.page-start .start-hero {
  padding-top: calc(var(--section-y-lg) + var(--space-4));
  padding-bottom: var(--section-y-lg);
}

.page-start .start-hero__crumbs {
  margin-bottom: var(--space-6);
  color: color-mix(in srgb, var(--color-primary-ink) 70%, transparent);
}

.page-start .start-hero__crumbs a {
  color: inherit;
  text-decoration: none;
}

.page-start .start-hero__crumbs a:hover {
  text-decoration: underline;
}

.page-start .start-hero__grid {
  display: grid;
  gap: var(--space-6);
}

.page-start .start-hero__kicker {
  color: color-mix(in srgb, var(--color-primary-ink) 78%, transparent);
  letter-spacing: 0.22em;
}

.page-start .start-hero__title {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  line-height: 0.92;
  letter-spacing: var(--tracking-heading);
  font-weight: var(--weight-heading);
  color: var(--color-primary-ink);
  margin: var(--space-3) 0 0;
  max-width: 15ch;
}

.page-start .start-hero__lede {
  margin: var(--space-6) 0 0;
  max-width: var(--measure);
  color: color-mix(in srgb, var(--color-primary-ink) 86%, transparent);
}

.page-start .start-figures {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4) var(--space-6);
  margin: var(--space-8) 0 0;
  padding: 0;
  list-style: none;
}

.page-start .start-figures li {
  display: grid;
  gap: 2px;
}

.page-start .start-figures__num {
  font-family: var(--font-mono);
  font-size: var(--text-xl);
  line-height: 1;
  font-variant-numeric: tabular-nums;
  color: var(--color-primary-ink);
}

.page-start .start-figures__label {
  font-size: var(--text-sm);
  letter-spacing: 0.16em;
  color: color-mix(in srgb, var(--color-primary-ink) 68%, transparent);
}

.page-start .start-hero__aside {
  padding-top: var(--space-4);
}

.page-start .start-hero__aside-label {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.2em;
  color: color-mix(in srgb, var(--color-primary-ink) 66%, transparent);
  margin: 0;
}

.page-start .start-hero__groups {
  list-style: none;
  margin: var(--space-3) 0 0;
  padding: 0;
  display: grid;
  gap: var(--space-3);
}

.page-start .start-hero__groups li {
  display: grid;
  gap: 2px;
}

.page-start .start-hero__groups a {
  color: var(--color-primary-ink);
  text-decoration: none;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  letter-spacing: 0.02em;
  line-height: 1.3;
}

.page-start .start-hero__groups a:hover,
.page-start .start-hero__groups a:focus-visible {
  text-decoration: underline;
}

.page-start .start-hero__range {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-primary-ink) 62%, transparent);
}

.page-start .start-hero__figure {
  margin: var(--space-8) 0 0;
}

.page-start .start-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
}

/* ---------- 文档区 ---------- */

.page-start .start-doc {
  padding-top: var(--section-y-lg);
  padding-bottom: var(--section-y-lg);
}

.page-start .start-doc__grid {
  display: grid;
  gap: var(--space-6);
}

.page-start .start-toc {
  display: grid;
  gap: var(--space-2);
  padding-bottom: var(--space-2);
}

.page-start .start-toc__label {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.2em;
  color: var(--color-ink-muted);
  margin: 0;
}

.page-start .start-toc__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-start .start-toc__group {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
  margin-top: var(--space-3);
  padding-bottom: var(--space-1);
}

.page-start .start-toc__list > .start-toc__group:first-child {
  margin-top: 0;
}

.page-start .start-toc__list a {
  display: grid;
  grid-template-columns: 2.2rem minmax(0, 1fr);
  gap: var(--space-1);
  align-items: baseline;
  padding: 5px 0 5px var(--space-2);
  font-size: var(--text-sm);
  line-height: 1.45;
  color: var(--color-ink-soft);
  text-decoration: none;
  position: relative;
}

.page-start .start-toc__list a::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.85em;
  width: 6px;
  height: 6px;
  background: var(--color-line);
}

.page-start .start-toc__list a:hover,
.page-start .start-toc__list a:focus-visible {
  color: var(--color-ink);
}

.page-start .start-toc__list a:hover::before,
.page-start .start-toc__list a:focus-visible::before {
  background: var(--color-accent);
}

.page-start .start-toc__list a[aria-current="true"],
.page-start .start-toc__list a.is-current {
  color: var(--color-primary);
  font-weight: var(--weight-heading);
}

.page-start .start-toc__list a[aria-current="true"]::before,
.page-start .start-toc__list a.is-current::before {
  background: var(--color-primary);
  height: 14px;
  top: 0.5em;
}

.page-start .start-toc__no {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.page-start .start-body {
  width: 100%;
  max-width: var(--measure);
}

.page-start .start-group {
  padding-top: var(--section-y);
}

.page-start .start-body > .start-group:first-child {
  padding-top: 0;
}

.page-start .start-group__head {
  display: grid;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

.page-start .start-group__kicker {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.24em;
  color: var(--color-accent);
  margin: 0;
}

.page-start .start-group__title {
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  line-height: 1.06;
  letter-spacing: var(--tracking-heading);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
  margin: 0;
  scroll-margin-top: var(--space-8);
}

.page-start .start-group__head::after {
  content: "";
  width: 72px;
  height: 6px;
  background: var(--color-primary);
  margin-top: var(--space-2);
}

.page-start .start-group__lead {
  margin: var(--space-2) 0 0;
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-start .start-sec {
  padding-top: var(--space-6);
  scroll-margin-top: var(--space-8);
}

.page-start .start-sec__title {
  display: grid;
  grid-template-columns: 2.4rem minmax(0, 1fr);
  gap: var(--space-2);
  align-items: baseline;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1.25;
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
  margin: 0 0 var(--space-3);
}

.page-start .start-sec__no {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  color: var(--color-accent);
}

.page-start .start-sec p {
  margin: 0 0 var(--space-3);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink);
}

.page-start .start-sec p.start-point {
  display: grid;
  grid-template-columns: 8px minmax(0, 1fr);
  gap: var(--space-2);
  margin: var(--space-4) 0 0;
  font-size: var(--text-sm);
  line-height: 1.65;
  color: var(--color-ink-soft);
}

.page-start .start-sec p.start-point::before {
  content: "";
  width: 8px;
  height: 8px;
  margin-top: 0.55em;
  background: var(--color-accent);
}

.page-start .start-figure {
  margin: var(--space-4) 0 var(--space-4);
}

.page-start .start-figure img {
  display: block;
  width: 100%;
  height: auto;
}

.page-start .start-table-wrap {
  margin: var(--space-4) 0;
  overflow-x: auto;
}

.page-start .start-fields {
  width: 100%;
  min-width: 34rem;
  border-collapse: collapse;
  font-size: var(--text-sm);
}

.page-start .start-fields__caption {
  text-align: left;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
  padding-bottom: var(--space-2);
}

.page-start .start-fields th,
.page-start .start-fields td {
  text-align: left;
  vertical-align: top;
  padding: var(--space-2) var(--space-3) var(--space-2) 0;
  border-bottom: var(--border-thin) solid var(--color-line);
  line-height: 1.6;
}

.page-start .start-fields th {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
  letter-spacing: 0.06em;
}

.page-start .start-fields td {
  color: var(--color-ink-soft);
}

.page-start .start-fields td:first-child {
  font-family: var(--font-mono);
  color: var(--color-ink);
  white-space: nowrap;
}

.page-start .start-states {
  list-style: none;
  margin: var(--space-3) 0;
  padding: 0;
  display: grid;
  gap: var(--space-3);
}

.page-start .start-states li {
  display: grid;
  grid-template-columns: 4.5rem minmax(0, 1fr);
  gap: var(--space-3);
  align-items: start;
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-start .start-states__tag {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-accent-ink);
  background: var(--color-accent);
  padding: 2px 6px;
  text-align: center;
}

.page-start .start-key {
  margin-top: var(--space-6);
  background: var(--color-primary-soft);
  padding: var(--space-4);
}

.page-start .start-key summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  cursor: pointer;
  list-style: none;
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  letter-spacing: 0.06em;
  color: var(--color-ink);
}

.page-start .start-key summary::-webkit-details-marker {
  display: none;
}

.page-start .start-key summary::after {
  content: "＋";
  font-family: var(--font-mono);
  color: var(--color-primary);
}

.page-start .start-key[open] summary::after {
  content: "－";
}

.page-start .start-key:focus-visible,
.page-start .start-key summary:focus-visible {
  outline: var(--border-thick) solid var(--color-focus);
  outline-offset: 2px;
}

.page-start .start-key__body {
  list-style: none;
  margin: var(--space-3) 0 0;
  padding: 0;
  display: grid;
  gap: var(--space-2);
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-ink-soft);
}

.page-start .start-key__body li {
  padding-left: var(--space-3);
  position: relative;
}

.page-start .start-key__body li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 6px;
  height: 6px;
  background: var(--color-primary);
}

/* ---------- 收尾区 ---------- */

.page-start .start-outro {
  padding-top: var(--section-y-lg);
  padding-bottom: var(--section-y-lg);
}

.page-start .start-outro__grid {
  display: grid;
  gap: var(--space-6);
}

.page-start .start-outro__kicker {
  color: color-mix(in srgb, var(--color-accent-ink) 76%, transparent);
  letter-spacing: 0.22em;
}

.page-start .start-outro__title {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  line-height: 1.1;
  letter-spacing: var(--tracking-heading);
  font-weight: var(--weight-heading);
  color: var(--color-accent-ink);
  margin: var(--space-2) 0 0;
}

.page-start .start-outro__text {
  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-accent-ink) 84%, transparent);
}

.page-start .start-next {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-4);
}

.page-start .start-next li {
  display: grid;
  gap: 4px;
}

.page-start .start-next a {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: 0.02em;
  color: var(--color-accent-ink);
  text-decoration: none;
}

.page-start .start-next a:hover,
.page-start .start-next a:focus-visible {
  text-decoration: underline;
}

.page-start .start-next span {
  font-size: var(--text-sm);
  line-height: 1.65;
  color: color-mix(in srgb, var(--color-accent-ink) 78%, transparent);
}

.page-start .start-outro__note {
  margin: var(--space-8) 0 0;
  max-width: var(--measure);
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-accent-ink) 82%, transparent);
}

/* ---------- 响应式 ---------- */

@media (min-width: 560px) {
  .page-start .start-toc__list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: var(--space-4);
  }

  .page-start .start-toc__group {
    grid-column: 1 / -1;
  }
}

@media (min-width: 760px) {
  .page-start .start-outro__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: var(--space-8);
    align-items: start;
  }

  .page-start .start-states li {
    grid-template-columns: 5rem minmax(0, 1fr);
  }
}

@media (min-width: 900px) {
  .page-start .start-hero__grid {
    grid-template-columns: minmax(0, 1fr) 15rem;
    gap: var(--space-8);
    align-items: start;
  }

  .page-start .start-hero__aside {
    padding: var(--space-4) 0 var(--space-4) var(--space-4);
    background: color-mix(in srgb, var(--color-primary-ink) 9%, transparent);
  }
}

@media (min-width: 1000px) {
  .page-start .start-doc__grid {
    grid-template-columns: 14.5rem minmax(0, 1fr);
    gap: var(--space-8);
    align-items: start;
  }

  .page-start .start-toc {
    position: sticky;
    top: var(--space-8);
    max-height: calc(100vh - (var(--space-8) * 2));
    overflow-y: auto;
  }

  .page-start .start-toc__list {
    grid-template-columns: minmax(0, 1fr);
  }
}