.page-features {
  --fn-value-col: calc(var(--space-8) * 3);
  --fn-cell-pad: var(--space-3);
}

/* ---------- 首屏 ---------- */
.page-features .fn-hero {
  background: var(--color-surface);
}

.page-features .fn-hero__head {
  padding-block: var(--space-3) var(--space-8);
}

.page-features .fn-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);
  overflow-wrap: break-word;
}

.page-features .fn-hero__lede {
  margin: var(--space-6) 0 0;
  max-width: var(--measure);
  font-size: var(--text-lg);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

/* ---------- 首屏指标带 ---------- */
.page-features .fn-band {
  display: grid;
  grid-template-columns: 1fr;
}

.page-features .fn-band__cell {
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: var(--space-1);
  padding: var(--space-6) var(--fn-cell-pad);
  min-height: calc(var(--space-8) * 2.5);
}

.page-features .fn-band__cell--accent {
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

.page-features .fn-band__cell--primary {
  background: var(--color-primary);
  color: var(--color-primary-ink);
}

.page-features .fn-band__figure {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-3xl);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.03em;
  font-variant-numeric: tabular-nums;
}

.page-features .fn-band__label {
  margin: var(--space-3) 0 0;
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
}

.page-features .fn-band__caliber {
  margin: 0;
  font-size: var(--text-xs);
  line-height: var(--leading-body);
  color: color-mix(in srgb, currentColor 82%, transparent);
  max-width: 32ch;
}

/* ---------- 筛选与总标题 ---------- */
.page-features .fn-groups {
  padding-block: var(--space-8) 0;
  background: var(--color-surface);
}

.page-features .fn-groups__bar {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-3);
  padding-bottom: var(--space-4);
}

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

.page-features .filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.page-features .filter-chip {
  appearance: none;
  border: 0;
  border-radius: var(--radius-sm);
  background: var(--color-primary-soft);
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  line-height: 1;
  padding: var(--space-2) var(--space-3);
  min-height: 44px;
  cursor: pointer;
  transition: background-color 180ms ease, color 180ms ease;
}

.page-features .filter-chip:hover {
  background: var(--color-primary);
  color: var(--color-primary-ink);
}

.page-features .filter-chip[aria-pressed="true"],
.page-features .filter-chip.is-active {
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

.page-features .filter-chip:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

.page-features .filter-count {
  font-family: var(--font-mono);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.page-features .filter-empty {
  margin: var(--space-4) 0 0;
  padding: var(--space-3);
  background: var(--color-surface-deep);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

/* ---------- 分组编号尺 ---------- */
.page-features .fn-rule {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

.page-features .fn-rule__num {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-accent);
  letter-spacing: 0.06em;
}

.page-features .fn-rule__track {
  flex: 0 0 auto;
  width: calc(var(--space-8) * 2);
  max-width: 40%;
  height: var(--space-1);
  color: var(--color-ink-muted);
  background-image: repeating-linear-gradient(
    90deg,
    currentColor 0 1px,
    transparent 1px var(--space-1)
  );
  opacity: 0.7;
}

.page-features .fn-rule__label {
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  letter-spacing: 0.02em;
  color: var(--color-ink-soft);
}

/* ---------- 分组 ---------- */
.page-features .fn-group {
  padding-block: var(--space-8);
  background: var(--color-surface);
}

.page-features .fn-group--deep {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.page-features .fn-group--deep .fn-rule__num {
  color: var(--color-contrast-accent);
}

.page-features .fn-group--deep .fn-rule__track {
  color: var(--color-contrast-line);
}

.page-features .fn-group--deep .fn-rule__label {
  color: color-mix(in srgb, var(--color-contrast-ink) 70%, transparent);
}

.page-features .fn-group__head {
  margin-bottom: var(--space-6);
}

.page-features .fn-group__head h3 {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  color: inherit;
}

.page-features .fn-group__note {
  margin: var(--space-2) 0 0;
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-features .fn-group--deep .fn-group__note {
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
}

.page-features .fn-group__split {
  display: grid;
  gap: var(--space-6);
}

/* ---------- 指标列表 ---------- */
.page-features .fn-metrics {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-features .fn-metric {
  position: relative;
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-2);
  padding: var(--space-4) var(--space-1);
  margin-inline: calc(var(--space-1) * -1);
  transition: background-color 180ms ease;
}

.page-features .fn-metric + .fn-metric {
  border-top: var(--border-thin) solid var(--color-line);
}

.page-features .fn-group--deep .fn-metric + .fn-metric {
  border-top-color: var(--color-contrast-line);
}

.page-features .fn-metric:hover {
  background: var(--color-highlight);
}

.page-features .fn-group--deep .fn-metric:hover {
  background: color-mix(in srgb, var(--color-contrast-accent) 16%, transparent);
}

.page-features .fn-metric--flagged::before {
  content: "";
  position: absolute;
  inset-inline-start: calc(var(--space-1) * -1 - var(--space-1));
  inset-block: var(--space-4);
  width: var(--space-1);
  background: var(--color-accent);
}

.page-features .fn-metric__value {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
  color: var(--color-ink);
}

.page-features .fn-metric__value--accent {
  color: var(--color-accent);
}

.page-features .fn-group--deep .fn-metric__value {
  color: var(--color-contrast-ink);
}

.page-features .fn-group--deep .fn-metric__value--accent {
  color: var(--color-contrast-accent);
}

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

.page-features .fn-metric__caliber {
  margin: var(--space-2) 0 0;
  max-width: var(--measure);
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-features .fn-group--deep .fn-metric__caliber,
.page-features .fn-group--deep .fn-metric__detail p {
  color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent);
}

.page-features .fn-metric__detail {
  margin-top: var(--space-2);
}

.page-features .fn-metric__detail summary {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  min-height: 36px;
  list-style: none;
  cursor: pointer;
  font-family: var(--font-heading);
  font-size: var(--text-xs);
  font-weight: var(--weight-heading);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.page-features .fn-metric__detail summary::-webkit-details-marker {
  display: none;
}

.page-features .fn-metric__detail summary::before {
  content: "";
  width: var(--space-2);
  height: var(--space-2);
  background: currentColor;
  clip-path: polygon(0 0, 100% 50%, 0 100%);
  transition: transform 180ms ease;
}

.page-features .fn-metric__detail[open] summary::before {
  transform: rotate(90deg);
}

.page-features .fn-metric__detail summary:hover,
.page-features .fn-metric__detail summary:focus-visible {
  color: var(--color-accent);
}

.page-features .fn-metric__detail summary:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

.page-features .fn-group--deep .fn-metric__detail summary {
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.page-features .fn-metric__detail p {
  margin: var(--space-1) 0 0;
  max-width: var(--measure);
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

/* ---------- 图形 ---------- */
.page-features .fn-figure {
  margin: 0;
}

.page-features .fn-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--radius-sm);
  background: var(--color-surface-deep);
}

.page-features .fn-group--deep .fn-figure img {
  background: var(--color-contrast-line);
}

.page-features .fn-figure figcaption {
  margin-top: var(--space-2);
  max-width: 44ch;
  font-size: var(--text-xs);
  line-height: var(--leading-body);
  color: var(--color-ink-muted);
}

.page-features .fn-group--deep .fn-figure figcaption {
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

/* ---------- 字段区块 ---------- */
.page-features .fn-fields {
  padding-block: var(--space-8);
  background: var(--color-surface-alt);
}

.page-features .fn-fields__title {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  color: var(--color-ink);
}

.page-features .fn-fields__lede {
  margin: var(--space-3) 0 0;
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-features .fn-fields__grid {
  list-style: none;
  margin: var(--space-6) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-3);
  counter-reset: fn-field;
}

.page-features .fn-field {
  background: var(--color-surface);
  border-radius: var(--radius-sm);
  padding: var(--space-4);
}

.page-features .fn-field__count {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--color-accent);
  font-variant-numeric: tabular-nums;
}

.page-features .fn-field__name {
  margin: var(--space-2) 0 0;
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  color: var(--color-ink);
}

.page-features .fn-field__items {
  margin: var(--space-2) 0 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: var(--leading-body);
  letter-spacing: 0.01em;
  color: var(--color-ink-soft);
}

.page-features .fn-field__note {
  margin: var(--space-2) 0 0;
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-ink-muted);
}

.page-features .fn-fields__link {
  margin: var(--space-6) 0 0;
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-features .fn-fields__link a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 2px;
}

.page-features .fn-fields__link a:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

/* ---------- 订阅 ---------- */
.page-features .fn-subscribe {
  padding-block: var(--space-8);
  background: var(--color-primary);
  color: var(--color-primary-ink);
}

.page-features .fn-subscribe__title {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
}

.page-features .fn-subscribe__lede {
  margin: var(--space-3) 0 0;
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: color-mix(in srgb, var(--color-primary-ink) 88%, transparent);
}

.page-features .fn-flow {
  list-style: none;
  margin: var(--space-4) 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.page-features .fn-flow__step {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius-sm);
  background: color-mix(in srgb, var(--color-primary-ink) 16%, transparent);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  line-height: 1.4;
}

.page-features .fn-flow__step .num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-primary-ink) 72%, transparent);
}

.page-features .fn-subscribe__note {
  margin: var(--space-4) 0 0;
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: color-mix(in srgb, var(--color-primary-ink) 88%, transparent);
}

.page-features .fn-subscribe__note a {
  color: var(--color-primary-ink);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 2px;
}

.page-features .fn-subscribe__note a:focus-visible {
  outline: 2px solid var(--color-primary-ink);
  outline-offset: 2px;
}

/* ---------- 继续查阅 ---------- */
.page-features .fn-tail {
  padding-block: var(--space-8);
  background: var(--color-surface);
}

.page-features .fn-tail__title {
  margin: 0 0 var(--space-4);
  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 .fn-tail__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-1);
}

.page-features .fn-tail__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-areas:
    "id name"
    "id desc";
  column-gap: var(--space-3);
  row-gap: var(--space-1);
  padding: var(--space-3) var(--space-2);
  border-radius: var(--radius-sm);
  background: var(--color-surface-alt);
  text-decoration: none;
  transition: background-color 180ms ease, color 180ms ease;
}

.page-features .fn-tail__item:hover {
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

.page-features .fn-tail__item:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

.page-features .fn-tail__id {
  grid-area: id;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
  padding-top: 0.35em;
}

.page-features .fn-tail__item:hover .fn-tail__id {
  color: color-mix(in srgb, var(--color-accent-ink) 78%, transparent);
}

.page-features .fn-tail__name {
  grid-area: name;
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  color: var(--color-ink);
}

.page-features .fn-tail__item:hover .fn-tail__name,
.page-features .fn-tail__item:hover .fn-tail__desc {
  color: var(--color-accent-ink);
}

.page-features .fn-tail__desc {
  grid-area: desc;
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-features .fn-tail__note {
  margin: var(--space-4) 0 0;
  max-width: var(--measure);
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-ink-muted);
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-features .fn-band {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

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

@media (min-width: 900px) {
  .page-features .fn-group__split {
    grid-template-columns: minmax(0, 1.55fr) minmax(0, 1fr);
    gap: var(--space-8);
    align-items: start;
  }

  .page-features .fn-group__split--reverse {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.55fr);
  }

  .page-features .fn-group__split--reverse .fn-figure {
    order: -1;
  }

  .page-features .fn-metric {
    grid-template-columns: var(--fn-value-col) minmax(0, 1fr);
    gap: var(--space-6);
    align-items: start;
  }

  .page-features .fn-metrics {
    min-width: 0;
  }

  .page-features .fn-fields__grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 1000px) {
  .page-features .fn-band {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-features .fn-band__cell {
    min-height: calc(var(--space-8) * 3.2);
  }

  .page-features .fn-groups__bar {
    align-items: center;
  }
}

@media (min-width: 1200px) {
  .page-features .fn-value-col-fallback {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-features .fn-metric,
  .page-features .filter-chip,
  .page-features .fn-tail__item,
  .page-features .fn-metric__detail summary::before {
    transition: none;
  }
}