.page-about {
  --about-rail: 236px;
  background: var(--ink-900);
  color: var(--text-primary);
  font-family: var(--font-body);
}

/* ---------- 首屏框景 ---------- */

.page-about .about-hero {
  position: relative;
  isolation: isolate;
  border-bottom: 1px solid var(--grid-line);
  background:
    radial-gradient(120% 90% at 14% 0%, rgba(18, 48, 39, .85) 0%, rgba(6, 19, 15, 0) 64%),
    var(--ink-900);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background-image:
    repeating-linear-gradient(90deg, rgba(30, 66, 55, .5) 0 1px, transparent 1px 96px),
    repeating-linear-gradient(0deg, rgba(30, 66, 55, .32) 0 1px, transparent 1px 96px);
  -webkit-mask-image: linear-gradient(180deg, #000 0%, transparent 86%);
  mask-image: linear-gradient(180deg, #000 0%, transparent 86%);
}

.page-about .about-hero__inner {
  padding-block: clamp(36px, 6vw, 88px) clamp(32px, 5vw, 64px);
}

.page-about .about-hero__crumbs {
  margin-bottom: clamp(20px, 3vw, 36px);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.page-about .breadcrumbs a {
  color: var(--text-muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .breadcrumbs a:hover,
.page-about .breadcrumbs a:focus-visible {
  color: var(--gold-300);
  border-bottom-color: var(--gold-300);
}

.page-about .about-hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 18px;
  color: var(--gold-500);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
}

.page-about .about-hero__eyebrow::before {
  content: "";
  width: 28px;
  height: 2px;
  background: var(--gold-500);
}

.page-about .about-hero__title {
  margin: 0 0 clamp(18px, 2.4vw, 26px);
  max-width: 20ch;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(32px, 6vw, 76px);
  line-height: 1.08;
  letter-spacing: -.02em;
  color: var(--text-primary);
  overflow-wrap: break-word;
}

.page-about .about-hero__lead {
  max-width: 42em;
  margin: 0;
  font-size: clamp(15px, 1.1vw, 17px);
  line-height: 1.9;
  color: var(--text-primary);
}

.page-about .about-hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 14px clamp(24px, 5vw, 56px);
  margin: clamp(28px, 4vw, 44px) 0 0;
  padding-top: 20px;
  border-top: 1px solid var(--grid-line);
}

.page-about .about-hero__meta-item {
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.page-about .about-hero__meta-item dt {
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--text-muted);
}

.page-about .about-hero__meta-item dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 18px;
  color: var(--gold-300);
}

/* ---------- 主体骨架：左目录 + 右章节流 ---------- */

.page-about .about-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 4vw, 48px);
  padding-top: clamp(32px, 5vw, 72px);
  padding-bottom: clamp(32px, 5vw, 72px);
}

.page-about .about-index {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 0 0 8px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

.page-about .about-index::-webkit-scrollbar {
  display: none;
}

.page-about .about-index__title {
  display: none;
}

.page-about .about-index__link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  flex: 0 0 auto;
  padding: 8px 12px;
  border: 1px solid var(--grid-line);
  color: var(--text-muted);
  font-size: 13px;
  line-height: 1.4;
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .about-index__link:hover,
.page-about .about-index__link:focus-visible,
.page-about .about-index__link[data-active="true"] {
  color: var(--gold-300);
  border-color: var(--gold-500);
  background: rgba(200, 162, 80, .08);
}

.page-about .about-index__num {
  font-size: 11px;
  letter-spacing: .06em;
  color: var(--gold-500);
}

/* ---------- 章节通用 ---------- */

.page-about .about-chap {
  padding-block: clamp(30px, 5vw, 60px);
  border-top: 1px solid var(--grid-line);
  scroll-margin-top: calc(var(--header-h, 72px) + 24px);
}

.page-about .about-chap:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .about-chap__num {
  width: max-content;
  margin: 0 0 12px;
  padding-bottom: 6px;
  font-family: var(--font-mono);
  font-size: clamp(28px, 4.2vw, 48px);
  font-weight: 500;
  line-height: 1;
  letter-spacing: -.04em;
  color: var(--gold-500);
  border-bottom: 2px solid var(--gold-500);
}

.page-about .about-chap__body {
  min-width: 0;
}

.page-about .about-chap__title {
  margin: 0 0 clamp(12px, 1.8vw, 18px);
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(23px, 3vw, 38px);
  line-height: 1.16;
  letter-spacing: -.02em;
  color: var(--text-primary);
}

.page-about .about-chap__lead {
  max-width: 40em;
  margin: 0 0 clamp(20px, 3vw, 32px);
  font-size: clamp(15px, 1.1vw, 16.5px);
  line-height: 1.9;
  color: var(--text-primary);
}

.page-about .about-note {
  max-width: 46em;
  margin: clamp(18px, 2.4vw, 26px) 0 0;
  padding-left: 14px;
  border-left: 1px solid var(--gold-500);
  font-size: 13px;
  line-height: 1.8;
  color: var(--text-muted);
}

.page-about .about-note a {
  color: var(--gold-300);
  text-decoration: none;
  border-bottom: 1px solid rgba(200, 162, 80, .45);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .about-note a:hover,
.page-about .about-note a:focus-visible {
  color: var(--gold-500);
  border-bottom-color: var(--gold-500);
}

.page-about .about-chap__cta {
  margin: clamp(18px, 2.4vw, 26px) 0 0;
}

/* ---------- 图片容器适配 ---------- */

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

/* ---------- 01 三条内容线 ---------- */

.page-about .about-lines {
  display: grid;
  gap: clamp(16px, 2.2vw, 22px);
}

.page-about .about-line {
  padding: 4px 0 4px 18px;
  border-left: 2px solid var(--grid-line);
  transition: border-color var(--dur) var(--ease);
}

.page-about .about-line:hover {
  border-left-color: var(--gold-500);
}

.page-about .about-line__title {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(17px, 1.4vw, 20px);
  line-height: 1.42;
  letter-spacing: -.01em;
  color: var(--gold-300);
}

.page-about .about-line__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-primary);
}

/* ---------- 02 数据来源 ---------- */

.page-about .about-split {
  display: grid;
  gap: clamp(20px, 3vw, 36px);
}

.page-about .about-split__figure {
  margin: 0;
  align-self: start;
}

.page-about .about-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: clamp(16px, 2.4vw, 24px);
}

.page-about .about-step {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 14px;
  padding-top: 14px;
  border-top: 1px solid var(--grid-line);
}

.page-about .about-step__num {
  padding-top: 3px;
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--signal-orange);
}

.page-about .about-step__title {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(16px, 1.3vw, 18px);
  line-height: 1.45;
  color: var(--text-primary);
}

.page-about .about-step p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-primary);
}

/* ---------- 03 三类使用者 ---------- */

.page-about .about-who {
  display: grid;
  gap: clamp(20px, 2.6vw, 28px);
}

.page-about .about-who__item {
  position: relative;
  padding-top: 18px;
  border-top: 2px solid var(--ink-700);
}

.page-about .about-who__item::before {
  content: "";
  position: absolute;
  top: -2px;
  left: 0;
  width: 46px;
  height: 2px;
  background: var(--gold-500);
}

.page-about .about-who__tag {
  display: inline-block;
  margin: 0 0 12px;
}

.page-about .about-who__title {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(17px, 1.4vw, 20px);
  line-height: 1.45;
  color: var(--text-primary);
}

.page-about .about-who__item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-primary);
}

/* ---------- 04 团队 ---------- */

.page-about .about-team {
  display: grid;
  gap: clamp(14px, 2vw, 22px);
  margin-bottom: clamp(24px, 3.4vw, 38px);
}

.page-about .about-team__item {
  padding: clamp(16px, 2vw, 24px);
  background: var(--ink-800);
  border: 1px solid var(--grid-line);
  transition: transform var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .about-team__item:hover {
  transform: translateY(-2px);
  border-color: var(--gold-500);
}

.page-about .about-team__item h3 {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 17px;
  line-height: 1.45;
  color: var(--gold-300);
}

.page-about .about-team__item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-primary);
}

.page-about .about-wide-figure {
  margin: 0;
}

/* ---------- 05 版本时间轴 ---------- */

.page-about .about-timeline {
  margin-top: clamp(8px, 1.5vw, 16px);
}

.page-about .about-timeline__scale {
  display: block;
  width: 100%;
  height: 44px;
  margin-bottom: 2px;
}

.page-about .about-timeline__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: clamp(18px, 2.6vw, 28px);
}

.page-about .about-ver__item {
  position: relative;
  padding-top: 20px;
  border-top: 1px solid var(--grid-line);
}

.page-about .about-ver__item::before {
  content: "";
  position: absolute;
  top: -5px;
  left: 0;
  width: 9px;
  height: 9px;
  background: var(--ink-900);
  border: 2px solid var(--gold-500);
  transform: rotate(45deg);
}

.page-about .about-ver__item--current {
  border-top-color: var(--gold-500);
}

.page-about .about-ver__item--current::before {
  background: var(--gold-500);
  border-color: var(--gold-300);
}

.page-about .about-ver__tag {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 15px;
  letter-spacing: .1em;
  color: var(--signal-orange);
}

.page-about .about-ver__name {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(16px, 1.3vw, 18px);
  line-height: 1.45;
  color: var(--text-primary);
}

.page-about .about-ver__desc {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-primary);
}

/* ---------- 06 地区与备案 ---------- */

.page-about .about-region {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--grid-line);
}

.page-about .about-region li {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px 20px;
  padding: 14px 0;
  border-bottom: 1px solid var(--grid-line);
}

.page-about .about-region__k {
  min-width: 92px;
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--text-muted);
}

.page-about .about-region__v {
  font-size: 16px;
  color: var(--text-primary);
}

/* ---------- 收尾行动区 ---------- */

.page-about .about-cta {
  margin-top: clamp(16px, 3vw, 32px);
  border-top: 1px solid var(--grid-line);
  border-bottom: 1px solid var(--grid-line);
  background: linear-gradient(180deg, var(--ink-800) 0%, var(--ink-900) 100%);
}

.page-about .about-cta__inner {
  padding-block: clamp(36px, 5vw, 72px);
}

.page-about .about-cta__title {
  margin: 0 0 14px;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(23px, 3.2vw, 38px);
  line-height: 1.16;
  letter-spacing: -.02em;
  color: var(--text-primary);
}

.page-about .about-cta__text {
  max-width: 44em;
  margin: 0 0 clamp(20px, 3vw, 30px);
  font-size: 15px;
  line-height: 1.9;
  color: var(--text-primary);
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 桌面：左目录固定 ---------- */

@media (min-width: 760px) {
  .page-about .about-chap {
    display: grid;
    grid-template-columns: clamp(72px, 6vw, 104px) minmax(0, 1fr);
    gap: clamp(16px, 3vw, 40px);
    align-items: start;
  }
}

@media (min-width: 880px) {
  .page-about .about-lines {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: clamp(16px, 2.4vw, 28px);
  }

  .page-about .about-split {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
  }

  .page-about .about-who {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-team {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-timeline__list {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: clamp(18px, 2.4vw, 32px);
  }
}

@media (min-width: 1000px) {
  .page-about .about-shell {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: clamp(32px, 4vw, 72px);
    align-items: start;
  }

  .page-about .about-index {
    position: sticky;
    top: calc(var(--header-h, 72px) + 24px);
    display: block;
    overflow: visible;
    padding: 0;
    border-left: 1px solid var(--grid-line);
  }

  .page-about .about-index__title {
    display: block;
    margin: 0 0 14px;
    padding-left: 16px;
    font-family: var(--font-mono);
    font-size: 11px;
    letter-spacing: .14em;
    color: var(--text-muted);
  }

  .page-about .about-index__link {
    display: flex;
    margin-left: -1px;
    padding: 9px 12px 9px 15px;
    border: 0;
    border-left: 2px solid transparent;
    background: none;
    font-size: 14px;
  }

  .page-about .about-index__link:hover,
  .page-about .about-index__link:focus-visible,
  .page-about .about-index__link[data-active="true"] {
    border-left-color: var(--gold-500);
    color: var(--gold-300);
    background: linear-gradient(90deg, rgba(200, 162, 80, .12) 0%, rgba(200, 162, 80, 0) 88%);
  }

  .page-about .about-hero__title {
    max-width: 18ch;
  }
}

/* ---------- 窄屏保护 ---------- */

@media (max-width: 420px) {
  .page-about .about-step {
    grid-template-columns: 26px minmax(0, 1fr);
    gap: 10px;
  }

  .page-about .about-region__k {
    min-width: 100%;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition-duration: 1ms !important;
    animation-duration: 1ms !important;
  }
}