.page-about {
  --about-rail-w: 92px;
  --about-hairline: 1px solid var(--line);
  display: block;
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumbs {
  padding-top: clamp(18px, 3vw, 32px);
}

/* ---------- 封面 ---------- */
.page-about .about-cover {
  position: relative;
  margin-top: clamp(20px, 3vw, 34px);
  padding: clamp(36px, 6vw, 88px) 0 clamp(32px, 5vw, 64px);
  border-top: var(--about-hairline);
  border-bottom: var(--about-hairline);
  overflow: hidden;
}

.page-about .about-cover::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(29, 74, 102, .34) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(29, 74, 102, .2) 1px, transparent 1px);
  background-size: 72px 72px;
  opacity: .55;
  pointer-events: none;
}

.page-about .about-cover__inner {
  position: relative;
  z-index: 1;
}

.page-about .about-cover__eyebrow {
  margin: 0 0 clamp(14px, 2vw, 22px);
  font-family: var(--font-mono);
  font-size: var(--step--2);
  letter-spacing: .18em;
  color: var(--gold);
}

.page-about .about-cover__title {
  margin: 0;
  max-width: 16em;
  font-family: var(--font-display);
  font-size: clamp(30px, 5.4vw, 56px);
  font-weight: 700;
  line-height: 1.22;
  letter-spacing: -0.02em;
  color: var(--text);
}

.page-about .about-cover__lede {
  margin: clamp(18px, 2.6vw, 30px) 0 0;
  max-width: 34em;
  font-size: var(--step-0);
  line-height: 1.9;
  color: var(--text-dim);
}

.page-about .about-cover__index {
  display: grid;
  gap: 1px;
  margin-top: clamp(26px, 4vw, 44px);
  background: var(--line);
  border: var(--about-hairline);
}

@media (min-width: 720px) {
  .page-about .about-cover__index {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.page-about .about-index-link {
  position: relative;
  display: grid;
  gap: 6px;
  padding: clamp(18px, 2.4vw, 26px);
  background: var(--ink-800);
  text-decoration: none;
  transition: background var(--dur) var(--ease);
}

.page-about .about-index-link:hover {
  background: var(--ink-700);
}

.page-about .about-index-link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: var(--gold-light);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur) var(--ease);
}

.page-about .about-index-link:hover::after,
.page-about .about-index-link:focus-visible::after {
  transform: scaleX(1);
}

.page-about .about-index-link:focus-visible {
  outline: 2px solid var(--gold-light);
  outline-offset: -2px;
}

.page-about .about-index-link__num {
  font-family: var(--font-mono);
  font-size: var(--step--2);
  letter-spacing: .16em;
  color: var(--brass);
}

.page-about .about-index-link__label {
  font-family: var(--font-display);
  font-size: var(--step-1);
  color: var(--gold-light);
}

.page-about .about-index-link__note {
  font-size: var(--step--1);
  line-height: 1.7;
  color: var(--text-mute);
}

.page-about .about-facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: clamp(28px, 4vw, 46px) 0 0;
  padding: 0;
  background: var(--line);
  border-top: var(--about-hairline);
  border-bottom: var(--about-hairline);
}

@media (min-width: 840px) {
  .page-about .about-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .about-facts__item {
  padding: clamp(16px, 2vw, 22px) clamp(12px, 1.6vw, 20px);
  background: var(--ink-900);
}

.page-about .about-facts dt {
  margin-bottom: 8px;
  font-size: var(--step--2);
  letter-spacing: .14em;
  color: var(--text-mute);
}

.page-about .about-facts dd {
  margin: 0;
  font-size: var(--step--1);
  color: var(--text-dim);
}

.page-about .about-facts .num {
  margin-right: 6px;
  font-family: var(--font-mono);
  font-size: var(--step-2);
  color: var(--gold);
}

/* ---------- 主体长开本 ---------- */
.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(22px, 4vw, 44px);
  padding-top: clamp(36px, 6vw, 76px);
  padding-bottom: clamp(48px, 8vw, 110px);
}

@media (min-width: 1000px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: clamp(32px, 5vw, 76px);
  }
}

/* ---------- 年份刻度 ---------- */
.page-about .about-rail {
  position: relative;
}

@media (min-width: 1000px) {
  .page-about .about-rail {
    position: sticky;
    top: 132px;
    align-self: start;
  }
}

.page-about .about-rail__title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: var(--step--2);
  letter-spacing: .2em;
  color: var(--text-mute);
}

.page-about .about-rail__list {
  position: relative;
  display: flex;
  gap: clamp(20px, 4vw, 34px);
  margin: 0;
  padding: 0 0 10px;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-rail__list::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 1px;
  background: var(--line-strong);
}

@media (min-width: 1000px) {
  .page-about .about-rail__list {
    flex-direction: column;
    gap: clamp(26px, 5vh, 54px);
    padding: 0 0 0 16px;
    overflow: visible;
  }

  .page-about .about-rail__list::before {
    left: 0;
    right: auto;
    top: 0;
    bottom: 0;
    width: 1px;
    height: auto;
  }
}

.page-about .about-rail__item {
  position: relative;
  flex: 0 0 auto;
  padding-top: 16px;
}

.page-about .about-rail__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 1px;
  height: 12px;
  background: var(--ink-600);
  transition: background var(--dur) var(--ease), height var(--dur) var(--ease);
}

@media (min-width: 1000px) {
  .page-about .about-rail__item {
    padding-top: 0;
  }

  .page-about .about-rail__item::before {
    left: -16px;
    top: .62em;
    width: 16px;
    height: 1px;
  }
}

.page-about .about-rail__item a {
  display: block;
  text-decoration: none;
}

.page-about .about-rail__item:hover::before {
  background: var(--gold);
}

.page-about .about-rail__item:hover::before,
.page-about .about-rail__item:focus-within::before {
  background: var(--gold-light);
}

.page-about .about-rail__year {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  letter-spacing: .06em;
  color: var(--text-mute);
  transition: color var(--dur) var(--ease);
}

.page-about .about-rail__item:hover .about-rail__year,
.page-about .about-rail__item:focus-within .about-rail__year {
  color: var(--gold-light);
}

.page-about .about-rail__item a:focus-visible {
  outline: 2px solid var(--gold-light);
  outline-offset: 4px;
}

/* ---------- 章节 ---------- */
.page-about .about-flow {
  min-width: 0;
}

.page-about .about-chapter {
  position: relative;
  padding-top: clamp(28px, 4vw, 46px);
  border-top: var(--about-hairline);
}

.page-about .about-chapter + .about-chapter {
  margin-top: clamp(52px, 9vw, 112px);
}

.page-about .about-chapter__badge {
  position: absolute;
  top: clamp(28px, 4vw, 46px);
  right: 0;
  z-index: 2;
  text-align: right;
}

.page-about .about-chapter__tag {
  display: inline-block;
  padding: 4px 10px;
  border: 1px solid var(--line-strong);
  background: var(--ink-900);
  font-family: var(--font-mono);
  font-size: var(--step--2);
  letter-spacing: .12em;
  color: var(--brass);
  cursor: default;
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .about-chapter__badge:hover .about-chapter__tag,
.page-about .about-chapter__badge:focus-within .about-chapter__tag {
  border-color: var(--gold-light);
  color: var(--gold-light);
}

.page-about .about-chapter__tag:focus-visible {
  outline: 2px solid var(--gold-light);
  outline-offset: 2px;
}

.page-about .about-chapter__tip {
  position: absolute;
  right: 0;
  top: calc(100% + 8px);
  width: min(250px, 62vw);
  margin: 0;
  padding: 10px 12px;
  border: 1px solid var(--line-strong);
  background: var(--ink-800);
  font-size: var(--step--2);
  line-height: 1.7;
  color: var(--text-dim);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-4px);
  transition: opacity var(--dur) var(--ease), transform var(--dur) var(--ease), visibility var(--dur) linear;
}

.page-about .about-chapter__badge:hover .about-chapter__tip,
.page-about .about-chapter__badge:focus-within .about-chapter__tip {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.page-about .about-chapter__eyebrow {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: var(--step--2);
  letter-spacing: .2em;
  color: var(--brass);
  transition: color var(--dur) var(--ease);
}

.page-about .about-chapter__eyebrow::before {
  content: "";
  flex: 0 0 auto;
  width: clamp(22px, 5vw, 56px);
  height: 1px;
  background: var(--brass);
  transition: background var(--dur) var(--ease);
}

.page-about .about-chapter[data-active="true"] .about-chapter__eyebrow {
  color: var(--gold-light);
}

.page-about .about-chapter[data-active="true"] .about-chapter__eyebrow::before {
  background: var(--gold);
}

.page-about .about-chapter__title {
  margin: 0;
  max-width: 17em;
  font-family: var(--font-display);
  font-size: clamp(24px, 3.6vw, 32px);
  font-weight: 700;
  line-height: 1.35;
  letter-spacing: -0.01em;
  color: var(--text);
}

.page-about .about-chapter__lede {
  margin: clamp(16px, 2vw, 22px) 0 0;
  max-width: 34em;
  font-size: var(--step-0);
  line-height: 1.9;
  color: var(--text-dim);
}

.page-about .about-text {
  max-width: 36em;
}

.page-about .about-text p {
  margin: 0 0 1.1em;
  font-size: var(--step-0);
  line-height: 1.9;
  color: var(--text-dim);
}

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

.page-about .about-text--foot {
  margin-top: clamp(22px, 3vw, 34px);
}

/* ---------- 章节 01 ---------- */
.page-about .about-open {
  display: grid;
  gap: clamp(20px, 3vw, 34px);
  margin-top: clamp(22px, 3vw, 34px);
}

@media (min-width: 860px) {
  .page-about .about-open {
    grid-template-columns: minmax(0, .62fr) minmax(0, 1fr);
    align-items: start;
    gap: clamp(24px, 3.4vw, 44px);
  }
}

.page-about .about-open__media {
  margin: 0;
}

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

.page-about .about-timeline {
  margin: clamp(28px, 4vw, 46px) 0 0;
  padding: 0;
  list-style: none;
  border-top: var(--about-hairline);
}

.page-about .about-timeline__item {
  display: grid;
  gap: 6px;
  padding: clamp(14px, 2vw, 20px) 0;
  border-bottom: var(--about-hairline);
}

@media (min-width: 620px) {
  .page-about .about-timeline__item {
    grid-template-columns: 88px minmax(0, 1fr);
    gap: 24px;
    align-items: baseline;
  }
}

.page-about .about-timeline__year {
  font-family: var(--font-mono);
  font-size: var(--step-1);
  letter-spacing: .02em;
  color: var(--gold);
}

.page-about .about-timeline__title {
  margin: 0 0 4px;
  font-size: var(--step-0);
  font-weight: 600;
  color: var(--text);
}

.page-about .about-timeline__item p {
  max-width: 40em;
  margin: 0;
  font-size: var(--step--1);
  line-height: 1.85;
  color: var(--text-mute);
}

/* ---------- 章节 02 ---------- */
.page-about .about-halls-media {
  margin: clamp(24px, 3.4vw, 38px) 0 0;
}

.page-about .about-standards {
  display: grid;
  gap: 1px;
  margin-top: clamp(24px, 3vw, 38px);
  background: var(--line);
  border: var(--about-hairline);
}

@media (min-width: 760px) {
  .page-about .about-standards {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.page-about .about-standards__item {
  padding: clamp(18px, 2.2vw, 26px);
  background: var(--ink-800);
}

.page-about .about-standards__num {
  display: block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-size: var(--step--2);
  letter-spacing: .16em;
  color: var(--brass);
}

.page-about .about-standards__title {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-size: var(--step-1);
  font-weight: 700;
  color: var(--gold-light);
}

.page-about .about-standards__item p {
  margin: 0;
  font-size: var(--step--1);
  line-height: 1.85;
  color: var(--text-dim);
}

.page-about .about-halls {
  display: grid;
  gap: 1px;
  margin: clamp(26px, 3.4vw, 42px) 0 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border-top: var(--about-hairline);
  border-bottom: var(--about-hairline);
}

@media (min-width: 700px) {
  .page-about .about-halls {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1120px) {
  .page-about .about-halls {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.page-about .about-halls__item {
  display: grid;
  gap: 6px;
  align-content: start;
  padding: clamp(16px, 2vw, 22px);
  background: var(--ink-900);
  transition: background var(--dur) var(--ease);
}

.page-about .about-halls__item:hover {
  background: var(--ink-800);
}

.page-about .about-halls__num {
  font-family: var(--font-mono);
  font-size: var(--step--2);
  letter-spacing: .14em;
  color: var(--brass);
}

.page-about .about-halls__name {
  font-size: var(--step-0);
  font-weight: 600;
  color: var(--text);
}

.page-about .about-halls__desc {
  margin: 0;
  font-size: var(--step--1);
  line-height: 1.8;
  color: var(--text-mute);
}

/* ---------- 章节 03 ---------- */
.page-about .about-team {
  display: grid;
  gap: clamp(24px, 3.4vw, 44px);
  margin-top: clamp(24px, 3vw, 38px);
}

@media (min-width: 940px) {
  .page-about .about-team {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, .9fr);
    align-items: start;
  }
}

.page-about .about-team__roles {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: var(--about-hairline);
}

.page-about .about-team__role {
  padding: clamp(14px, 1.8vw, 20px) 0;
  border-bottom: var(--about-hairline);
}

.page-about .about-team__role-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 6px;
}

.page-about .about-team__role-name {
  font-size: var(--step-0);
  font-weight: 600;
  color: var(--text);
}

.page-about .about-team__role-count {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: var(--step-1);
  color: var(--gold);
}

.page-about .about-team__role p {
  max-width: 38em;
  margin: 0;
  font-size: var(--step--1);
  line-height: 1.85;
  color: var(--text-mute);
}

.page-about .about-team__media {
  margin: 0;
}

/* ---------- 章节 04 ---------- */
.page-about .about-cadence {
  margin: clamp(24px, 3vw, 38px) 0 0;
  border-top: var(--about-hairline);
}

.page-about .about-cadence__row {
  display: grid;
  gap: 6px;
  padding: clamp(14px, 1.8vw, 20px) 0;
  border-bottom: var(--about-hairline);
}

@media (min-width: 700px) {
  .page-about .about-cadence__row {
    grid-template-columns: minmax(0, 220px) minmax(0, 1fr);
    gap: 28px;
    align-items: baseline;
  }
}

.page-about .about-cadence__key {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  letter-spacing: .04em;
  color: var(--gold);
}

.page-about .about-cadence__val {
  max-width: 40em;
  margin: 0;
  font-size: var(--step-0);
  line-height: 1.85;
  color: var(--text-dim);
}

/* ---------- 章节 05 ---------- */
.page-about .about-partners {
  display: grid;
  gap: 1px;
  margin-top: clamp(24px, 3vw, 38px);
  background: var(--line);
  border: var(--about-hairline);
}

@media (min-width: 800px) {
  .page-about .about-partners {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.page-about .about-partners__item {
  padding: clamp(18px, 2.4vw, 28px);
  background: var(--ink-800);
}

.page-about .about-partners__title {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-size: var(--step-1);
  font-weight: 700;
  color: var(--gold-light);
}

.page-about .about-partners__item p {
  margin: 0;
  font-size: var(--step--1);
  line-height: 1.85;
  color: var(--text-dim);
}

.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(24px, 3vw, 36px);
}

/* ---------- 尾部索引 ---------- */
.page-about .about-outro {
  border-top: var(--about-hairline);
  padding: clamp(40px, 6vw, 76px) 0 clamp(48px, 7vw, 92px);
}

.page-about .about-outro__inner {
  display: grid;
  gap: clamp(20px, 3vw, 44px);
}

@media (min-width: 900px) {
  .page-about .about-outro__inner {
    grid-template-columns: minmax(0, .8fr) minmax(0, 1.2fr);
  }
}

.page-about .about-outro__title {
  margin: 10px 0 0;
  font-family: var(--font-display);
  font-size: clamp(22px, 3vw, 32px);
  font-weight: 700;
  line-height: 1.35;
  color: var(--text);
}

.page-about .about-next {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: var(--about-hairline);
}

.page-about .about-next__link {
  position: relative;
  display: grid;
  gap: 4px;
  padding: clamp(14px, 1.8vw, 18px) 0;
  border-bottom: var(--about-hairline);
  text-decoration: none;
}

.page-about .about-next__link span:first-child {
  font-size: var(--step-0);
  color: var(--text);
  transition: color var(--dur) var(--ease);
}

.page-about .about-next__link span:last-child {
  font-size: var(--step--1);
  line-height: 1.75;
  color: var(--text-mute);
}

.page-about .about-next__link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 1px;
  background: var(--gold-light);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur) var(--ease);
}

.page-about .about-next__link:hover span:first-child {
  color: var(--gold-light);
}

.page-about .about-next__link:hover::after,
.page-about .about-next__link:focus-visible::after {
  transform: scaleX(1);
}

.page-about .about-next__link:focus-visible {
  outline: 2px solid var(--gold-light);
  outline-offset: 2px;
}

/* ---------- 窄屏收敛 ---------- */
@media (max-width: 640px) {
  .page-about .about-chapter__badge {
    position: static;
    margin-bottom: 14px;
    text-align: left;
  }

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

  .page-about .about-chapter__title {
    max-width: none;
  }

  .page-about .about-cover__title {
    max-width: none;
  }

  .page-about .about-timeline__year {
    font-size: var(--step-0);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-index-link,
  .page-about .about-index-link::after,
  .page-about .about-chapter__tag,
  .page-about .about-chapter__tip,
  .page-about .about-rail__item::before,
  .page-about .about-rail__year,
  .page-about .about-halls__item,
  .page-about .about-next__link span:first-child,
  .page-about .about-next__link::after {
    transition: none;
  }
}