }

  .page-features .board__title {
    font-size: var(--text-2xl);
  }

  .page-features .board-table__title {
    font-size: var(--text-3xl);
  }

  .page-features .board-exit__title {
    font-size: var(--text-2xl);
  }

  .page-features .board-exit__links {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: var(--space-6);
  }
}

/* ---------- 桌面 ---------- */
@media (min-width: 900px) {
  .page-features .board-hero {
    padding-top: var(--space-6);
  }

  .page-features .board-hero__frame {
    padding: var(--space-8) var(--space-6);
  }

  .page-features .board-hero__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: var(--space-8);
    align-items: start;
  }

  .page-features .board-hero__side {
    padding-left: var(--space-6);
    min-height: 100%;
  }

  .page-features .board-hero__media img {
    height: 100%;
    min-height: 320px;
  }

  .page-features .fig__note {
    max-height: 0;
    margin-top: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height 240ms ease-out, opacity 240ms ease-out, margin-top 240ms ease-out;
  }

  .page-features .fig:hover .fig__note,
  .page-features .fig:focus .fig__note,
  .page-features .fig:focus-within .fig__note {
    max-height: calc(var(--space-8) * 2);
    margin-top: var(--space-2);
    opacity: 1;
  }

  .page-features .board__summary {
    grid-template-columns: auto minmax(0, 1fr) auto;
  }

  .page-features .board__title {
    font-size: var(--text-3xl);
  }

  .page-features .board__hint {
    display: block;
    align-self: baseline;
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    letter-spacing: 0.08em;
    color: var(--color-ink-muted);
  }

  .page-features .board__hint::after {
    content: "收起";
  }

  .page-features .board:not([open]) .board__hint::after {
    content: "展开";
  }

  .page-features .board--b {
    margin-left: calc(var(--space-6) * 1);
  }

  .page-features .board--c {
    margin-left: calc(var(--space-6) * 2);
  }

  .page-features .board--d {
    margin-left: calc(var(--space-6) * 3);
  }

  .page-features .board__split {
    display: grid;
    grid-template-columns: minmax(0, 1.7fr) minmax(0, 1fr);
    gap: var(--space-6);
    align-items: start;
  }

  .page-features .board__media--side {
    margin: var(--space-3) 0 0;
  }

  .page-features .board__media--square {
    max-width: 420px;
    margin: var(--space-6) 0 0;
  }

  .page-features .board-exit__links {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

/* ---------- 减少动效 ---------- */
@media (prefers-reduced-motion: reduce) {
  .page-features .board__summary::before,
  .page-features .fig__note,
  .page-features .board__out {
    transition: none;
  }

  .page-features .board__summary:hover::before,
  .page-features .board__summary:focus-visible::before {
    transform: none;
  }
}