.page-start {
  display: block;
}

/* ---------- 首屏 ---------- */

.page-start .start-hero {
  position: relative;
  padding: var(--space-8) 0 var(--space-6);
  border-bottom: var(--border-thin) solid var(--color-line);
  background:
    radial-gradient(120% 80% at 85% 0%, color-mix(in srgb, var(--color-primary) 22%, transparent) 0%, transparent 62%),
    linear-gradient(180deg, var(--color-surface-alt) 0%, var(--color-surface) 78%);
}

.page-start .pg-crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  margin-bottom: var(--space-4);
  font-size: var(--text-sm);
  font-family: var(--font-mono);
  color: var(--color-ink-muted);
}

.page-start .pg-crumbs a {
  color: var(--color-ink-soft);
  text-decoration: none;
}

.page-start .pg-crumbs a:hover {
  color: var(--color-accent);
}

.page-start .start-hero__kicker {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin: 0 0 var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.02em;
  color: var(--color-ink-soft);
}

.page-start .start-hero__title {
  margin: 0 0 var(--space-4);
  max-width: 14ch;
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 0.98;
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.page-start .start-hero__title .pg-em {
  display: inline-block;
  font-style: normal;
  color: var(--color-accent);
}

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

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

.page-start .start-hero__track {
  min-width: 0;
}

/* 步骤节点骨架：窄屏为横向进度点 */

.page-start .start-track {
  display: flex;
  flex-wrap: nowrap;
  gap: var(--space-1);
  margin: 0 0 var(--space-4);
  padding: 0 0 var(--space-1);
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

.page-start .start-track::-webkit-scrollbar {
  display: none;
}

.page-start .start-track__item {
  position: relative;
  flex: 0 0 auto;
}

.page-start .start-track__link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-2);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-surface-alt);
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
  text-decoration: none;
  white-space: nowrap;
  transition: color 180ms ease, border-color 180ms ease, background-color 180ms ease;
}

.page-start .start-track__num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 700;
  color: var(--color-primary);
}

.page-start .start-track__link:hover {
  border-color: color-mix(in srgb, var(--color-accent) 55%, transparent);
  color: var(--color-ink);
}

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

.page-start .start-hero__figure {
  margin: 0;
  overflow: hidden;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  box-shadow: 0 0 28px color-mix(in srgb, var(--color-primary) 26%, transparent);
}

.page-start .start-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 4 / 3;
  object-fit: cover;
}

/* 右侧成组数字 */

.page-start .start-hero__stats {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-3);
  padding-top: var(--space-4);
  border-top: var(--border-thin) solid var(--color-line);
}

.page-start .start-stat {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  min-width: 0;
}

.page-start .start-stat__num {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: 700;
  line-height: 0.9;
  letter-spacing: -0.05em;
  color: var(--color-accent);
}

.page-start .start-stat__label {
  max-width: 20ch;
  font-size: var(--text-sm);
  line-height: 1.55;
  color: var(--color-ink-soft);
}

/* ---------- 分组头部 ---------- */

.page-start .start-group {
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-start .start-group__head {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  margin-bottom: var(--space-6);
}

.page-start .start-group__index {
  flex: 0 0 auto;
  padding-left: var(--space-2);
  border-left: var(--border-thick) solid var(--color-primary);
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: 700;
  line-height: 0.9;
  color: var(--color-primary);
}

.page-start .start-group__text {
  min-width: 0;
}

.page-start .start-group__title {
  margin: 0 0 var(--space-1);
  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-start .start-group__meta {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

/* ---------- 步骤列表 ---------- */

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

.page-start .start-step {
  position: relative;
  display: grid;
  grid-template-columns: var(--space-4) minmax(0, 1fr);
  gap: var(--space-2);
  align-items: start;
  scroll-margin-top: var(--space-8);
}

.page-start .start-step::after {
  content: "";
  position: absolute;
  left: calc(var(--space-2) - 0.5px);
  top: calc(var(--space-4) + var(--space-1));
  bottom: calc(-1 * var(--space-3) - var(--space-1));
  width: 1px;
  background: linear-gradient(180deg, color-mix(in srgb, var(--color-primary) 80%, transparent) 0%, transparent 92%);
  pointer-events: none;
}

.page-start .start-step:last-child::after {
  display: none;
}

.page-start .start-step__num {
  padding-top: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 700;
  line-height: 1;
  color: var(--color-ink-muted);
  transition: color 200ms ease;
}

.page-start .start-step:has(.start-step__fold[open]) .start-step__num {
  color: var(--color-accent);
}

.page-start .start-step__fold {
  min-width: 0;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface-alt);
  overflow: hidden;
  transition: border-color 200ms ease, box-shadow 200ms ease;
}

.page-start .start-step__fold[open] {
  border-color: color-mix(in srgb, var(--color-primary) 65%, transparent);
  box-shadow: 0 0 24px color-mix(in srgb, var(--color-primary) 22%, transparent);
}

.page-start .start-step__summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding: var(--space-3);
  cursor: pointer;
  list-style: none;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 600;
  line-height: 1.32;
  color: var(--color-ink);
}

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

.page-start .start-step__summary::after {
  content: "+";
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--color-ink-muted);
  transition: color 180ms ease;
}

.page-start .start-step__fold[open] .start-step__summary::after {
  content: "–";
  color: var(--color-accent);
}

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

.page-start .start-step__body {
  display: grid;
  gap: var(--space-3);
  padding: 0 var(--space-3) var(--space-3);
}

.page-start .start-step__body > p {
  max-width: var(--measure);
  margin: 0;
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-start .start-note {
  padding: var(--space-2) var(--space-3);
  border-left: var(--border-thick) solid var(--color-primary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: var(--color-primary-soft);
  font-size: var(--text-sm);
  line-height: 1.65;
  color: var(--color-ink);
}

.page-start .start-check {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-1) var(--space-2);
  padding-top: var(--space-2);
  border-top: var(--border-thin) dashed var(--color-line);
  font-size: var(--text-sm);
  line-height: 1.65;
  color: var(--color-ink);
}

.page-start .start-check__label {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-accent);
  border-bottom: var(--border-thin) solid var(--color-accent);
}

.page-start .start-check::before {
  content: "✓";
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--color-accent);
}

/* ---------- 章节配图 ---------- */

.page-start .start-wide-figure,
.page-start .start-narrow-figure {
  margin: 0 0 var(--space-6);
}

.page-start .start-wide-figure {
  overflow: hidden;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
}

.page-start .start-wide-figure .pg-figure__media {
  display: block;
}

.page-start .start-wide-figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 8 / 3;
  object-fit: cover;
}

.page-start .start-wide-figure .pg-figure__cap {
  padding: var(--space-2) var(--space-3);
  border-top: var(--border-thin) solid var(--color-line);
  background: var(--color-surface-alt);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

.page-start .start-narrow-figure {
  max-width: 34rem;
  margin-bottom: var(--space-6);
  margin-left: auto;
  overflow: hidden;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  box-shadow: 0 0 24px color-mix(in srgb, var(--color-primary) 20%, transparent);
}

.page-start .start-narrow-figure .pg-figure__media {
  display: block;
}

.page-start .start-narrow-figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

.page-start .start-narrow-figure .pg-figure__cap {
  padding: var(--space-2) var(--space-3);
  border-top: var(--border-thin) solid var(--color-line);
  background: var(--color-surface-alt);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

/* ---------- 浅底排查表 ---------- */

.page-start .start-trouble {
  border-top: var(--border-thin) solid var(--color-contrast-line);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.page-start .start-trouble .start-group__index {
  border-left-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

.page-start .start-trouble .start-group__title {
  color: var(--color-contrast-ink);
}

.page-start .start-trouble .start-group__meta {
  color: var(--color-contrast-accent);
}

.page-start .start-table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-md);
  background: var(--color-contrast-surface);
}

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

.page-start .start-table caption {
  padding: var(--space-2) var(--space-3);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
  text-align: left;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-contrast-accent);
}

.page-start .start-table th,
.page-start .start-table td {
  padding: var(--space-2) var(--space-3);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
  text-align: left;
  vertical-align: top;
  line-height: 1.55;
  color: var(--color-contrast-ink);
}

.page-start .start-table thead th {
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: 600;
  white-space: nowrap;
}

.page-start .start-table tbody tr:last-child th,
.page-start .start-table tbody tr:last-child td {
  border-bottom: 0;
}

.page-start .start-table tbody tr:hover {
  background: color-mix(in srgb, var(--color-contrast-accent) 12%, var(--color-contrast-surface));
}

.page-start .start-table__step {
  font-family: var(--font-mono);
  font-weight: 700;
  white-space: nowrap;
  color: var(--color-contrast-accent);
}

/* ---------- 下一步入口 ---------- */

.page-start .start-next__title {
  margin: 0 0 var(--space-2);
  color: var(--color-ink);
}

.page-start .start-next__lede {
  margin: 0 0 var(--space-6);
  color: var(--color-ink-soft);
}

.page-start .start-next__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-2);
}

.page-start .start-next__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-rows: auto auto;
  column-gap: var(--space-3);
  row-gap: var(--space-1);
  padding: var(--space-3);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface-alt);
  text-decoration: none;
  transition: border-color 180ms ease, transform 180ms ease, background-color 180ms ease;
}

.page-start .start-next__item:hover {
  border-color: color-mix(in srgb, var(--color-primary) 70%, transparent);
  background: var(--color-surface-deep);
  transform: translateY(-2px);
}

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

.page-start .start-next__num {
  grid-row: 1 / span 2;
  align-self: start;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 700;
  line-height: 1.1;
  color: var(--color-primary);
}

.page-start .start-next__name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-ink);
}

.page-start .start-next__desc {
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-ink-soft);
}

.page-start .start-footnote {
  margin: var(--space-6) 0 0;
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

/* ---------- 响应式 ---------- */

@media (min-width: 700px) {
  .page-start .start-step {
    grid-template-columns: var(--space-6) minmax(0, 1fr);
    gap: var(--space-3);
  }

  .page-start .start-step::after {
    left: calc(var(--space-3) - 0.5px);
  }

  .page-start .start-next__grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: var(--space-3);
  }

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

@media (min-width: 900px) {
  .page-start .start-hero {
    padding-top: var(--section-y);
  }

  .page-start .start-hero__split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: var(--space-6);
    align-items: start;
  }

  .page-start .start-hero__title {
    max-width: 100%;
  }

  .page-start .start-hero__figure img {
    aspect-ratio: 16 / 9;
  }

  .page-start .start-track {
    flex-direction: column;
    flex-wrap: nowrap;
    gap: 0;
    margin-bottom: var(--space-4);
    padding-left: var(--space-4);
    padding-bottom: 0;
    border-left: var(--border-thin) solid var(--color-line);
    overflow: visible;
  }

  .page-start .start-track__item {
    position: relative;
  }

  .page-start .start-track__item::before {
    content: "";
    position: absolute;
    left: calc(-1 * var(--space-4));
    top: 50%;
    width: 8px;
    height: 8px;
    transform: translate(-50%, -50%);
    border: var(--border-thin) solid var(--color-line);
    border-radius: var(--radius-pill);
    background: var(--color-surface-alt);
    transition: background-color 180ms ease, border-color 180ms ease;
  }

  .page-start .start-track__item:hover::before {
    background: var(--color-accent);
    border-color: var(--color-accent);
  }

  .page-start .start-track__link {
    display: flex;
    padding: var(--space-1) 0;
    border: 0;
    border-radius: 0;
    background: transparent;
    font-size: var(--text-base);
    white-space: normal;
  }

  .page-start .start-track__link:hover {
    border-color: transparent;
    color: var(--color-ink);
  }

  .page-start .start-hero__stats {
    gap: var(--space-4);
    padding-top: 0;
    padding-left: var(--space-4);
    border-top: 0;
    border-left: var(--border-thin) solid var(--color-line);
  }

  .page-start .start-narrow-figure {
    margin-left: auto;
    margin-right: 0;
  }

  .page-start .start-group--narrow .start-steps {
    max-width: 78%;
  }
}

@media (min-width: 1120px) {
  .page-start .start-group--narrow .start-steps {
    max-width: 72%;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-start .start-step__fold,
  .page-start .start-step__num,
  .page-start .start-next__item,
  .page-start .start-track__link {
    transition: none;
  }

  .page-start .start-next__item:hover {
    transform: none;
  }
}