.page-about {
  --about-rail: 208px;
  --about-prose: 700px;
  --about-ink-soft: #3A342B;
  padding-bottom: clamp(56px, 8vw, 112px);
}

.page-about a:focus-visible,
.page-about button:focus-visible {
  outline: 2px solid var(--orange);
  outline-offset: 3px;
}

/* ---------- 页面头部 ---------- */
.page-about .about-head {
  position: relative;
  padding: clamp(18px, 3.6vw, 46px) 0 clamp(26px, 4vw, 42px);
  border-bottom: 2px solid var(--line-strong);
}

.page-about .about-head::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: -2px;
  width: min(300px, 42%);
  height: 6px;
  background: linear-gradient(90deg, transparent, var(--orange));
}

.page-about .about-head .eyebrow {
  margin: 16px 0 10px;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: .2em;
  color: var(--amber);
  text-transform: uppercase;
}

.page-about .about-head h1 {
  max-width: 24ch;
  margin: 0 0 18px;
  font-family: var(--serif);
  font-weight: 700;
  font-size: clamp(30px, 5vw, 54px);
  line-height: 1.18;
  letter-spacing: -.01em;
  color: var(--hot);
}

.page-about .about-lede {
  max-width: 62ch;
  margin: 0;
  font-size: clamp(16px, 1.6vw, 19px);
  line-height: 1.8;
  color: var(--bone);
}

.page-about .about-marks {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2px;
  margin: 30px 0 0;
  padding: 2px;
  list-style: none;
  background: var(--line-strong);
  border: 2px solid var(--line-strong);
  box-shadow: var(--shadow-hard-sm);
}

.page-about .about-marks li {
  display: grid;
  gap: 4px;
  padding: 14px 16px;
  background: var(--corridor);
}

.page-about .mark-k {
  font-size: 13px;
  letter-spacing: .06em;
  color: var(--rock);
}

.page-about .mark-v {
  font-family: var(--mono);
  font-size: clamp(20px, 2.6vw, 26px);
  color: var(--orange);
}

/* ---------- 主体骨架 ---------- */
.page-about .about-body {
  display: grid;
  gap: clamp(28px, 4vw, 52px);
  padding-top: clamp(30px, 5vw, 56px);
}

.page-about .about-toc {
  border-top: 2px solid var(--line);
  border-bottom: 2px solid var(--line);
  padding: 12px 0;
}

.page-about .toc-title {
  margin: 0 0 8px;
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: .2em;
  color: var(--moss);
  text-transform: uppercase;
}

.page-about .toc-list {
  display: flex;
  gap: 10px;
  margin: 0;
  padding: 0 0 4px;
  list-style: none;
  overflow-x: auto;
  counter-reset: toc;
  scrollbar-width: thin;
}

.page-about .toc-list li {
  flex: 0 0 auto;
  counter-increment: toc;
}

.page-about .toc-list a {
  display: block;
  padding: 7px 11px;
  border: 2px solid transparent;
  color: var(--bone);
  font-size: 14px;
  line-height: 1.5;
  text-decoration: none;
  white-space: nowrap;
  transition: border-color .25s var(--ease), background-color .25s var(--ease), color .25s var(--ease);
}

.page-about .toc-list a::before {
  content: counter(toc, decimal-leading-zero);
  margin-right: 8px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--moss);
}

.page-about .toc-list a:hover,
.page-about .toc-list a:focus-visible {
  border-color: var(--orange);
  background: var(--corridor);
  color: var(--hot);
}

.page-about .about-stream {
  display: grid;
  gap: clamp(48px, 7vw, 84px);
  max-width: var(--about-prose);
  min-width: 0;
}

/* ---------- 章节通用 ---------- */
.page-about .about-sec {
  scroll-margin-top: 92px;
  min-width: 0;
}

.page-about .sec-num {
  margin: 0;
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: .22em;
  color: var(--cyan);
}

.page-about .about-sec h2 {
  margin: 10px 0 18px;
  font-family: var(--serif);
  font-weight: 700;
  font-size: clamp(24px, 3.4vw, 34px);
  line-height: 1.3;
  color: var(--hot);
}

.page-about .about-sec p {
  margin: 0 0 16px;
  font-size: 16.5px;
  line-height: 1.85;
  color: var(--bone);
}

.page-about .about-sec p:last-child {
  margin-bottom: 0;
}

.page-about .about-sec a {
  color: var(--cyan);
  text-underline-offset: 3px;
}

.page-about .about-note {
  margin: 24px 0 6px;
  padding: 16px 18px;
  background: rgba(180, 85, 58, .16);
  border-left: 4px solid var(--clay);
  box-shadow: var(--shadow-hard-sm);
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--bone);
}

.page-about .note-label {
  display: block;
  margin-bottom: 6px;
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: .18em;
  color: var(--clay);
  text-transform: uppercase;
}

/* ---------- 图片 ---------- */
.page-about .about-figure {
  margin: 28px 0 26px;
}

.page-about .about-figure--lead {
  margin-top: 6px;
}

.page-about .about-figure figcaption {
  margin-top: 10px;
  padding-left: 12px;
  border-left: 3px solid var(--moss);
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--rock);
}

.page-about .media {
  overflow: hidden;
  border: 2px solid var(--line-strong);
  background: var(--corridor);
  box-shadow: var(--shadow-hard);
}

.page-about .media img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
}

/* ---------- 时间轴 ---------- */
.page-about .timeline {
  margin: 30px 0 0;
  padding: 0 0 0 26px;
  list-style: none;
  border-left: 2px solid var(--line-strong);
}

.page-about .tl-item {
  position: relative;
  padding-bottom: 30px;
}

.page-about .tl-item:last-child {
  padding-bottom: 0;
}

.page-about .tl-item::before {
  content: "";
  position: absolute;
  left: -33px;
  top: 7px;
  box-sizing: border-box;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--night);
  border: 3px solid var(--clay);
  transition: background-color .45s var(--ease), border-color .45s var(--ease), box-shadow .45s var(--ease);
}

.page-about .tl-item.is-in::before {
  background: var(--orange);
  border-color: var(--orange);
  box-shadow: 0 0 0 6px rgba(255, 122, 26, .18);
}

.page-about .tl-tag {
  display: block;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--cyan);
}

.page-about .tl-title {
  margin: 5px 0 7px;
  font-family: var(--serif);
  font-weight: 600;
  font-size: 19px;
  line-height: 1.4;
  color: var(--hot);
}

.page-about .tl-item p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.8;
  color: rgba(242, 237, 227, .84);
}

/* ---------- 数字里程碑 ---------- */
.page-about .about-sec--miles {
  padding: clamp(20px, 3.4vw, 32px);
  background: linear-gradient(150deg, var(--corridor), var(--night) 78%);
  border: 2px solid var(--line-strong);
  border-top: 6px solid var(--moss);
  box-shadow: var(--shadow-hard);
}

.page-about .mile-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px 18px;
  margin-top: 22px;
}

.page-about .mile {
  display: grid;
  gap: 6px;
}

.page-about .mile .stat-value {
  font-family: var(--mono);
  font-size: clamp(30px, 5.4vw, 44px);
  line-height: 1;
  color: var(--orange);
}

.page-about .mile .stat-label {
  font-size: 13.5px;
  line-height: 1.65;
  color: var(--rock);
}

/* ---------- 米白规矩带 ---------- */
.page-about .about-sec--panel {
  padding: clamp(24px, 4vw, 42px);
  background: var(--bone);
  border-left: 8px solid var(--moss);
  box-shadow: var(--shadow-hard);
}

.page-about .about-sec--panel .sec-num {
  color: var(--clay);
}

.page-about .about-sec--panel h2 {
  color: var(--ink);
}

.page-about .about-sec--panel p {
  color: var(--about-ink-soft);
}

.page-about .about-sec--panel a {
  color: #8A3A1E;
}

.page-about .rule-list {
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
  counter-reset: rule;
}

.page-about .rule-list li {
  position: relative;
  counter-increment: rule;
  padding: 20px 0 20px 56px;
  border-top: 2px solid rgba(20, 16, 12, .18);
}

.page-about .rule-list li:first-child {
  padding-top: 8px;
  border-top: 0;
}

.page-about .rule-list li::before {
  content: counter(rule, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 22px;
  font-family: var(--mono);
  font-size: 22px;
  line-height: 1;
  color: var(--clay);
}

.page-about .rule-list li:first-child::before {
  top: 10px;
}

.page-about .rule-list h3 {
  margin: 0 0 8px;
  font-family: var(--serif);
  font-weight: 600;
  font-size: 18px;
  line-height: 1.45;
  color: var(--ink);
}

.page-about .rule-list p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--about-ink-soft);
}

/* ---------- 行动按钮 ---------- */
.page-about .about-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .about-marks {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .mile-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 960px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-toc {
    position: sticky;
    top: 96px;
    border-top: 0;
    border-bottom: 0;
    border-left: 2px solid var(--line);
    padding: 4px 0 4px 16px;
  }

  .page-about .toc-list {
    display: block;
    overflow: visible;
    padding: 0;
  }

  .page-about .toc-list li {
    display: block;
  }

  .page-about .toc-list a {
    white-space: normal;
    padding: 8px 10px;
  }
}

@media (min-width: 1180px) {
  .page-about .about-stream {
    max-width: calc(var(--about-prose) + 40px);
  }
}