.page-about {
  --about-sec-gap: clamp(40px, 7vw, 76px);
  display: block;
  padding-bottom: clamp(56px, 9vw, 120px);
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumb {
  padding-top: clamp(16px, 3vw, 28px);
  font-size: 13px;
  color: var(--muted);
}
.page-about .about-crumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about .about-crumb li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--muted);
  opacity: .45;
}
.page-about .about-crumb a {
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color .25s var(--ease), border-color .25s var(--ease);
}
.page-about .about-crumb a:hover,
.page-about .about-crumb a:focus-visible {
  color: var(--cyan-soft);
  border-bottom-color: var(--hair);
}

/* ---------- 封面首屏 ---------- */
.page-about .about-cover {
  position: relative;
  padding-top: clamp(26px, 5vw, 52px);
  padding-bottom: clamp(28px, 5vw, 56px);
  border-bottom: 1px solid var(--hair);
  overflow: hidden;
}
.page-about .about-cover::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(43, 240, 198, .045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(43, 240, 198, .045) 1px, transparent 1px);
  background-size: 48px 48px;
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, .9), transparent 88%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, .9), transparent 88%);
  pointer-events: none;
}
.page-about .about-cover__grid {
  position: relative;
  display: grid;
  gap: clamp(28px, 5vw, 44px);
}
.page-about .about-cover h1 {
  margin: 12px 0 0;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(30px, 7vw, 56px);
  line-height: 1.14;
  letter-spacing: -0.01em;
  color: var(--text);
  max-width: 15em;
}
.page-about .about-cover .lead {
  margin-top: 18px;
  max-width: 34em;
}
.page-about .about-cover__index {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--hair);
  border: 1px solid var(--hair);
  border-radius: var(--r-sm);
  overflow: hidden;
}
.page-about .about-cover__index li {
  background: var(--panel);
  padding: 14px 16px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.page-about .about-cover__num {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}
.page-about .about-cover__index li:nth-child(4) .about-cover__num {
  color: var(--gold);
}
.page-about .about-cover__label {
  font-size: 12px;
  letter-spacing: .04em;
  color: var(--muted);
}

/* ---------- 主体两栏 ---------- */
.page-about .about-body {
  display: grid;
  gap: clamp(32px, 6vw, 56px);
  padding-top: clamp(32px, 6vw, 60px);
}

/* 侧栏目录 */
.page-about .about-toc {
  border: 1px solid var(--hair);
  border-radius: var(--r-sm);
  background: linear-gradient(160deg, rgba(14, 33, 28, .78), rgba(10, 27, 46, .55));
  padding: 16px 18px;
}
.page-about .about-toc__title {
  margin: 0 0 12px;
  font-family: var(--font-head);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .12em;
  color: var(--cyan-soft);
}
.page-about .about-toc__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2px;
}
.page-about .about-toc__list a {
  display: block;
  position: relative;
  padding: 8px 10px 8px 16px;
  font-size: 13.5px;
  line-height: 1.4;
  color: var(--muted);
  text-decoration: none;
  border-radius: 6px;
  transition: color .2s var(--ease), background-color .2s var(--ease);
}
.page-about .about-toc__list a::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 50%;
  width: 4px;
  height: 4px;
  margin-top: -2px;
  border-radius: 50%;
  background: var(--hair);
  transition: background-color .2s var(--ease), box-shadow .2s var(--ease);
}
.page-about .about-toc__list a:hover,
.page-about .about-toc__list a:focus-visible {
  color: var(--text);
  background: rgba(43, 240, 198, .07);
}
.page-about .about-toc__list a:hover::before,
.page-about .about-toc__list a:focus-visible::before {
  background: var(--cyan);
  box-shadow: 0 0 9px rgba(43, 240, 198, .75);
}

/* ---------- 章节 ---------- */
.page-about .about-sec {
  padding-top: var(--about-sec-gap);
  scroll-margin-top: 96px;
}
.page-about .about-sec:first-child {
  padding-top: 0;
}
.page-about .about-sec__head {
  position: relative;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  column-gap: 14px;
  row-gap: 8px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--hair);
  margin-bottom: clamp(20px, 4vw, 32px);
}
.page-about .about-sec__head::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 58px;
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), var(--gold));
}
.page-about .about-sec__no {
  grid-column: 1;
  grid-row: 1;
  align-self: center;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}
.page-about .about-sec__head h2 {
  grid-column: 2;
  grid-row: 1;
  margin: 0;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(22px, 4.4vw, 32px);
  line-height: 1.24;
  letter-spacing: -0.01em;
  color: var(--text);
}
.page-about .about-sec__intro {
  grid-column: 1 / -1;
  grid-row: 2;
  margin: 0;
  font-family: var(--font-serif);
  font-size: 15px;
  line-height: 1.85;
  color: var(--muted);
  max-width: 36em;
}

/* 正文段 */
.page-about .about-prose {
  max-width: 38em;
}
.page-about .about-prose p {
  margin: 0 0 1.15em;
  font-size: 15.5px;
  line-height: 1.85;
  color: var(--text);
}
.page-about .about-prose p:last-child {
  margin-bottom: 0;
}

/* 插图 */
.page-about .about-figure {
  margin: clamp(22px, 4vw, 34px) 0 0;
  padding: 0;
  border: 1px solid var(--hair);
  border-radius: var(--r-card);
  overflow: hidden;
  background: var(--panel);
}
.page-about .about-figure img {
  display: block;
  width: 100%;
  height: 100%;
  max-width: 100%;
  object-fit: cover;
}
.page-about .about-figure .media-frame__caption {
  padding: 10px 14px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--muted);
  border-top: 1px solid var(--hair);
}

/* 注释条 */
.page-about .about-note {
  margin: clamp(18px, 3vw, 26px) 0 0;
  padding-left: 14px;
  border-left: 2px solid var(--cyan);
  font-size: 13.5px;
  line-height: 1.85;
  color: var(--muted);
  max-width: 42em;
}
.page-about .about-note a {
  color: var(--cyan-soft);
  text-decoration: none;
  border-bottom: 1px solid rgba(141, 247, 223, .35);
  transition: color .2s var(--ease), border-color .2s var(--ease);
}
.page-about .about-note a:hover,
.page-about .about-note a:focus-visible {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

/* ---------- 五道工序 ---------- */
.page-about .flow {
  list-style: none;
  margin: clamp(24px, 4vw, 36px) 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}
.page-about .flow__step {
  position: relative;
  padding: 18px 16px 20px;
  background: var(--card-bg);
  border: 1px solid var(--hair);
  border-top: 2px solid var(--cyan);
  border-radius: var(--r-sm);
  box-shadow: var(--shadow-card);
  transition: transform .25s var(--ease), border-color .25s var(--ease);
}
.page-about .flow__step:nth-child(3),
.page-about .flow__step:nth-child(4) {
  border-top-color: var(--cyan-soft);
}
.page-about .flow__step:nth-child(5) {
  border-top-color: var(--gold);
}
.page-about .flow__step:hover {
  transform: translateY(-2px);
  border-color: rgba(43, 240, 198, .38);
}
.page-about .flow__no {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--gold);
  font-variant-numeric: tabular-nums;
}
.page-about .flow__title {
  margin: 8px 0 8px;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 16px;
  line-height: 1.3;
  color: var(--text);
}
.page-about .flow__step p {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.8;
  color: var(--muted);
}

/* ---------- 四个小组 ---------- */
.page-about .teams {
  display: grid;
  gap: 10px;
}
.page-about .team {
  border: 1px solid var(--hair);
  border-radius: var(--r-sm);
  background: rgba(14, 33, 28, .55);
  overflow: hidden;
  transition: border-color .25s var(--ease);
}
.page-about .team[open] {
  border-color: rgba(43, 240, 198, .42);
}
.page-about .team summary {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 14px;
  padding: 15px 16px;
  cursor: pointer;
  list-style: none;
  transition: background-color .2s var(--ease);
}
.page-about .team summary::-webkit-details-marker {
  display: none;
}
.page-about .team summary:hover {
  background: rgba(43, 240, 198, .05);
}
.page-about .team summary:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: -2px;
}
.page-about .team__no {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}
.page-about .team__label {
  display: flex;
  flex-direction: column;
  gap: 3px;
  min-width: 0;
}
.page-about .team__name {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 17px;
  line-height: 1.3;
  color: var(--text);
}
.page-about .team__role {
  font-size: 12.5px;
  line-height: 1.4;
  color: var(--muted);
}
.page-about .team__mark {
  position: relative;
  flex: none;
  width: 18px;
  height: 18px;
}
.page-about .team__mark::before,
.page-about .team__mark::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  background: var(--cyan);
  transition: transform .25s var(--ease), opacity .25s var(--ease);
}
.page-about .team__mark::before {
  width: 14px;
  height: 1.5px;
  margin: -0.75px 0 0 -7px;
}
.page-about .team__mark::after {
  width: 1.5px;
  height: 14px;
  margin: -7px 0 0 -0.75px;
}
.page-about .team[open] .team__mark::after {
  transform: scaleY(0);
  opacity: 0;
}
.page-about .team__body {
  padding: 15px 16px 18px 16px;
  border-top: 1px solid var(--hair);
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--muted);
}
.page-about .team__body p {
  margin: 0;
}
.page-about .team__body ul {
  list-style: none;
  margin: 12px 0 0;
  padding: 0;
  display: grid;
  gap: 7px;
}
.page-about .team__body li {
  position: relative;
  padding-left: 16px;
}
.page-about .team__body li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .78em;
  width: 7px;
  height: 1px;
  background: var(--cyan);
}

/* ---------- 常设专题 ---------- */
.page-about .topics {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}
.page-about .topic {
  display: flex;
  flex-direction: column;
  gap: 9px;
  padding: 18px;
  border: 1px solid var(--hair);
  border-radius: var(--r-sm);
  background: linear-gradient(158deg, rgba(14, 33, 28, .86), rgba(10, 27, 46, .6));
  transition: transform .25s var(--ease), border-color .25s var(--ease);
}
.page-about .topic:hover {
  transform: translateY(-2px);
  border-color: rgba(43, 240, 198, .4);
}
.page-about .topic .tag {
  align-self: flex-start;
}
.page-about .topic h3 {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 18px;
  line-height: 1.3;
  color: var(--text);
}
.page-about .topic p {
  margin: 0;
  font-size: 14px;
  line-height: 1.82;
  color: var(--muted);
}
.page-about .topic__cadence {
  margin-top: auto;
  padding-top: 8px;
  font-size: 12px;
  letter-spacing: .05em;
  color: var(--cyan-soft);
}

/* ---------- 时间轴 ---------- */
.page-about .timeline {
  position: relative;
  margin-top: clamp(22px, 4vw, 34px);
}
.page-about .timeline__texture {
  position: absolute;
  right: -6%;
  top: -4%;
  width: min(400px, 58%);
  height: auto;
  max-width: 100%;
  object-fit: cover;
  opacity: .13;
  border-radius: var(--r-card);
  mix-blend-mode: screen;
  pointer-events: none;
}
.page-about .tl {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about .tl::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 10px;
  width: 1px;
  background: linear-gradient(180deg, var(--cyan), rgba(43, 240, 198, .22) 55%, var(--gold-deep));
}
.page-about .tl__node {
  position: relative;
  padding: 0 0 28px 30px;
}
.page-about .tl__node:last-child {
  padding-bottom: 0;
}
.page-about .tl__node::before {
  content: "";
  position: absolute;
  left: 0;
  top: 7px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--ink);
  border: 1.5px solid var(--cyan);
  box-shadow: 0 0 0 4px rgba(43, 240, 198, .08);
  transition: background-color .25s var(--ease), box-shadow .25s var(--ease);
}
.page-about .tl__node:hover::before,
.page-about .tl__node:focus-within::before {
  background: var(--cyan);
  box-shadow: 0 0 0 6px rgba(43, 240, 198, .18);
}
.page-about .tl__year {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .07em;
  color: var(--gold);
  font-variant-numeric: tabular-nums;
}
.page-about .tl__card {
  padding: 16px 18px;
  border: 1px solid var(--hair);
  border-radius: var(--r-sm);
  background: rgba(14, 33, 28, .6);
  transition: border-color .25s var(--ease), background-color .25s var(--ease);
}
.page-about .tl__card:hover,
.page-about .tl__card:focus-visible {
  border-color: rgba(43, 240, 198, .45);
  background: rgba(14, 33, 28, .82);
  outline: none;
}
.page-about .tl__title {
  margin: 0 0 8px;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 17px;
  line-height: 1.3;
  color: var(--text);
}
.page-about .tl__desc {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--muted);
}
.page-about .tl__more {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.8;
  color: var(--cyan-soft);
}

/* ---------- 覆盖与用户 ---------- */
.page-about .reach {
  list-style: none;
  margin: 0 0 clamp(20px, 4vw, 30px);
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--hair);
  border: 1px solid var(--hair);
  border-radius: var(--r-card);
  overflow: hidden;
}
.page-about .reach__item {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 18px 16px 20px;
  background: linear-gradient(150deg, rgba(14, 33, 28, .94), rgba(5, 16, 13, .94));
}
.page-about .reach__figure {
  display: flex;
  align-items: baseline;
  gap: 6px;
}
.page-about .reach__num {
  display: inline-block;
  padding: 0 3px;
  font-family: var(--font-mono);
  font-size: clamp(26px, 6.4vw, 38px);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--gold);
  font-variant-numeric: tabular-nums;
  background: linear-gradient(180deg, transparent 62%, rgba(240, 195, 106, .22) 62%);
}
.page-about .reach__unit {
  font-size: 12.5px;
  color: var(--muted);
}
.page-about .reach__desc {
  margin: 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
}

/* ---------- 合作 CTA ---------- */
.page-about .about-cta {
  display: grid;
  gap: 18px;
  padding: clamp(20px, 4vw, 32px);
  border: 1px solid var(--hair);
  border-radius: var(--r-card);
  background-image:
    radial-gradient(120% 90% at 100% 0%, rgba(43, 240, 198, .14), transparent 62%),
    linear-gradient(150deg, rgba(10, 27, 46, .9), rgba(5, 16, 13, .92));
}
.page-about .about-cta__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.9;
  color: var(--text);
  max-width: 40em;
}
.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

/* ---------- 窄屏修正 ---------- */
@media (max-width: 480px) {
  .page-about .about-cover__index {
    grid-template-columns: 1fr;
  }
  .page-about .about-toc__list {
    grid-template-columns: 1fr;
  }
  .page-about .reach {
    grid-template-columns: 1fr;
  }
  .page-about .about-cta__actions .btn {
    width: 100%;
    justify-content: center;
  }
}

/* ---------- 平板竖屏起 ---------- */
@media (min-width: 700px) {
  .page-about .topics {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .reach {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .about-prose p {
    font-size: 16px;
  }
}

/* ---------- 桌面 ---------- */
@media (min-width: 900px) {
  .page-about .about-cover__grid {
    grid-template-columns: minmax(0, 7.2fr) minmax(0, 4fr);
    column-gap: clamp(36px, 6vw, 84px);
    align-items: end;
  }
  .page-about .about-cover__index {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .flow {
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 10px;
    align-items: start;
  }
  .page-about .flow__step:nth-child(1) { margin-top: 0; }
  .page-about .flow__step:nth-child(2) { margin-top: 22px; }
  .page-about .flow__step:nth-child(3) { margin-top: 44px; }
  .page-about .flow__step:nth-child(4) { margin-top: 66px; }
  .page-about .flow__step:nth-child(5) { margin-top: 88px; }
  .page-about .flow__step p {
    font-size: 13px;
  }
}

@media (min-width: 1024px) {
  .page-about .about-body {
    grid-template-columns: minmax(0, 1fr) 246px;
    grid-template-areas: "main toc";
    align-items: start;
    column-gap: clamp(36px, 5vw, 72px);
  }
  .page-about .about-stream {
    grid-area: main;
  }
  .page-about .about-toc {
    grid-area: toc;
    position: sticky;
    top: 92px;
  }
  .page-about .about-toc__list {
    grid-template-columns: 1fr;
  }
  .page-about .tl__more {
    margin-top: 10px;
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height .35s var(--ease), opacity .3s var(--ease), margin-top .3s var(--ease);
  }
  .page-about .tl__node:hover .tl__more,
  .page-about .tl__node:focus-within .tl__more {
    max-height: 180px;
    opacity: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .flow__step,
  .page-about .topic,
  .page-about .tl__card,
  .page-about .team__mark::before,
  .page-about .team__mark::after {
    transition: none;
  }
  .page-about .flow__step:hover,
  .page-about .topic:hover {
    transform: none;
  }
  .page-about .tl__more {
    max-height: none;
    opacity: 1;
    transition: none;
  }
}