.page-about {
  --about-line-x: 28px;
  --about-gutter: 88px;
  background: var(--ink);
  color: var(--warm);
  overflow-x: clip;
}

/* ---------- Hero ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding-block: clamp(28px, 6vw, 60px) clamp(36px, 6vw, 64px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  top: -30%;
  right: -14%;
  width: min(620px, 72vw);
  height: 168%;
  background: var(--panel);
  transform: skewX(-13deg);
  pointer-events: none;
}

.page-about .about-hero-inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(28px, 5vw, 52px);
  grid-template-columns: minmax(0, 1fr);
}

.page-about .about-hero .crumbs {
  margin-bottom: 22px;
}

.page-about .about-hero .eyebrow {
  margin: 0;
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--mint);
}

.page-about .about-hero h1 {
  margin: 16px 0 0;
  font-size: clamp(34px, 7.6vw, 72px);
  line-height: 1.04;
  letter-spacing: -.02em;
  font-weight: 800;
  color: var(--warm);
  max-width: 14em;
}

.page-about .about-lede {
  margin: clamp(18px, 3vw, 26px) 0 0;
  max-width: 32em;
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.8;
  color: var(--steel);
}

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

.page-about .about-fact {
  background: var(--ink);
  padding: 16px 16px 18px;
}

.page-about .about-fact dt {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .12em;
  color: var(--stone);
}

.page-about .about-fact dd {
  margin: 0;
  font-size: 14px;
  font-weight: 600;
  line-height: 1.55;
  color: var(--warm);
}

@media (min-width: 920px) {
  .page-about .about-hero-inner {
    grid-template-columns: minmax(0, 8fr) minmax(0, 4fr);
    align-items: end;
  }

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

/* ---------- 主体布局 ---------- */
.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(22px, 4vw, 40px);
  padding-block: clamp(32px, 6vw, 64px) clamp(40px, 7vw, 80px);
}

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

.page-about .about-toc .toc-title {
  margin: 0 0 10px;
  font-size: 11px;
  letter-spacing: .16em;
  color: var(--stone);
  text-transform: uppercase;
}

.page-about .about-toc .toc-list {
  display: flex;
  gap: 8px;
  margin: 0;
  padding: 0 0 4px;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: none;
}

.page-about .about-toc .toc-list::-webkit-scrollbar {
  display: none;
}

.page-about .about-toc .toc-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  white-space: nowrap;
  padding: 9px 15px;
  border-radius: var(--radius-pill);
  border: 1px solid var(--line);
  color: var(--steel);
  font-size: 13px;
  line-height: 1.4;
  text-decoration: none;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background var(--dur) var(--ease);
}

.page-about .about-toc .toc-link .mono {
  font-size: 11px;
  color: var(--clay);
  transition: color var(--dur) var(--ease);
}

.page-about .about-toc .toc-link:hover {
  border-color: var(--line-strong);
  color: var(--warm);
}

.page-about .about-toc .toc-link.is-active {
  color: var(--warm);
  border-color: rgba(255, 106, 43, .55);
  background: rgba(255, 106, 43, .14);
}

.page-about .about-toc .toc-link.is-active .mono {
  color: var(--orange);
}

/* ---------- 竖线时间轴 ---------- */
.page-about .about-flow {
  min-width: 0;
}

@media (min-width: 900px) {
  .page-about .about-flow {
    position: relative;
    padding-left: var(--about-gutter);
  }

  .page-about .about-flow::before {
    content: "";
    position: absolute;
    left: var(--about-line-x);
    top: 8px;
    bottom: 8px;
    width: 1px;
    background: linear-gradient(180deg, var(--clay) 0%, rgba(169, 188, 205, .38) 16%, rgba(169, 188, 205, .18) 84%, transparent 100%);
  }
}

/* ---------- 章节 ---------- */
.page-about .about-chapter {
  position: relative;
  padding-block: clamp(22px, 4vw, 40px);
}

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

.page-about .chapter-head {
  position: relative;
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 16px;
}

.page-about .chapter-node {
  flex: none;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .04em;
  color: var(--warm);
  background: var(--panel);
  border: 1px solid var(--clay);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}

.page-about .about-chapter h2 {
  margin: 0;
  font-size: clamp(25px, 3.6vw, 40px);
  line-height: 1.14;
  letter-spacing: -.02em;
  font-weight: 800;
  color: var(--warm);
}

.page-about .about-chapter:target .chapter-node {
  border-color: var(--orange);
  color: var(--orange);
  box-shadow: 0 0 0 5px rgba(255, 106, 43, .14);
}

@media (min-width: 900px) {
  .page-about .chapter-head {
    display: block;
    margin-bottom: 18px;
  }

  .page-about .chapter-node {
    position: absolute;
    left: calc(var(--about-line-x) - var(--about-gutter) - 15px);
    top: 2px;
  }
}

/* ---------- 正文窄栏 ---------- */
.page-about .about-measure {
  max-width: 36em;
}

.page-about .about-measure > p {
  margin: 0 0 14px;
  font-size: 16px;
  line-height: 1.85;
  color: var(--steel);
}

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

@media (min-width: 700px) {
  .page-about .about-measure > p {
    font-size: 17px;
  }
}

/* ---------- 图片 ---------- */
.page-about .about-figure {
  margin: clamp(22px, 3.5vw, 32px) 0 0;
}

.page-about .about-figure .img-frame {
  border-radius: var(--radius-card);
  border: 1px solid var(--line);
  overflow: hidden;
}

.page-about .about-cap {
  margin: 12px 0 0;
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--stone);
}

/* ---------- 折叠时间轴 ---------- */
.page-about .fold {
  margin-top: clamp(20px, 3vw, 26px);
  border: 1px solid var(--line);
  border-radius: var(--radius-card);
  background: var(--panel);
  overflow: hidden;
}

.page-about .fold summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  cursor: pointer;
  padding: 16px 18px;
  font-size: 14px;
  font-weight: 600;
  color: var(--mint);
  list-style: none;
}

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

.page-about .fold summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 16px;
  line-height: 1;
  color: var(--orange);
}

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

.page-about .fold-body {
  padding: 2px 18px 18px;
}

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

.page-about .about-timeline li {
  display: grid;
  grid-template-columns: 84px minmax(0, 1fr);
  gap: 14px;
  padding: 14px 0;
  border-top: 1px solid var(--line);
}

.page-about .about-timeline li:first-child {
  border-top: 0;
  padding-top: 4px;
}

.page-about .about-tl-date {
  font-size: 11px;
  letter-spacing: .08em;
  color: var(--clay);
  padding-top: 3px;
}

.page-about .about-timeline p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--steel);
}

@media (max-width: 520px) {
  .page-about .about-timeline li {
    grid-template-columns: minmax(0, 1fr);
    gap: 6px;
  }
}

/* ---------- 三层结构卡 ---------- */
.page-about .about-layers {
  list-style: none;
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
  grid-template-columns: minmax(0, 1fr);
}

.page-about .about-layers li {
  background: var(--panel);
  border-radius: var(--radius-card);
  border: 1px solid var(--line);
  border-left: 3px solid var(--clay);
  padding: 20px 18px 22px;
  transition: transform var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .about-layers li:nth-child(2) {
  border-left-color: var(--orange);
}

.page-about .about-layers li:nth-child(3) {
  border-left-color: var(--moss);
}

.page-about .layer-tag {
  margin: 0 0 10px;
  font-size: 11px;
  letter-spacing: .12em;
  color: var(--stone);
}

.page-about .about-layers h3 {
  margin: 0 0 8px;
  font-size: 18px;
  line-height: 1.35;
  font-weight: 700;
  color: var(--warm);
}

.page-about .about-layers li p:last-child {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--steel);
}

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

/* ---------- 团队 ---------- */
.page-about .about-teams {
  list-style: none;
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
  grid-template-columns: minmax(0, 1fr);
}

.page-about .about-teams li {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius-card);
  padding: 20px 18px 22px;
}

.page-about .team-count {
  display: flex;
  align-items: baseline;
  gap: 6px;
  margin-bottom: 6px;
}

.page-about .team-num {
  font-size: 42px;
  line-height: 1;
  font-weight: 800;
  letter-spacing: -.03em;
  color: var(--orange);
}

.page-about .team-unit {
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--stone);
}

.page-about .about-teams h3 {
  margin: 0 0 8px;
  font-size: 16px;
  font-weight: 700;
  color: var(--warm);
}

.page-about .about-teams li p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--steel);
}

@media (min-width: 720px) {
  .page-about .about-teams {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.page-about .about-pipeline {
  margin-top: clamp(20px, 3vw, 28px);
  padding: 20px 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius-card);
  background: rgba(19, 41, 63, .62);
}

.page-about .pipeline-title {
  margin: 0;
  font-size: 11px;
  letter-spacing: .14em;
  color: var(--stone);
}

.page-about .about-steps {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 10px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.page-about .about-steps li {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  border-radius: var(--radius-pill);
  background: var(--ink);
  border: 1px solid var(--line);
  font-size: 14px;
  color: var(--warm);
}

.page-about .about-steps li .mono {
  font-size: 11px;
  color: var(--orange);
}

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

/* ---------- 更新节奏 ---------- */
.page-about .about-cadence {
  list-style: none;
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

.page-about .about-cadence li {
  padding: 20px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .cadence-when {
  margin: 0;
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--clay);
}

.page-about .about-cadence h3 {
  margin: 8px 0 8px;
  font-size: 18px;
  font-weight: 700;
  color: var(--warm);
}

.page-about .about-cadence li p:last-child {
  margin: 0;
  max-width: 34em;
  font-size: 15px;
  line-height: 1.8;
  color: var(--steel);
}

.page-about .about-note {
  margin-top: clamp(20px, 3vw, 26px);
  padding: 18px 20px;
  border-left: 3px solid var(--mint);
  border-radius: 0 var(--radius-card) var(--radius-card) 0;
  background: rgba(127, 227, 196, .07);
}

.page-about .about-note p {
  margin: 0;
  font-size: 14px;
  line-height: 1.85;
  color: var(--steel);
}

.page-about .about-note .mono {
  color: var(--mint);
  font-size: 13px;
}

/* ---------- 原则 ---------- */
.page-about .about-principles {
  list-style: none;
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
}

.page-about .about-principles li {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 14px;
  padding: 18px 0;
  border-top: 1px solid var(--line);
}

.page-about .about-principles li:last-child {
  border-bottom: 1px solid var(--line);
}

.page-about .principle-num {
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--stone);
  padding-top: 5px;
}

.page-about .about-principles h3 {
  margin: 0 0 8px;
  font-size: 17px;
  line-height: 1.4;
  font-weight: 700;
  color: var(--warm);
}

.page-about .principle-body p {
  margin: 0 0 10px;
  max-width: 32em;
  font-size: 14px;
  line-height: 1.75;
  color: var(--steel);
}

.page-about .principle-link {
  display: inline-block;
  font-size: 13px;
  color: var(--mint);
  text-decoration: none;
  border-bottom: 1px solid var(--mint-line);
  opacity: .62;
  transition: opacity var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .about-principles li:hover .principle-link,
.page-about .about-principles li:focus-within .principle-link {
  opacity: 1;
  border-bottom-color: var(--mint);
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  padding-block: clamp(32px, 5vw, 56px) clamp(44px, 7vw, 88px);
  border-top: 1px solid var(--line);
}

.page-about .about-next-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: calc(var(--radius-card) + 6px);
  padding: clamp(22px, 4vw, 42px);
}

.page-about .about-next-tag {
  margin: 0;
  font-size: 11px;
  letter-spacing: .18em;
  color: var(--orange);
}

.page-about .about-next-card h2 {
  margin: 12px 0 0;
  max-width: 20em;
  font-size: clamp(23px, 3.2vw, 34px);
  line-height: 1.2;
  letter-spacing: -.02em;
  font-weight: 800;
  color: var(--warm);
}

.page-about .about-next-list {
  list-style: none;
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
  display: grid;
  gap: 10px;
  grid-template-columns: minmax(0, 1fr);
}

.page-about .about-next-list a {
  display: grid;
  grid-template-columns: 32px minmax(0, 1fr);
  row-gap: 4px;
  column-gap: 12px;
  padding: 15px 16px;
  border-radius: var(--radius-card);
  background: var(--ink);
  border: 1px solid var(--line);
  text-decoration: none;
  transition: transform var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .about-next-list a:hover {
  border-color: rgba(255, 106, 43, .5);
}

.page-about .about-next-list .mono {
  grid-row: 1 / span 2;
  align-self: start;
  padding-top: 3px;
  font-size: 11px;
  color: var(--orange);
}

.page-about .about-next-list strong {
  font-size: 15px;
  font-weight: 700;
  color: var(--warm);
}

.page-about .about-next-list a span:last-child {
  font-size: 13px;
  line-height: 1.55;
  color: var(--steel);
}

@media (min-width: 760px) {
  .page-about .about-next-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

/* ---------- 焦点与动效 ---------- */
.page-about a:focus-visible {
  outline: 2px solid var(--mint);
  outline-offset: 3px;
  border-radius: 4px;
}

@media (hover: hover) and (pointer: fine) {
  .page-about .about-layers li:hover,
  .page-about .about-next-list a:hover {
    transform: translateY(-2px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-layers li,
  .page-about .about-next-list a,
  .page-about .principle-link,
  .page-about .about-toc .toc-link,
  .page-about .chapter-node {
    transition: none;
  }

  .page-about .about-layers li:hover,
  .page-about .about-next-list a:hover {
    transform: none;
  }
}

/* ---------- 桌面侧栏 ---------- */
@media (min-width: 1000px) {
  .page-about .about-body {
    grid-template-columns: 232px minmax(0, 1fr);
    gap: clamp(32px, 4vw, 56px);
  }

  .page-about .about-rail {
    position: sticky;
    top: 84px;
    align-self: start;
  }

  .page-about .about-toc .toc-title {
    font-size: 11px;
  }

  .page-about .about-toc .toc-list {
    display: block;
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .about-toc .toc-link {
    display: flex;
    align-items: baseline;
    border: 0;
    border-left: 2px solid var(--line);
    border-radius: 0;
    background: none;
    padding: 9px 0 9px 15px;
    white-space: normal;
    font-size: 14px;
    line-height: 1.5;
    color: var(--steel);
  }

  .page-about .about-toc .toc-link:hover {
    color: var(--warm);
    border-left-color: var(--line-strong);
  }

  .page-about .about-toc .toc-link.is-active {
    background: none;
    color: var(--warm);
    border-left-color: var(--orange);
  }
}