.page-start {
  --start-rail: 108px;
  --start-meta: 240px;
  --start-step-num: clamp(30px, 4.2vw, 48px);
}

/* ---------- 首屏封面 ---------- */
.page-start .start-cover {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  padding: var(--space-4) 0 var(--space-8);
  border-bottom: var(--border-thick) solid var(--color-contrast-line);
}

.page-start .start-cover__backdrop {
  position: absolute;
  inset: 0;
  z-index: -1;
}

.page-start .start-cover__backdrop img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center 32%;
  filter: grayscale(1) sepia(0.48) hue-rotate(-14deg) brightness(0.7) contrast(1.14);
}

.page-start .start-cover__backdrop::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
}

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

.page-start .start-cover__crumb {
  color: var(--color-contrast-ink);
  opacity: 0.72;
  margin-bottom: var(--space-4);
}

.page-start .start-cover__crumb a {
  color: var(--color-contrast-accent);
  text-decoration: none;
}

.page-start .start-cover__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4);
}

.page-start .start-cover__head {
  text-align: center;
}

.page-start .start-cover__title {
  margin: 0 auto;
  max-width: 16ch;
  color: var(--color-contrast-ink);
  text-wrap: balance;
}

.page-start .start-cover__lede {
  margin: var(--space-3) auto 0;
  max-width: 54ch;
  color: var(--color-contrast-ink);
  opacity: 0.86;
}

/* 三段标签 */
.page-start .start-cover__rail {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.page-start .start-cover__rail li {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 10px;
  border: var(--border-thin) solid var(--color-contrast-line);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}

.page-start .start-cover__rail li span {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-contrast-accent);
}

/* 十格刻度 */
.page-start .start-scale {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(10, minmax(0, 1fr));
  gap: 2px;
}

.page-start .start-scale a {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  padding: 6px 0 2px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-contrast-ink);
  text-decoration: none;
}

.page-start .start-scale a::before {
  content: "";
  width: 2px;
  height: 22px;
  background: var(--color-contrast-line);
  transition: background 0.2s ease;
}

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

.page-start .start-scale a:hover,
.page-start .start-scale a:focus-visible {
  color: var(--color-contrast-accent);
}

/* 总耗时 */
.page-start .start-cover__meta {
  border: var(--border-thin) solid var(--color-contrast-line);
  padding: var(--space-3);
  display: grid;
  gap: var(--space-2);
  align-content: start;
}

.page-start .start-cover__total {
  display: flex;
  align-items: baseline;
  gap: 6px;
  font-family: var(--font-mono);
}

.page-start .start-cover__total-value {
  font-size: var(--text-3xl);
  line-height: 1;
  font-weight: var(--weight-heading);
  color: var(--color-contrast-accent);
}

.page-start .start-cover__total-unit {
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
}

.page-start .start-cover__total-label {
  margin: 0;
  font-size: var(--text-xs);
  color: var(--color-contrast-ink);
  opacity: 0.7;
  letter-spacing: 0.06em;
}

.page-start .start-cover__splits {
  list-style: none;
  margin: 0;
  padding: var(--space-2) 0 0;
  border-top: var(--border-thin) solid var(--color-contrast-line);
  display: grid;
  gap: 6px;
}

.page-start .start-cover__splits li {
  display: flex;
  align-items: baseline;
  gap: var(--space-1);
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
}

.page-start .start-cover__splits b {
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  color: var(--color-contrast-accent);
  min-width: 2.2ch;
}

@media (min-width: 880px) {
  .page-start .start-cover {
    padding: var(--space-6) 0 var(--space-8);
  }

  .page-start .start-cover__grid {
    grid-template-columns: var(--start-rail) minmax(0, 1fr) var(--start-meta);
    grid-template-areas:
      "text text text"
      "rail scale meta";
    column-gap: var(--space-4);
    row-gap: var(--space-6);
    align-items: start;
  }

  .page-start .start-cover__head {
    grid-area: text;
  }

  .page-start .start-cover__rail {
    grid-area: rail;
    flex-direction: column;
    flex-wrap: nowrap;
    gap: var(--space-2);
  }

  .page-start .start-cover__rail li {
    writing-mode: vertical-rl;
    text-orientation: upright;
    padding: 12px 7px;
    letter-spacing: 0.2em;
    justify-content: center;
  }

  .page-start .start-cover__scale {
    grid-area: scale;
    align-self: end;
  }

  .page-start .start-cover__meta {
    grid-area: meta;
  }
}

/* ---------- 分段与步骤 ---------- */
.page-start .start-part--a {
  background: var(--color-surface);
}

.page-start .start-part--b {
  background: var(--color-surface-alt);
}

.page-start .start-part--c {
  background: var(--color-surface-deep);
}

.page-start .start-parthead {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4);
  align-items: end;
  margin-bottom: var(--space-6);
}

.page-start .start-parthead--text {
  display: block;
}

.page-start .start-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-start .start-parthead__figure {
  aspect-ratio: 3 / 2;
  margin: 0;
}

.page-start .start-parthead__figure.start-sidefigure {
  aspect-ratio: 10 / 7;
}

@media (min-width: 880px) {
  .page-start .start-parthead {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: var(--space-6);
  }
}

.page-start .start-track {
  display: grid;
  border-top: var(--border-thick) solid var(--color-primary);
}

.page-start .start-step {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-2);
  padding: var(--space-3) 0;
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-start .start-step__index {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.page-start .start-step__num {
  font-family: var(--font-mono);
  font-size: var(--start-step-num);
  line-height: 0.9;
  font-weight: var(--weight-heading);
  letter-spacing: -0.02em;
  color: var(--color-primary);
}

.page-start .start-step__title {
  margin: 0 0 var(--space-1);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

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

.page-start .start-step__linkline {
  margin-top: var(--space-2) !important;
}

.page-start .start-step__linkline a {
  font-size: var(--text-sm);
  color: var(--color-accent);
  text-decoration: none;
  border-bottom: var(--border-thin) solid var(--color-accent);
  padding-bottom: 2px;
}

.page-start .start-step__linkline a:hover,
.page-start .start-step__linkline a:focus-visible {
  color: var(--color-focus);
  border-bottom-color: var(--color-focus);
}

.page-start .start-step__gain {
  border-top: var(--border-thin) solid var(--color-line);
  padding-top: var(--space-2);
}

.page-start .start-step__gain-label {
  margin: 0 0 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-accent);
}

.page-start .start-step__gain p {
  margin: 0;
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

@media (min-width: 880px) {
  .page-start .start-step {
    grid-template-columns: 92px minmax(0, 1fr) minmax(0, 300px);
    gap: var(--space-4);
    padding: var(--space-4) 0;
    align-items: start;
  }

  .page-start .start-step__index {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-2);
  }

  .page-start .start-step__gain {
    border-top: 0;
    border-left: var(--border-thin) solid var(--color-line);
    padding-top: 0;
    padding-left: var(--space-3);
    min-height: 100%;
  }
}

/* ---------- 卡点速查 ---------- */
.page-start .start-blockers {
  background: var(--color-surface-deep);
}

.page-start .start-faq {
  margin: 0;
  display: grid;
  border-top: var(--border-thick) solid var(--color-primary);
}

.page-start .start-faq__row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
  padding: var(--space-3) 0;
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-start .start-faq__row dt {
  display: flex;
  align-items: baseline;
  gap: var(--space-1);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.page-start .start-faq__mark {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-accent);
  flex: none;
}

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

@media (min-width: 880px) {
  .page-start .start-faq__row {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    gap: var(--space-4);
    padding: var(--space-4) 0;
    align-items: start;
  }

  .page-start .start-faq__row dd {
    padding-left: var(--space-3);
    border-left: var(--border-thin) solid var(--color-line);
  }
}

/* ---------- 下一步入口 ---------- */
.page-start .start-exit__head {
  margin-bottom: var(--space-6);
}

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

.page-start .start-exit__link {
  display: grid;
  gap: var(--space-2);
  align-content: start;
  padding: var(--space-3);
  border: var(--border-thin) solid var(--color-contrast-line);
  color: var(--color-contrast-ink);
  text-decoration: none;
  transition: border-color 0.2s ease, background 0.2s ease;
}

.page-start .start-exit__link:hover,
.page-start .start-exit__link:focus-visible {
  border-color: var(--color-contrast-accent);
  background: color-mix(in srgb, var(--color-contrast-accent) 14%, transparent);
}

.page-start .start-exit__linknum {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-contrast-accent);
}

.page-start .start-exit__link h3 {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}

.page-start .start-exit__link p {
  margin: 0;
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-contrast-ink);
  opacity: 0.78;
}

.page-start .start-exit__arrow {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-contrast-accent);
  border-bottom: var(--border-thin) solid var(--color-contrast-accent);
  justify-self: start;
  padding-bottom: 2px;
}

@media (min-width: 880px) {
  .page-start .start-exit__links {
    grid-template-columns: 1.5fr 1fr 1fr;
    gap: var(--space-3);
  }

  .page-start .start-exit__link--wide {
    grid-row: span 1;
  }
}