.page-about {
  background: var(--paper);
  color: var(--graphite);
  font-family: var(--ff-sans);
  overflow-x: hidden;
}

/* ---------- 顶部横幅 ---------- */
.page-about .about-banner {
  position: relative;
  background: var(--ink);
}
.page-about .about-banner__img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: clamp(150px, 26vw, 420px);
  object-fit: cover;
}
.page-about .about-banner__rule {
  height: 6px;
  background: var(--flag);
}

/* ---------- 面包屑 ---------- */
.page-about .breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  padding: 22px 0 0;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--graphite);
}
.page-about .breadcrumb a {
  color: var(--graphite);
  text-decoration: none;
  border-bottom: 1px solid var(--grid);
}
.page-about .breadcrumb a:hover,
.page-about .breadcrumb a:focus-visible {
  color: var(--ink);
  border-bottom-color: var(--vermilion);
}
.page-about .breadcrumb span[aria-current="page"] {
  color: var(--ink);
  font-weight: 600;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding: clamp(26px, 5vw, 60px) 0 clamp(34px, 5vw, 68px);
  border-bottom: 1px solid var(--grid);
}
.page-about .about-hero__kicker {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 0 0 20px;
  font-family: var(--ff-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--vermilion);
}
.page-about .about-hero__kicker::before {
  content: "";
  width: 36px;
  height: 1px;
  background: var(--vermilion);
  flex: 0 0 auto;
}
.page-about .about-hero h1 {
  margin: 0 0 24px;
  max-width: 15em;
  font-size: clamp(32px, 7vw, 84px);
  line-height: 1.04;
  letter-spacing: 0.045em;
  font-weight: 900;
  color: var(--ink);
}
.page-about .about-hero__lede {
  margin: 0 0 36px;
  max-width: 36em;
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.85;
  color: var(--graphite);
}

.page-about .about-stats {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--grid);
  border: 1px solid var(--grid);
}
.page-about .about-stats > li {
  display: flex;
  flex-direction: column;
  gap: 8px;
  min-width: 0;
  padding: 18px 16px;
  background: var(--white);
}
.page-about .about-stats__num {
  font-size: clamp(24px, 3.6vw, 36px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--ink);
}
.page-about .about-stats__label {
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--graphite);
}

/* ---------- 主体两栏 ---------- */
.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 32px;
  padding-top: 40px;
  padding-bottom: 72px;
}

/* ---------- 章节索引 ---------- */
.page-about .about-index__title {
  margin: 0 0 10px;
  font-family: var(--ff-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--graphite);
}
.page-about .about-index .toc {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding: 2px 2px 10px;
  scrollbar-width: thin;
}
.page-about .about-index .toc a {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-height: 44px;
  padding: 0 14px;
  border: 1px solid var(--grid);
  background: var(--white);
  color: var(--graphite);
  font-size: 13px;
  letter-spacing: 0.04em;
  text-decoration: none;
  white-space: nowrap;
}
.page-about .about-index .toc a .mono {
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--blue);
}
.page-about .about-index .toc a:hover {
  border-color: var(--ink);
  color: var(--ink);
}
.page-about .about-index .toc a:focus-visible {
  outline: 2px solid var(--vermilion);
  outline-offset: 2px;
}
.page-about .about-index .toc a[aria-current="true"] {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--white);
}
.page-about .about-index .toc a[aria-current="true"] .mono {
  color: var(--sky);
}

/* ---------- 内容流 ---------- */
.page-about .about-flow {
  display: flex;
  flex-direction: column;
  gap: clamp(46px, 7vw, 92px);
  min-width: 0;
}
.page-about .about-section {
  min-width: 0;
  scroll-margin-top: 20px;
}
.page-about .about-section__head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding-bottom: 12px;
  margin-bottom: 24px;
  border-bottom: 1px solid var(--ink);
}
.page-about .about-section__no {
  flex: 0 0 auto;
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--vermilion);
}
.page-about .about-section__head h2 {
  margin: 0;
  font-size: clamp(23px, 3.4vw, 38px);
  line-height: 1.16;
  letter-spacing: 0.05em;
  font-weight: 800;
  color: var(--ink);
}
.page-about .about-section p {
  margin: 0 0 16px;
  max-width: 40em;
  font-size: 15px;
  line-height: 1.85;
}
.page-about .about-section p:last-child {
  margin-bottom: 0;
}

/* ---------- 起点 ---------- */
.page-about .about-origin {
  display: grid;
  gap: 24px;
  margin-top: 20px;
}
.page-about .about-origin__text {
  min-width: 0;
}
.page-about .about-origin__note {
  align-self: start;
  padding: 22px 20px;
  background: var(--ink);
  color: var(--white);
}
.page-about .about-origin__note .mono {
  display: block;
  margin: 0 0 10px;
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--sky);
}
.page-about .about-origin__note p:last-child {
  margin: 0;
  max-width: none;
  font-size: 14px;
  line-height: 1.8;
  color: var(--white);
}

/* ---------- 版本时间轴 ---------- */
.page-about .about-timeline {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
}
.page-about .about-timeline__item {
  position: relative;
  padding-left: 28px;
  padding-bottom: 6px;
}
.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 22px;
  bottom: -6px;
  width: 1px;
  background: var(--grid);
}
.page-about .about-timeline__item:last-child::before {
  display: none;
}
.page-about .about-node {
  border-bottom: 1px solid var(--grid);
}
.page-about .about-node__summary {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px;
  min-height: 44px;
  padding: 13px 32px 13px 0;
  cursor: pointer;
  list-style: none;
}
.page-about .about-node__summary::-webkit-details-marker {
  display: none;
}
.page-about .about-node__summary::before {
  content: "";
  position: absolute;
  left: -28px;
  top: 19px;
  width: 9px;
  height: 9px;
  box-sizing: content-box;
  border: 2px solid var(--grid);
  border-radius: 50%;
  background: var(--paper);
}
.page-about .about-node__summary::after {
  content: "+";
  position: absolute;
  right: 0;
  top: 12px;
  font-family: var(--ff-mono);
  font-size: 18px;
  line-height: 1;
  color: var(--blue);
}
.page-about .about-node[open] > .about-node__summary::after {
  content: "\2013";
}
.page-about .about-node__summary:focus-visible {
  outline: 2px solid var(--vermilion);
  outline-offset: 3px;
}
.page-about .about-node__year {
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--blue);
  font-weight: 600;
}
.page-about .about-node__title {
  font-size: clamp(16px, 2vw, 18px);
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--ink);
}
.page-about .about-node__body p {
  margin: 0 0 10px;
  max-width: 40em;
  font-size: 14.5px;
  line-height: 1.85;
}
.page-about .about-node__body {
  padding-bottom: 16px;
}
.page-about .about-node__body p:last-child {
  margin-bottom: 0;
}
.page-about .about-timeline__item--current .about-node__summary::before {
  border-color: var(--turquoise);
  background: var(--turquoise);
}
.page-about .about-timeline__item--current .about-node__year {
  color: var(--turquoise);
}

/* ---------- 图片容器 ---------- */
.page-about .about-figure {
  margin: 30px 0 0;
  border: 1px solid var(--grid);
  background: var(--white);
}
.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
}
.page-about .about-figure--tall {
  max-width: 520px;
}
.page-about .about-figure figcaption {
  padding: 13px 16px;
  border-top: 1px solid var(--grid);
  font-size: 12px;
  line-height: 1.7;
  color: var(--graphite);
}

/* ---------- 维护者 ---------- */
.page-about .about-team {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--grid);
  border: 1px solid var(--grid);
}
.page-about .about-team__cell {
  --cell-accent: var(--blue);
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 8px;
  min-width: 0;
  padding: 20px 18px 20px 22px;
  background: var(--white);
}
.page-about .about-team__cell::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 4px;
  height: 100%;
  background: var(--cell-accent);
  transition: width 0.18s ease;
}
.page-about .about-team__cell:nth-child(2) {
  --cell-accent: var(--turquoise);
}
.page-about .about-team__cell:nth-child(3) {
  --cell-accent: var(--saffron);
}
.page-about .about-team__cell:nth-child(4) {
  --cell-accent: var(--vermilion);
}
.page-about .about-team__cell:hover::before,
.page-about .about-team__cell:focus-within::before {
  width: 8px;
}
.page-about .about-team__num {
  font-size: 30px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--ink);
}
.page-about .about-team__role {
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--ink);
}
.page-about .about-team__desc {
  font-size: 13px;
  line-height: 1.75;
  color: var(--graphite);
}

/* ---------- 服务半径 ---------- */
.page-about .about-radius {
  display: grid;
  gap: 26px;
  margin-top: 20px;
}
.page-about .about-radius__text {
  min-width: 0;
}
.page-about .about-radius__fig {
  margin: 0;
}

/* ---------- 响应机制 ---------- */
.page-about .about-flowline {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
}
.page-about .about-flowline > li {
  padding: 20px 18px;
  background: var(--white);
  border: 1px solid var(--grid);
  border-top: 3px solid var(--blue);
}
.page-about .about-flowline > li:nth-child(2) {
  border-top-color: var(--turquoise);
}
.page-about .about-flowline > li:nth-child(3) {
  border-top-color: var(--saffron);
}
.page-about .about-flowline > li:nth-child(4) {
  border-top-color: var(--vermilion);
}
.page-about .about-flowline__no {
  display: block;
  margin-bottom: 8px;
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--vermilion);
}
.page-about .about-flowline h3 {
  margin: 0 0 8px;
  font-size: 17px;
  letter-spacing: 0.05em;
  color: var(--ink);
}
.page-about .about-flowline p {
  margin: 0;
  max-width: 34em;
  font-size: 14px;
  line-height: 1.8;
}
.page-about .about-escalate {
  margin-top: 24px;
  padding: 16px 18px;
  border-left: 4px solid var(--saffron);
  background: var(--white);
  font-size: 14px;
  line-height: 1.8;
  color: var(--ink);
}

/* ---------- 后续入口 ---------- */
.page-about .about-next {
  padding-top: 28px;
  border-top: 1px solid var(--ink);
}
.page-about .about-next h2 {
  margin: 0 0 20px;
  font-size: clamp(20px, 2.6vw, 26px);
  letter-spacing: 0.06em;
  font-weight: 800;
  color: var(--ink);
}
.page-about .about-next__links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--grid);
  border: 1px solid var(--grid);
}
.page-about .about-next__links a {
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-height: 44px;
  padding: 18px;
  background: var(--white);
  color: var(--graphite);
  text-decoration: none;
  transition: background 0.18s ease;
}
.page-about .about-next__links a:hover,
.page-about .about-next__links a:focus-visible {
  background: var(--paper);
}
.page-about .about-next__links a:focus-visible {
  outline: 2px solid var(--vermilion);
  outline-offset: -2px;
}
.page-about .about-next__label {
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--ink);
}
.page-about .about-next__desc {
  font-size: 13px;
  line-height: 1.7;
}

/* ---------- 断点 ---------- */
@media (min-width: 720px) {
  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .about-team {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .about-flowline {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .about-next__links {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 860px) {
  .page-about .about-origin {
    grid-template-columns: minmax(0, 1fr) minmax(0, 300px);
    gap: 40px;
  }
  .page-about .about-radius {
    grid-template-columns: minmax(0, 1fr) minmax(0, 360px);
    gap: 40px;
    align-items: start;
  }
}

@media (min-width: 960px) {
  .page-about .about-body {
    grid-template-columns: 200px minmax(0, 1fr);
    gap: 56px;
    padding-top: 56px;
  }
  .page-about .about-index {
    position: sticky;
    top: 24px;
    align-self: start;
  }
  .page-about .about-index .toc {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    padding: 0;
    border-left: 1px solid var(--grid);
  }
  .page-about .about-index .toc a {
    justify-content: space-between;
    width: 100%;
    margin-left: -1px;
    padding: 11px 10px 11px 16px;
    border: 0;
    border-left: 2px solid transparent;
    background: transparent;
    white-space: normal;
  }
  .page-about .about-index .toc a[aria-current="true"] {
    background: transparent;
    color: var(--ink);
    font-weight: 700;
    border-left-color: var(--vermilion);
  }
  .page-about .about-index .toc a[aria-current="true"] .mono {
    color: var(--vermilion);
  }
  .page-about .about-timeline__item {
    padding-left: 34px;
  }
  .page-about .about-node__summary::before {
    left: -34px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-team__cell::before,
  .page-about .about-next__links a {
    transition: none;
  }
}