.page-about {
  --about-num-size: clamp(56px, 13vw, 132px);
  --about-rail: 208px;
  padding-bottom: clamp(48px, 8vw, 96px);
}

/* ---------- 页面头部 ---------- */

.page-about .about-head {
  padding-top: clamp(22px, 4vw, 44px);
  padding-bottom: clamp(28px, 6vw, 60px);
}

.page-about .about-head__grid {
  display: grid;
  gap: clamp(28px, 5vw, 52px);
  margin-top: clamp(20px, 4vw, 34px);
}

.page-about .about-head__title {
  font-family: var(--font-display);
  font-weight: 300;
  font-size: clamp(34px, 6.6vw, 78px);
  line-height: 1.02;
  letter-spacing: -0.02em;
  color: var(--silver);
  margin: 16px 0 0;
}

.page-about .about-head__lead {
  font-size: clamp(15px, 1.6vw, 18px);
  line-height: 1.78;
  color: var(--silver-mid);
  margin: 18px 0 0;
  max-width: 40em;
}

.page-about .about-head__lede .btn {
  margin-top: 26px;
}

.page-about .about-head__facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--grid);
  border: 1px solid var(--grid);
  margin: 0;
}

.page-about .about-head__facts > div {
  background: var(--panel-deep);
  padding: 14px 16px 16px;
}

.page-about .about-head__facts dt {
  font-family: var(--font-index);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--silver-mid);
}

.page-about .about-head__facts dd {
  margin: 8px 0 0;
  font-family: var(--font-num);
  font-size: clamp(16px, 2.4vw, 21px);
  font-weight: 600;
  line-height: 1.2;
  color: var(--gold);
  font-variant-numeric: tabular-nums;
}

/* ---------- 金属强调字 ---------- */

.page-about .about-head__title b,
.page-about .chapter__title b {
  font-weight: 900;
  color: var(--gold-lt);
}

@supports ((-webkit-background-clip: text) or (background-clip: text)) {
  .page-about .about-head__title b,
  .page-about .chapter__title b {
    background-image: linear-gradient(102deg, var(--silver) 0%, var(--gold-lt) 38%, var(--gold) 64%, var(--silver) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    -webkit-text-fill-color: transparent;
  }
}

/* ---------- 主布局 ---------- */

.page-about .about-layout {
  display: grid;
  gap: clamp(30px, 6vw, 52px);
}

/* ---------- 章节目录 ---------- */

.page-about .about-toc {
  border-top: 1px solid var(--grid);
  padding-top: 16px;
}

.page-about .about-toc__list {
  list-style: none;
  margin: 12px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 4px 18px;
}

.page-about .about-toc__list a {
  display: block;
  padding: 8px 0;
  border-bottom: 1px solid var(--grid-soft);
  font-size: 14px;
  color: var(--silver-mid);
  text-decoration: none;
  transition: color 0.25s var(--ease), border-color 0.25s var(--ease);
}

.page-about .about-toc__list a span {
  font-family: var(--font-num);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--gold);
  margin-right: 8px;
}

.page-about .about-toc__list a:hover,
.page-about .about-toc__list a:focus-visible {
  color: var(--silver);
  border-color: var(--blue);
}

.page-about .about-toc__list a.is-active,
.page-about .about-toc__list a.is-in,
.page-about .about-toc__list a[aria-current="true"],
.page-about .about-toc__list a[aria-current="location"] {
  color: var(--silver);
  font-weight: 500;
  border-color: var(--gold);
}

.page-about .about-toc__list a.is-active span,
.page-about .about-toc__list a.is-in span,
.page-about .about-toc__list a[aria-current="true"] span,
.page-about .about-toc__list a[aria-current="location"] span {
  color: var(--gold-lt);
}

.page-about .about-toc__note {
  margin: 16px 0 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--silver-mid);
}

/* ---------- 章节 ---------- */

.page-about .chapter {
  border-top: 1px solid var(--grid);
  padding-top: clamp(20px, 3vw, 32px);
}

.page-about .chapter + .chapter {
  margin-top: clamp(46px, 8vw, 100px);
}

.page-about .chapter__head {
  display: grid;
  gap: 6px;
  margin-bottom: clamp(16px, 3vw, 28px);
}

.page-about .chapter__num {
  display: block;
  font-family: var(--font-num);
  font-size: var(--about-num-size);
  font-weight: 700;
  line-height: 0.82;
  letter-spacing: -0.04em;
  color: rgba(201, 166, 92, 0.18);
  -webkit-text-stroke: 1px rgba(201, 166, 92, 0.45);
  user-select: none;
}

.page-about .chapter__title {
  font-family: var(--font-display);
  font-weight: 300;
  font-size: clamp(24px, 3.3vw, 42px);
  line-height: 1.16;
  letter-spacing: -0.01em;
  color: var(--silver);
  margin: 0;
}

.page-about .chapter__body {
  max-width: 46em;
}

.page-about .chapter__body > p {
  font-size: 16px;
  line-height: 1.78;
  color: var(--silver);
  margin: 0 0 1.2em;
}

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

.page-about .chapter__body > p.lede {
  font-size: 18px;
  line-height: 1.72;
  color: var(--silver);
  margin-bottom: 1.1em;
}

/* ---------- 展览说明牌式数据标签 ---------- */

.page-about .spec-grid {
  display: grid;
  gap: 1px;
  background: var(--grid);
  border: 1px solid var(--grid);
  margin: 1.8em 0;
}

.page-about .spec {
  background: var(--panel-deep);
  padding: 16px 18px 18px;
  display: flex;
  flex-direction: column;
  gap: 7px;
}

.page-about .spec__k {
  font-family: var(--font-index);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--silver-mid);
}

.page-about .spec__v {
  font-family: var(--font-num);
  font-size: clamp(19px, 2.4vw, 24px);
  font-weight: 600;
  line-height: 1.2;
  color: var(--gold);
  font-variant-numeric: tabular-nums;
}

.page-about .spec__n {
  font-size: 13px;
  line-height: 1.65;
  color: var(--silver-mid);
}

/* ---------- 折叠注释 ---------- */

.page-about .fold {
  border: 1px solid var(--grid);
  background: var(--panel);
  margin: 1.8em 0 0;
}

.page-about .fold > summary {
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 13px 18px;
  font-size: 14px;
  color: var(--silver);
}

.page-about .fold > summary::-webkit-details-marker {
  display: none;
}

.page-about .fold > summary::after {
  content: "+";
  font-family: var(--font-num);
  font-size: 17px;
  line-height: 1;
  color: var(--gold);
}

.page-about .fold[open] > summary::after {
  content: "−";
}

.page-about .fold > summary:focus-visible {
  outline: 2px solid var(--pulse);
  outline-offset: -2px;
}

.page-about .fold__body {
  margin: 0;
  padding: 14px 18px 18px;
  border-top: 1px solid var(--grid-soft);
  font-size: 15px;
  line-height: 1.75;
  color: var(--silver-mid);
}

/* ---------- 栏目索引树 ---------- */

.page-about .tree {
  list-style: none;
  margin: 1.8em 0;
  padding: 0;
  border-top: 1px solid var(--grid);
}

.page-about .tree__branch {
  border-bottom: 1px solid var(--grid);
  padding: 16px 0 18px;
}

.page-about .tree__head {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 6px 12px;
}

.page-about .tree__idx {
  font-family: var(--font-num);
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--gold);
}

.page-about .tree__name {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 600;
  color: var(--silver);
  margin: 0;
}

.page-about .tree__count {
  margin-left: auto;
  font-family: var(--font-index);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--silver-mid);
  border: 1px solid var(--grid);
  padding: 2px 8px;
  white-space: nowrap;
}

.page-about .tree__leaves {
  list-style: none;
  margin: 12px 0 0 3px;
  padding: 0 0 0 14px;
  border-left: 1px solid var(--grid);
  display: flex;
  flex-wrap: wrap;
  gap: 6px 8px;
}

.page-about .tree__leaves li {
  font-size: 13px;
  line-height: 1.5;
  color: var(--silver-mid);
  background: var(--panel);
  border: 1px solid var(--grid-soft);
  padding: 4px 9px;
}

/* ---------- 三审流程 ---------- */

.page-about .review {
  list-style: none;
  margin: 1.8em 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--grid);
  border: 1px solid var(--grid);
}

.page-about .review__step {
  position: relative;
  background: var(--ink);
  padding: 22px 18px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.page-about .review__step::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--blue), rgba(31, 99, 216, 0));
}

.page-about .review__k {
  font-family: var(--font-index);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--gold);
}

.page-about .review__name {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 600;
  color: var(--silver);
  margin: 0;
}

.page-about .review__desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.72;
  color: var(--silver-mid);
}

/* ---------- 团队分工 ---------- */

.page-about .team {
  list-style: none;
  margin: 1.8em 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--grid);
  border: 1px solid var(--grid);
}

.page-about .team__item {
  background: var(--ink);
  padding: 20px 18px;
  display: flex;
  align-items: flex-start;
  gap: 16px;
}

.page-about .team__n {
  flex: none;
  width: 52px;
  font-family: var(--font-num);
  font-size: 30px;
  font-weight: 600;
  line-height: 1;
  color: var(--gold);
  font-variant-numeric: tabular-nums;
}

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

.page-about .team__name {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 600;
  color: var(--silver);
  margin: 0 0 7px;
}

.page-about .team__desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.72;
  color: var(--silver-mid);
}

/* ---------- 时间线 ---------- */

.page-about .timeline {
  list-style: none;
  margin: 1.8em 0;
  padding: 0;
}

.page-about .timeline__item {
  position: relative;
  padding: 0 0 34px 82px;
}

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

.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: 65px;
  top: 15px;
  bottom: 0;
  width: 1px;
  background: var(--grid);
}

.page-about .timeline__item:last-child::before {
  display: none;
}

.page-about .timeline__dot {
  position: absolute;
  left: 61px;
  top: 6px;
  width: 9px;
  height: 9px;
  background: var(--ink);
  border: 1px solid var(--gold);
  transform: rotate(45deg);
}

.page-about .timeline__item:focus-visible {
  outline: 2px solid var(--pulse);
  outline-offset: 6px;
}

.page-about .timeline__year {
  position: absolute;
  left: 0;
  top: 0;
  font-family: var(--font-num);
  font-size: 19px;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--gold);
  font-variant-numeric: tabular-nums;
}

.page-about .timeline__name {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 600;
  color: var(--silver);
  margin: 0 0 6px;
}

.page-about .timeline__desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.72;
  color: var(--silver-mid);
}

.page-about .timeline__kw {
  display: block;
  overflow: hidden;
  max-height: 0;
  opacity: 0;
  margin-top: 0;
  font-family: var(--font-index);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--pulse);
  transition: max-height 0.35s var(--ease), opacity 0.35s var(--ease), margin-top 0.35s var(--ease);
}

.page-about .timeline__item:hover .timeline__kw,
.page-about .timeline__item:focus .timeline__kw,
.page-about .timeline__item:focus-within .timeline__kw {
  max-height: 3em;
  opacity: 1;
  margin-top: 8px;
}

/* ---------- 相关页面 ---------- */

.page-about .about-next {
  margin-top: clamp(46px, 8vw, 88px);
  border-top: 1px solid var(--grid);
  padding-top: 20px;
}

.page-about .about-next__list {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--grid);
  border: 1px solid var(--grid);
}

.page-about .about-next__list li {
  background: var(--panel-deep);
}

.page-about .about-next__list a {
  display: block;
  padding: 16px 18px 4px;
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 600;
  color: var(--silver);
  text-decoration: none;
  transition: color 0.25s var(--ease);
}

.page-about .about-next__list a:hover {
  color: var(--pulse);
}

.page-about .about-next__list a:focus-visible {
  outline: 2px solid var(--pulse);
  outline-offset: -2px;
}

.page-about .about-next__list span {
  display: block;
  padding: 0 18px 16px;
  font-size: 13px;
  line-height: 1.62;
  color: var(--silver-mid);
}

/* ---------- 响应式 ---------- */

@media (max-width: 519px) {
  .page-about .about-toc__list {
    grid-template-columns: 1fr;
  }

  .page-about .team__item {
    flex-direction: column;
    gap: 10px;
  }

  .page-about .timeline__item {
    padding-left: 68px;
  }

  .page-about .timeline__item::before {
    left: 54px;
  }

  .page-about .timeline__dot {
    left: 50px;
  }
}

@media (min-width: 640px) {
  .page-about .spec-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 720px) {
  .page-about .chapter__head {
    grid-template-columns: auto minmax(0, 1fr);
    align-items: end;
    gap: 0 24px;
  }
}

@media (min-width: 860px) {
  .page-about .review {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-next__list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 960px) {
  .page-about .about-head__grid {
    grid-template-columns: minmax(0, 1.65fr) minmax(0, 1fr);
    align-items: end;
  }

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

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

@media (min-width: 1040px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: clamp(40px, 5vw, 72px);
    align-items: start;
  }

  .page-about .about-toc {
    position: sticky;
    top: 52px;
    border-top: none;
    border-left: 2px solid var(--grid);
    padding: 0 0 0 18px;
  }

  .page-about .about-toc__list {
    grid-template-columns: 1fr;
    gap: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-toc__list a,
  .page-about .timeline__kw,
  .page-about .about-next__list a {
    transition: none;
  }

  .page-about .timeline__kw {
    max-height: none;
    opacity: 1;
    margin-top: 8px;
  }
}
</style>