.page-about {
  counter-reset: about-sec;
  background: var(--cream);
  color: var(--ink);
  font-family: var(--font-body);
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  padding-block: clamp(24px, 4vw, 48px) clamp(44px, 6vw, 84px);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  z-index: -1;
  top: -8%;
  right: -16%;
  width: min(80vw, 640px);
  aspect-ratio: 1 / 1;
  background: linear-gradient(155deg, var(--red) 0%, var(--red-deep) 100%);
  clip-path: polygon(24% 0, 100% 0, 100% 76%, 0 100%);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  z-index: -1;
  left: -14%;
  bottom: -22%;
  width: min(48vw, 340px);
  aspect-ratio: 1 / 1;
  border: 1px solid var(--gold);
  transform: rotate(12deg);
  opacity: 0.45;
}

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

.page-about .breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin: 0 0 clamp(18px, 3vw, 30px);
  padding: 0;
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--ink-2);
}

.page-about .breadcrumb li + li::before {
  content: "／";
  margin-right: 8px;
  color: var(--line);
}

.page-about .breadcrumb a {
  color: var(--celadon);
  text-decoration: none;
}

.page-about .breadcrumb a:hover {
  color: var(--red);
}

.page-about .about-hero .eyebrow {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--red);
  text-transform: uppercase;
}

.page-about .about-hero__title {
  margin: 0 0 clamp(18px, 2.4vw, 28px);
  max-width: 17ch;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(34px, 6.2vw, 80px);
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.page-about .about-hero__mark {
  display: inline-block;
  color: var(--red);
  background-image: linear-gradient(var(--gold-soft), var(--gold-soft));
  background-repeat: no-repeat;
  background-position: 0 92%;
  background-size: 100% 0.22em;
}

.page-about .about-hero__lead {
  max-width: 60ch;
  margin: 0 0 clamp(24px, 3.4vw, 40px);
  font-size: clamp(15.5px, 1.5vw, 18px);
  line-height: 1.85;
  color: var(--ink-2);
}

.page-about .about-hero__stats {
  display: flex;
  flex-wrap: wrap;
  gap: clamp(18px, 3.4vw, 52px);
  margin: 0 0 clamp(26px, 3.6vw, 44px);
  padding-top: clamp(16px, 2vw, 24px);
  border-top: 1px solid rgba(140, 131, 119, 0.45);
}

.page-about .about-hero__stats .stat {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.page-about .about-hero__stats .stat__value {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(20px, 2.4vw, 30px);
  font-weight: 700;
  line-height: 1.1;
  color: var(--red);
}

.page-about .about-hero__stats .stat__label {
  font-size: 11.5px;
  letter-spacing: 0.2em;
  color: var(--ink-2);
}

/* ---------- 图片框 ---------- */
.page-about .img-frame {
  margin: clamp(24px, 3.4vw, 40px) 0 0;
  padding: 9px;
  background: var(--paper);
  border: 1px solid rgba(201, 162, 39, 0.55);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 18px), calc(100% - 18px) 100%, 0 100%);
}

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

.page-about .img-frame__caption {
  margin: 10px 2px 2px;
  font-size: 12px;
  line-height: 1.7;
  letter-spacing: 0.06em;
  color: var(--line);
}

.page-about .about-hero__figure {
  margin-top: 0;
}

/* ---------- 左签右表骨架 ---------- */
.page-about .about-body {
  padding-block: clamp(38px, 5.5vw, 84px);
}

.page-about .split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(22px, 4vw, 58px);
}

.page-about .split__rail,
.page-about .split__main {
  min-width: 0;
}

.page-about .fo-toc .eyebrow {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.22em;
  color: var(--line);
}

.page-about .fo-toc__list {
  display: flex;
  gap: 4px;
  margin: 0;
  padding: 0 0 6px;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .fo-toc__link {
  display: block;
  padding: 9px 12px;
  white-space: nowrap;
  font-size: 12.5px;
  letter-spacing: 0.12em;
  color: var(--ink-2);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  transition: color 160ms ease, border-color 160ms ease, background-color 160ms ease;
}

.page-about .fo-toc__link:hover,
.page-about .fo-toc__link[aria-current] {
  color: var(--red);
  border-bottom-color: var(--gold);
  background: rgba(201, 162, 39, 0.09);
}

@media (min-width: 960px) {
  .page-about .split {
    grid-template-columns: 186px minmax(0, 1fr);
    gap: clamp(36px, 5vw, 76px);
  }

  .page-about .split__rail {
    position: sticky;
    top: 104px;
    align-self: start;
  }

  .page-about .fo-toc__list {
    display: block;
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .fo-toc__link {
    white-space: normal;
    line-height: 1.5;
    border-bottom: 0;
    border-left: 2px solid transparent;
  }

  .page-about .fo-toc__link:hover,
  .page-about .fo-toc__link[aria-current] {
    border-left-color: var(--gold);
    border-bottom-color: transparent;
  }
}

/* ---------- 章节 ---------- */
.page-about .about-section {
  counter-increment: about-sec;
  padding-block: clamp(30px, 4vw, 54px);
  border-top: 1px solid rgba(140, 131, 119, 0.32);
}

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

.page-about .about-section__no {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin: 0 0 14px;
  font-size: 11.5px;
  letter-spacing: 0.22em;
  color: var(--line);
}

.page-about .about-section__no-num::before {
  content: counter(about-sec, decimal-leading-zero);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--red);
}

.page-about .about-section__title {
  margin: 0 0 clamp(16px, 2vw, 22px);
  max-width: 24ch;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(23px, 3.2vw, 38px);
  line-height: 1.24;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.page-about .prose p {
  max-width: 68ch;
  margin: 0 0 1.05em;
  font-size: clamp(15.5px, 1.25vw, 17px);
  line-height: 1.85;
  color: var(--ink-2);
}

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

.page-about .prose strong {
  font-weight: 600;
  color: var(--ink);
}

.page-about .prose a {
  color: var(--red);
  text-decoration: none;
  border-bottom: 1px solid var(--gold);
}

.page-about .prose a:hover {
  color: var(--red-deep);
}

/* ---------- 时间线 ---------- */
.page-about .timeline {
  margin-top: clamp(20px, 2.6vw, 30px);
}

.page-about .timeline__track {
  display: flex;
  gap: 16px;
  padding-bottom: 22px;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
}

.page-about .tl-node {
  position: relative;
  flex: 0 0 min(264px, 74vw);
  scroll-snap-align: start;
  padding: 24px 18px 22px;
  background: var(--paper);
  border-top: 3px solid var(--gold);
  box-shadow: 0 1px 0 rgba(140, 131, 119, 0.35);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 16px), calc(100% - 16px) 100%, 0 100%);
}

.page-about .tl-node::before {
  content: "";
  position: absolute;
  top: -9px;
  left: 20px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--gold);
  box-shadow: 0 0 0 4px var(--cream);
}

.page-about .tl-node__year {
  display: block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 25px;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--red);
}

.page-about .tl-node__text {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--ink-2);
}

/* ---------- 团队矩阵 ---------- */
.page-about .team-matrix {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin: clamp(22px, 2.8vw, 32px) 0 0;
}

.page-about .team-cell {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 20px 16px 22px;
  background: var(--ink);
  color: var(--cream);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);
}

.page-about .team-cell__no {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(26px, 3.4vw, 34px);
  font-weight: 700;
  line-height: 1;
  color: var(--gold);
}

.page-about .team-cell__name {
  font-size: 13.5px;
  letter-spacing: 0.14em;
  color: var(--cream);
}

.page-about .team-cell__unit {
  font-size: 11.5px;
  letter-spacing: 0.2em;
  color: rgba(246, 239, 226, 0.55);
}

@media (min-width: 720px) {
  .page-about .team-matrix {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 14px;
  }
}

/* ---------- 折叠 ---------- */
.page-about .fold {
  border-top: 1px solid rgba(140, 131, 119, 0.32);
}

.page-about .fold:last-of-type {
  border-bottom: 1px solid rgba(140, 131, 119, 0.32);
}

.page-about .fold__summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 15px 2px;
  cursor: pointer;
  list-style: none;
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--ink);
}

.page-about .fold__summary::-webkit-details-marker {
  display: none;
}

.page-about .fold__summary::after {
  content: "＋";
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--gold);
}

.page-about .fold[open] .fold__summary::after {
  content: "－";
}

.page-about .fold__summary:hover {
  color: var(--red);
}

.page-about .fold__body {
  padding: 0 2px 20px;
}

.page-about .fold__body ul {
  margin: 0;
  padding-left: 18px;
}

.page-about .fold__body li {
  margin-bottom: 6px;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--ink-2);
}

.page-about .fold__body li:last-child {
  margin-bottom: 0;
}

/* ---------- 版本列表 ---------- */
.page-about .ver-list {
  margin: clamp(20px, 2.6vw, 30px) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .ver-item {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 10px;
  padding: clamp(16px, 2vw, 22px) 0;
  border-bottom: 1px dashed rgba(140, 131, 119, 0.5);
}

.page-about .ver-item:first-child {
  border-top: 1px dashed rgba(140, 131, 119, 0.5);
}

.page-about .ver-tag {
  justify-self: start;
  align-self: start;
  display: inline-block;
  padding: 4px 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  background: var(--red);
  color: var(--paper);
  clip-path: polygon(0 0, 100% 0, calc(100% - 8px) 100%, 0 100%);
}

.page-about .ver-tag--ghost {
  background: rgba(79, 133, 119, 0.14);
  color: var(--celadon);
}

.page-about .ver-item__body p {
  margin: 0;
  max-width: 62ch;
  font-size: 15px;
  line-height: 1.82;
  color: var(--ink-2);
}

@media (min-width: 720px) {
  .page-about .ver-item {
    grid-template-columns: 128px minmax(0, 1fr);
    gap: 22px;
    align-items: baseline;
  }
}

/* ---------- 行动区 ---------- */
.page-about .about-cta {
  position: relative;
  overflow: hidden;
  margin-top: clamp(44px, 6vw, 84px);
  padding: clamp(28px, 4.4vw, 58px);
  background: var(--ink-2);
  color: var(--cream);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 26px), calc(100% - 26px) 100%, 0 100%);
}

.page-about .about-cta::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: clamp(82px, 14vw, 180px);
  height: 3px;
  background: linear-gradient(90deg, var(--red) 0%, var(--gold) 100%);
}

.page-about .about-cta__title {
  position: relative;
  margin: 0 0 16px;
  max-width: 22ch;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(22px, 3vw, 36px);
  line-height: 1.26;
  letter-spacing: -0.01em;
  color: var(--cream);
}

.page-about .about-cta__text {
  position: relative;
  max-width: 64ch;
  margin: 0 0 clamp(22px, 3vw, 32px);
  font-size: clamp(14.5px, 1.2vw, 16.5px);
  line-height: 1.85;
  color: rgba(246, 239, 226, 0.78);
}

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

.page-about .about-cta__actions .btn {
  text-decoration: none;
}

.page-about .about-cta__actions .btn--ghost {
  color: var(--cream);
  border: 1px solid rgba(246, 239, 226, 0.45);
}

.page-about .about-cta__actions .btn--ghost:hover {
  color: var(--ink);
  background: var(--cream);
  border-color: var(--cream);
}

/* ---------- 焦点可见性 ---------- */
.page-about a:focus-visible,
.page-about summary:focus-visible {
  outline: 2px solid var(--gold);
  outline-offset: 3px;
}

/* ---------- 窄屏收紧 ---------- */
@media (max-width: 560px) {
  .page-about .about-hero::before {
    width: 92vw;
    top: -14%;
    right: -30%;
    opacity: 0.9;
  }

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

  .page-about .timeline__track {
    gap: 12px;
  }

  .page-about .tl-node {
    flex: 0 0 80vw;
  }

  .page-about .about-cta__actions .btn {
    width: 100%;
    text-align: center;
  }
}

/* ---------- 无障碍降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  .page-about .fo-toc__link,
  .page-about .tl-node {
    transition: none;
  }

  .page-about .timeline__track {
    scroll-behavior: auto;
  }
}