.page-about {
  --about-body-w: 620px;
  --about-aside-w: 236px;
  padding-top: var(--head-h);
  background: var(--night);
  overflow-x: hidden;
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumbs-wrap {
  padding-top: clamp(18px, 3vw, 34px);
}

/* ---------- 首屏：分屏文字建筑 ---------- */
.page-about .about-hero {
  position: relative;
  padding: clamp(28px, 5vw, 60px) 0 0;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    repeating-linear-gradient(to right, var(--grid-line) 0 1px, transparent 1px 84px),
    repeating-linear-gradient(to bottom, var(--grid-line) 0 1px, transparent 1px 84px);
}

.page-about .about-hero-rail {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(26px, 5vw, 56px);
  align-items: end;
}

.page-about .about-h1 {
  margin: 14px 0 0;
  font-size: clamp(38px, 7.4vw, 76px);
  line-height: 1.04;
  letter-spacing: -0.02em;
}

.page-about .about-h1-sub {
  display: block;
  margin-top: 0.24em;
  font-size: 0.48em;
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--grey);
}

.page-about .about-lede {
  max-width: var(--about-body-w);
  margin: clamp(20px, 3vw, 30px) 0 0;
  font-size: 16px;
  line-height: 1.85;
  color: rgba(232, 238, 234, .9);
}

.page-about .about-facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(146px, 1fr));
  gap: 20px 24px;
  margin: clamp(26px, 4vw, 44px) 0 0;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}

.page-about .about-fact dt {
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--stone);
}

.page-about .about-fact dd {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 3px;
  margin: 8px 0 0;
}

.page-about .about-facts .num-lg {
  font-family: var(--mono);
  font-size: clamp(28px, 3.6vw, 40px);
  line-height: 1;
  color: var(--mint);
}

.page-about .about-facts .unit {
  color: var(--grey);
}

.page-about .about-fact-note {
  flex: 0 0 100%;
  margin-top: 5px;
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--grey);
}

.page-about .about-hero-fig {
  margin: 0;
}

.page-about .about-hero-fig img {
  display: block;
  width: 100%;
  height: clamp(260px, 46vh, 540px);
  object-fit: cover;
  border-left: 1px solid var(--line-strong);
  filter: saturate(.72) contrast(1.06) brightness(.92);
}

/* ---------- 章节骨架 ---------- */
.page-about .about-chapter {
  padding: clamp(56px, 8vw, 104px) 0 0;
}

.page-about .about-chapter--air {
  padding-top: clamp(88px, 13vw, 176px);
}

.page-about .about-chapter-grid {
  display: grid;
  gap: 20px;
}

.page-about .about-no {
  display: block;
  font-family: var(--mono);
  font-size: clamp(46px, 7vw, 82px);
  font-weight: 700;
  line-height: 0.82;
  letter-spacing: -0.05em;
  color: var(--stone);
  transition: color var(--t) var(--ease), transform var(--t) var(--ease);
}

@supports (-webkit-text-stroke: 1px #000) {
  .page-about .about-no {
    color: transparent;
    -webkit-text-stroke: 1px var(--stone);
  }
  .page-about .about-chapter-aside:hover .about-no {
    color: var(--mint);
    -webkit-text-stroke-color: var(--mint);
  }
}

.page-about .about-chapter-aside:hover .about-no {
  color: var(--mint);
  transform: translate(-3px, -2px);
}

.page-about .about-chapter-title {
  margin: 16px 0 0;
  font-size: clamp(19px, 2.1vw, 24px);
  line-height: 1.35;
  color: var(--white);
}

.page-about .about-chapter-aside .side-note {
  margin: 14px 0 0;
  font-size: 12px;
  line-height: 1.6;
  letter-spacing: 0.1em;
  color: var(--stone);
}

/* ---------- 正文窄栏 ---------- */
.page-about .about-chapter-body {
  max-width: var(--about-body-w);
  font-size: 15.5px;
  line-height: 1.85;
  color: rgba(232, 238, 234, .86);
}

.page-about .about-chapter-body p {
  margin: 0 0 1.15em;
}

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

.page-about .about-chapter-body a {
  color: var(--mint);
  text-decoration: none;
  border-bottom: 1px solid var(--line-strong);
  transition: border-color var(--t) var(--ease), color var(--t) var(--ease);
}

.page-about .about-chapter-body a:hover {
  border-bottom-color: var(--mint);
}

/* ---------- 术语悬停释义 ---------- */
.page-about .gloss {
  position: relative;
  display: inline-block;
  color: var(--white);
  border-bottom: 1px dashed var(--line-strong);
  cursor: help;
}

.page-about .gloss-tip {
  position: absolute;
  left: 0;
  bottom: calc(100% + 10px);
  z-index: 6;
  width: min(262px, 70vw);
  padding: 10px 12px;
  font-size: 12px;
  line-height: 1.65;
  color: var(--grey);
  background: var(--lamp);
  border: 1px solid var(--line-strong);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 180ms var(--ease), visibility 180ms var(--ease);
}

.page-about .gloss:hover .gloss-tip,
.page-about .gloss:focus .gloss-tip {
  opacity: 1;
  visibility: visible;
}

/* ---------- 四类内容条目 ---------- */
.page-about .about-lines {
  margin: 0 0 1.4em;
  padding: 0;
  list-style: none;
}

.page-about .about-lines li {
  position: relative;
  padding: 14px 0 14px 22px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-lines li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 25px;
  width: 11px;
  height: 1px;
  background: var(--mint);
}

.page-about .line-key {
  display: block;
  font-size: 15px;
  font-weight: 700;
  color: var(--white);
}

.page-about .line-text {
  display: block;
  margin-top: 3px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--grey);
}

/* ---------- 图片块 ---------- */
.page-about .about-figure {
  margin: clamp(26px, 4vw, 42px) 0 0;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  background: var(--turf);
  border: 1px solid var(--line);
}

.page-about .about-figure figcaption {
  margin-top: 10px;
  font-size: 12.5px;
  line-height: 1.7;
  letter-spacing: 0.03em;
  color: var(--stone);
}

/* ---------- 定位球四类战术 ---------- */
.page-about .about-tactics {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  margin: 0 0 1.4em;
}

.page-about .about-tactic {
  padding: 14px 14px 16px;
  background: var(--turf);
  border-left: 2px solid var(--mint);
}

.page-about .tactic-name {
  display: block;
  font-size: 15px;
  font-weight: 700;
  color: var(--white);
  letter-spacing: -0.01em;
}

.page-about .tactic-text {
  display: block;
  margin-top: 6px;
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--grey);
}

/* ---------- 分工条目 ---------- */
.page-about .about-roles {
  margin: 0 0 1.4em;
  padding: 0;
  list-style: none;
}

.page-about .about-roles li {
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr);
  gap: 6px 16px;
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .role-no {
  grid-row: span 2;
  font-family: var(--mono);
  font-size: clamp(26px, 3.4vw, 34px);
  font-weight: 700;
  line-height: 1;
  color: var(--violet);
}

.page-about .role-head {
  font-size: 15px;
  font-weight: 700;
  color: var(--white);
}

.page-about .role-text {
  grid-column: 2;
  margin: 0;
  font-size: 14px;
  line-height: 1.72;
  color: var(--grey);
}

/* ---------- 版本阶段折叠 ---------- */
.page-about .about-stages {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.page-about .about-stages > li {
  border-bottom: 1px solid var(--line);
}

.page-about .about-stage summary {
  display: flex;
  align-items: baseline;
  gap: 16px;
  padding: 18px 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about .stage-no {
  font-family: var(--mono);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--mint);
}

.page-about .stage-name {
  font-size: 15.5px;
  color: var(--white);
}

.page-about .stage-arrow {
  margin-left: auto;
  width: 9px;
  height: 9px;
  border-right: 1px solid var(--mint);
  border-bottom: 1px solid var(--mint);
  transform: rotate(45deg) translate(-2px, -2px);
  transition: transform var(--t) var(--ease);
}

.page-about .about-stage[open] .stage-arrow {
  transform: rotate(225deg) translate(-2px, -2px);
}

.page-about .stage-text {
  margin: 0 0 20px;
  padding-left: 20px;
  border-left: 1px solid var(--line-strong);
  font-size: 14px;
  line-height: 1.78;
  color: var(--grey);
}

/* ---------- 合规与联系 ---------- */
.page-about .about-contact {
  margin: 0 0 1.4em;
  border-top: 1px solid var(--line);
}

.page-about .contact-row {
  display: grid;
  grid-template-columns: 84px minmax(0, 1fr);
  gap: 4px 14px;
  padding: 13px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .contact-row dt {
  font-size: 12.5px;
  letter-spacing: 0.08em;
  color: var(--stone);
}

.page-about .contact-row dd {
  margin: 0;
  font-family: var(--mono);
  font-size: 14px;
  line-height: 1.6;
  color: var(--white);
  word-break: break-word;
}

/* ---------- 出口区 ---------- */
.page-about .about-exit {
  margin-top: clamp(70px, 10vw, 140px);
  padding: clamp(40px, 6vw, 72px) 0 0;
  border-top: 1px solid var(--line-strong);
}

.page-about .about-exit-links {
  display: grid;
  gap: 10px;
  margin-top: 18px;
}

.page-about .about-exit-links a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 20px;
  font-size: 15px;
  color: var(--white);
  text-decoration: none;
  background: var(--turf);
  border: 1px solid var(--line);
  transition: background var(--t) var(--ease), color var(--t) var(--ease), border-color var(--t) var(--ease);
}

.page-about .about-exit-links a::after {
  content: "→";
  color: var(--mint);
  transition: color var(--t) var(--ease);
}

.page-about .about-exit-links a:hover {
  background: var(--mint);
  color: var(--lamp);
  border-color: var(--mint);
}

.page-about .about-exit-links a:hover::after {
  color: var(--lamp);
}

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

/* ---------- 显现动效 ---------- */
.js .page-about [data-reveal] {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 240ms var(--ease), transform 240ms var(--ease);
}

.js .page-about [data-reveal].is-in {
  opacity: 1;
  transform: none;
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .about-exit-links {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .page-about .about-hero-rail {
    grid-template-columns: minmax(0, 1fr) minmax(220px, 29%);
    gap: clamp(44px, 6vw, 96px);
  }

  .page-about .about-chapter-grid {
    grid-template-columns: var(--about-aside-w) minmax(0, 1fr);
    gap: clamp(34px, 5vw, 76px);
    align-items: start;
  }

  .page-about .about-chapter-aside .side-note {
    writing-mode: vertical-rl;
    height: 128px;
    margin-top: 22px;
    letter-spacing: 0.22em;
    overflow: hidden;
  }

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

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

@media (min-width: 1180px) {
  .page-about {
    --about-body-w: 660px;
    --about-aside-w: 256px;
  }

  .page-about .about-figure--inset img {
    height: 340px;
  }
}

@media (max-width: 559px) {
  .page-about .about-tactics {
    grid-template-columns: minmax(0, 1fr);
  }

  .page-about .about-roles li {
    grid-template-columns: 44px minmax(0, 1fr);
  }

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