.page-standards {
  --st-pad-y: var(--section-y);
  --st-node-num: var(--text-xl);
  --st-num-col: 3.5rem;
  --st-ink: var(--color-ink);
  --st-ink-soft: var(--color-ink-soft);
  --st-num: var(--color-primary);
  --st-accent: var(--color-accent);
  --st-rule: var(--color-line);
  display: block;
  background: var(--color-surface);
  color: var(--color-ink);
  overflow-x: hidden;
}

.page-standards .st-band--primary {
  --st-ink: var(--color-primary-ink);
  --st-ink-soft: color-mix(in srgb, var(--color-primary-ink) 78%, transparent);
  --st-num: var(--color-primary-ink);
  --st-accent: var(--color-primary-ink);
  --st-rule: color-mix(in srgb, var(--color-primary-ink) 30%, transparent);
}

.page-standards .st-band--deep {
  --st-ink: var(--color-contrast-ink);
  --st-ink-soft: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent);
  --st-num: var(--color-contrast-accent);
  --st-accent: var(--color-contrast-accent);
  --st-rule: var(--color-contrast-line);
}

/* ============ 首屏 ============ */
.page-standards .st-hero {
  background: var(--color-primary);
  color: var(--color-primary-ink);
}

.page-standards .st-hero__head {
  padding-top: var(--space-6);
  padding-bottom: var(--space-6);
}

.page-standards .st-crumb {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-primary-ink);
  margin: 0 0 var(--space-3);
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.page-standards .st-crumb a {
  color: var(--color-primary-ink);
  text-decoration: none;
  border-bottom: var(--border-thin) solid color-mix(in srgb, var(--color-primary-ink) 45%, transparent);
}

.page-standards .st-crumb a:hover {
  border-bottom-color: var(--color-primary-ink);
}

.page-standards .st-hero__title {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: 900;
  line-height: 0.98;
  letter-spacing: var(--tracking-heading);
  margin: 0 0 var(--space-3);
  transform: scaleX(1.02);
  transform-origin: left center;
}

.page-standards .st-hero__lede {
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  max-width: var(--measure);
  margin: 0;
  color: color-mix(in srgb, var(--color-primary-ink) 88%, transparent);
}

/* 轨道 */
.page-standards .st-track {
  position: relative;
  isolation: isolate;
}

.page-standards .st-track__media {
  position: absolute;
  inset: 0;
  z-index: -1;
  overflow: hidden;
}

.page-standards .st-track__media img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.page-standards .st-track__scrim {
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
}

.page-standards .st-track__row {
  display: flex;
  align-items: flex-end;
  gap: var(--space-1);
  padding-top: var(--space-8);
  padding-bottom: var(--space-6);
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-standards .st-track__start {
  display: none;
  flex: 0 0 auto;
  writing-mode: vertical-rl;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.32em;
  color: color-mix(in srgb, var(--color-primary-ink) 72%, transparent);
  align-self: stretch;
  padding-right: var(--space-1);
}

.page-standards .st-node {
  flex: 1 1 0;
  min-width: 76px;
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-1);
  color: var(--color-primary-ink);
  text-decoration: none;
  transition: background-color 120ms ease-out, color 120ms ease-out;
}

.page-standards .st-node__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--st-node-num);
  font-weight: 900;
  line-height: 0.86;
  letter-spacing: -0.02em;
}

.page-standards .st-node__name {
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 700;
  white-space: nowrap;
}

.page-standards .st-node--now {
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

.page-standards .st-node:hover,
.page-standards .st-node:focus-visible {
  background: var(--color-primary-ink);
  color: var(--color-primary);
  outline: none;
}

.page-standards .st-node:focus-visible {
  box-shadow: 0 0 0 var(--border-thick) var(--color-focus);
}

.page-standards .st-track__total {
  flex: 0 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  align-items: flex-end;
  padding-left: var(--space-2);
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  text-align: right;
}

.page-standards .st-track__total-k {
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  color: color-mix(in srgb, var(--color-primary-ink) 66%, transparent);
}

.page-standards .st-track__total-v {
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--color-primary-ink);
  white-space: nowrap;
}

/* ============ 章节 ============ */
.page-standards .st-band {
  padding: var(--st-pad-y) 0;
}

.page-standards .st-band--light {
  background: var(--color-surface);
  color: var(--st-ink);
}

.page-standards .st-band--primary {
  background: var(--color-primary);
  color: var(--st-ink);
}

.page-standards .st-band--deep {
  background: var(--color-contrast-surface);
  color: var(--st-ink);
}

.page-standards .st-head {
  display: grid;
  gap: var(--space-2);
  margin-bottom: var(--space-6);
  max-width: var(--measure);
}

.page-standards .st-head__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-base);
  font-weight: 700;
  letter-spacing: 0.14em;
  color: var(--st-accent);
}

.page-standards .st-head__title {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: 800;
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  margin: 0;
  color: var(--st-ink);
}

.page-standards .st-head__sub {
  font-size: var(--text-base);
  line-height: var(--leading-body);
  margin: 0;
  color: var(--st-ink-soft);
}

/* ============ 分栏 ============ */
.page-standards .st-split {
  display: grid;
  gap: var(--space-6);
}

.page-standards .st-steps {
  display: grid;
  gap: var(--space-6);
}

.page-standards .st-steps--wide {
  max-width: var(--container);
}

/* ============ 单环节 ============ */
.page-standards .st-step {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-2);
}

.page-standards .st-step__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-2xl);
  font-weight: 900;
  line-height: 0.82;
  letter-spacing: -0.02em;
  color: var(--st-num);
}

.page-standards .st-step__body {
  display: grid;
  gap: var(--space-2);
}

.page-standards .st-step__title {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 800;
  line-height: 1.2;
  margin: 0;
  color: var(--st-ink);
}

.page-standards .st-step__text {
  font-size: var(--text-base);
  line-height: var(--leading-body);
  margin: 0;
  color: var(--st-ink-soft);
  max-width: var(--measure);
}

.page-standards .st-step__facts {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-1);
}

.page-standards .st-step__facts li {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-2);
  background: color-mix(in srgb, var(--st-ink) 5%, transparent);
  transition: background-color 120ms ease-out;
}

.page-standards .st-step__facts li:hover {
  background: color-mix(in srgb, var(--st-ink) 12%, transparent);
}

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

.page-standards .st-step__v {
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--st-ink);
}

.page-standards .st-step__out {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
  margin: 0;
}

.page-standards .st-out-link {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--st-ink);
  text-decoration: none;
  padding: var(--space-1) var(--space-2);
  background: color-mix(in srgb, var(--st-ink) 8%, transparent);
  transition: background-color 120ms ease-out, color 120ms ease-out;
}

.page-standards .st-out-link:hover,
.page-standards .st-out-link:focus-visible {
  background: var(--st-accent);
  color: var(--color-accent-ink);
  outline: none;
}

/* ============ 图 ============ */
.page-standards .st-figure {
  position: relative;
  margin: 0;
}

.page-standards .st-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-standards .st-figure__tag {
  position: absolute;
  left: 0;
  bottom: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  padding: var(--space-1) var(--space-2);
  background: var(--color-surface-deep);
  color: var(--color-ink-muted);
}

.page-standards .st-figure--wide {
  margin-bottom: var(--space-6);
}

/* ============ 对照表 ============ */
.page-standards .st-table-wrap {
  overflow-x: auto;
}

.page-standards .st-table {
  width: 100%;
  min-width: 620px;
  border-collapse: collapse;
  font-size: var(--text-sm);
}

.page-standards .st-table__cap {
  text-align: left;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
  padding-bottom: var(--space-2);
}

.page-standards .st-table th {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: 0.06em;
  text-align: left;
  color: var(--color-ink);
  padding: var(--space-2);
  border-bottom: var(--border-thick) solid var(--color-ink);
}

.page-standards .st-table td {
  padding: var(--space-3) var(--space-2);
  color: var(--color-ink);
  line-height: 1.5;
  vertical-align: top;
  border-bottom: var(--border-thin) solid var(--st-rule);
}

.page-standards .st-table tbody tr {
  transition: background-color 120ms ease-out;
}

.page-standards .st-table tbody tr:hover {
  background: var(--color-highlight);
}

.page-standards .st-table__idx {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-weight: 900;
  font-size: var(--text-lg);
  line-height: 1;
  color: var(--color-primary);
  text-align: right;
  white-space: nowrap;
}

.page-standards .st-table__time {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  color: var(--color-ink);
  white-space: nowrap;
}

/* ============ 下一步 ============ */
.page-standards .st-next {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-6);
}

.page-standards .st-next__item {
  display: grid;
  gap: var(--space-2);
  padding-top: var(--space-4);
  border-top: var(--border-thin) solid var(--st-rule);
}

.page-standards .st-next__title {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 800;
  margin: 0;
  color: var(--color-primary-ink);
}

.page-standards .st-next__text {
  font-size: var(--text-base);
  line-height: var(--leading-body);
  margin: 0;
  max-width: var(--measure);
  color: color-mix(in srgb, var(--color-primary-ink) 86%, transparent);
}

.page-standards .st-next__link {
  justify-self: start;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  text-decoration: none;
  color: var(--color-primary-ink);
  padding: var(--space-2) var(--space-3);
  background: color-mix(in srgb, var(--color-primary-ink) 14%, transparent);
  transition: background-color 120ms ease-out, color 120ms ease-out;
}

.page-standards .st-next__link:hover,
.page-standards .st-next__link:focus-visible {
  background: var(--color-primary-ink);
  color: var(--color-primary);
  outline: none;
}

.page-standards .st-next__link:focus-visible {
  box-shadow: 0 0 0 var(--border-thick) var(--color-focus);
}

/* ============ 响应式 ============ */
@media (min-width: 640px) {
  .page-standards {
    --st-num-col: 4.5rem;
    --st-node-num: var(--text-2xl);
  }

  .page-standards .st-step {
    grid-template-columns: var(--st-num-col) minmax(0, 1fr);
    gap: var(--space-4);
  }

  .page-standards .st-step__facts li {
    grid-template-columns: 6.5rem minmax(0, 1fr);
    gap: var(--space-3);
    align-items: baseline;
  }

  .page-standards .st-head__title {
    font-size: var(--text-2xl);
  }

  .page-standards .st-next {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: var(--space-4);
  }
}

@media (min-width: 900px) {
  .page-standards {
    --st-pad-y: var(--section-y-lg);
    --st-node-num: var(--text-3xl);
  }

  .page-standards .st-split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 3fr);
    gap: var(--space-8);
    align-items: start;
  }

  .page-standards .st-split--reverse {
    grid-template-columns: minmax(0, 3fr) minmax(0, 7fr);
  }

  .page-standards .st-split--reverse .st-figure {
    order: -1;
  }

  .page-standards .st-track__start {
    display: flex;
  }

  .page-standards .st-node {
    min-width: 0;
    padding: var(--space-3) var(--space-2);
  }

  .page-standards .st-node__name {
    white-space: normal;
  }
}

@media (min-width: 1200px) {
  .page-standards .st-node__num {
    letter-spacing: -0.03em;
  }
}