.page-about {
  --about-rail: 1.5rem;
  --about-chapter-pad: clamp(2.25rem, 5vw, 3.75rem);
}

@media (min-width: 900px) {
  .page-about {
    --about-rail: 2.75rem;
  }
}

.page-about .about-hero {
  padding-top: clamp(1rem, 3vw, 2rem);
}

.page-about .about-hero-grid {
  display: grid;
  gap: clamp(1.5rem, 4vw, 3rem);
}

@media (min-width: 980px) {
  .page-about .about-hero-grid {
    grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr);
    align-items: start;
  }
}

.page-about h1 {
  margin: .55rem 0 1rem;
  font-family: var(--font-display);
  font-size: clamp(2rem, 5.2vw, 3.5rem);
  line-height: 1.08;
  letter-spacing: -.02em;
  color: var(--white);
}

.page-about .lede {
  max-width: 40ch;
  color: var(--mist);
  font-size: clamp(1rem, 1.5vw, 1.05rem);
  line-height: 1.85;
}

.page-about .about-aside-title {
  margin: 0 0 .85rem;
  font-family: var(--font-mono, monospace);
  font-size: .78rem;
  letter-spacing: .22em;
  color: var(--cyan);
}

.page-about .about-hero-aside .chapter-nav {
  border-top: var(--line-w) solid var(--line);
}

.page-about .about-facts {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  margin: clamp(1.75rem, 4vw, 2.75rem) 0 0;
  padding: 0;
  list-style: none;
  border: var(--line-w) solid var(--line);
  background: var(--ink-1);
}

.page-about .about-facts li {
  padding: .9rem 1.1rem;
  border-bottom: var(--line-w) solid var(--line);
  font-size: .93rem;
  line-height: 1.6;
  color: var(--mist);
}

.page-about .about-facts li:last-child {
  border-bottom: 0;
}

.page-about .about-fact-num {
  font-family: var(--font-mono, monospace);
  font-size: .98rem;
  color: var(--cyan);
}

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

  .page-about .about-facts li {
    border-bottom: 0;
    border-right: var(--line-w) solid var(--line);
  }

  .page-about .about-facts li:last-child {
    border-right: 0;
  }
}

/* ---------- 章节骨架：左侧竖线 + 节点 ---------- */

.page-about .about-spine {
  position: relative;
  margin-top: clamp(2rem, 5vw, 3.5rem);
}

.page-about .about-spine::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: calc(var(--about-rail) / 2 - 1px);
  width: 2px;
  background: linear-gradient(180deg, transparent, var(--line) 4%, var(--line) 96%, transparent);
}

.page-about .about-chapter {
  position: relative;
  padding-left: var(--about-rail);
  padding-block: var(--about-chapter-pad);
}

.page-about .about-node {
  position: absolute;
  left: calc(var(--about-rail) / 2 - 5px);
  top: calc(var(--about-chapter-pad) + .45rem);
  width: 10px;
  height: 10px;
  background: var(--ink-0);
  border: 2px solid var(--cyan);
  transform: rotate(45deg);
  z-index: 1;
}

.page-about .about-chapter-inner {
  min-width: 0;
}

.page-about .about-chapter-head {
  display: grid;
  gap: .5rem;
  margin-bottom: clamp(1.15rem, 2.5vw, 1.9rem);
}

@media (min-width: 900px) {
  .page-about .about-chapter-head {
    grid-template-columns: auto minmax(0, 1fr);
    align-items: end;
    gap: 1.75rem;
  }
}

.page-about .chapter-index {
  display: block;
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 7vw, 5rem);
  font-weight: 800;
  line-height: .82;
  letter-spacing: -.04em;
  color: var(--line);
}

@supports (-webkit-text-stroke: 1px #000) {
  .page-about .chapter-index {
    color: transparent;
    -webkit-text-stroke: 2px var(--line);
  }
}

.page-about .about-chapter-title .section-title {
  margin: .35rem 0 0;
}

.page-about .about-prose p {
  margin: 0 0 1rem;
  color: var(--mist);
  font-size: .99rem;
  line-height: 1.85;
}

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

.page-about .about-lead {
  max-width: 46ch;
  margin: 0 0 clamp(1.25rem, 3vw, 2rem);
  color: var(--mist);
  font-size: .99rem;
  line-height: 1.85;
}

.page-about .about-pull {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: .5rem 1rem;
  margin-top: clamp(1.25rem, 3vw, 1.9rem);
  padding: 1rem 1.2rem;
  border: var(--line-w) solid var(--line);
  border-left: 4px solid var(--orange);
  background: var(--ink-2);
}

.page-about .about-pull-label {
  font-family: var(--font-mono, monospace);
  font-size: .82rem;
  letter-spacing: .12em;
  color: var(--orange);
}

.page-about .about-pull-text {
  color: var(--white);
  font-size: .98rem;
}

/* ---------- 交替双栏 ---------- */

.page-about .about-duo {
  display: grid;
  gap: clamp(1.5rem, 3.5vw, 2.5rem);
  align-items: start;
}

@media (min-width: 900px) {
  .page-about .about-duo {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
  }

  .page-about .about-duo--flip {
    grid-template-columns: minmax(0, .92fr) minmax(0, 1.08fr);
    align-items: center;
  }
}

.page-about .about-figure {
  margin: 0;
}

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

/* ---------- 三道关 ---------- */

.page-about .about-steps {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 1.15rem;
}

.page-about .about-steps li {
  position: relative;
  padding: 0 0 1.15rem 3rem;
  border-bottom: var(--line-w) solid var(--line);
}

.page-about .about-steps li:last-child {
  padding-bottom: 0;
  border-bottom: 0;
}

.page-about .about-steps h3 {
  margin: 0 0 .4rem;
  font-family: var(--font-display);
  font-size: 1.1rem;
  letter-spacing: .01em;
  color: var(--white);
}

.page-about .about-steps p {
  margin: 0;
  color: var(--mist);
  font-size: .96rem;
  line-height: 1.8;
}

.page-about .about-step-num {
  position: absolute;
  left: 0;
  top: .18rem;
  font-family: var(--font-mono, monospace);
  font-size: .92rem;
  font-weight: 700;
  color: var(--cyan);
}

/* ---------- 四象限团队卡 ---------- */

.page-about .about-quad {
  display: grid;
  gap: var(--gutter);
}

@media (min-width: 700px) {
  .page-about .about-quad {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1200px) {
  .page-about .about-quad {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .about-quad-card {
  position: relative;
  padding: 1.5rem 1.2rem 1.35rem;
  border: var(--line-w) solid var(--line);
  background: var(--ink-2);
  box-shadow: var(--shadow-hard);
  transition: transform .24s ease, border-color .24s ease;
}

.page-about .about-quad-card:hover,
.page-about .about-quad-card:focus-within {
  transform: translate(-3px, -3px);
  border-color: var(--cyan);
}

.page-about .about-quad-mark {
  display: block;
  margin-bottom: .8rem;
  font-family: var(--font-mono, monospace);
  font-size: 1.5rem;
  font-weight: 700;
  line-height: 1;
  color: var(--cyan);
}

.page-about .about-quad-card h3 {
  margin: 0 0 .55rem;
  font-family: var(--font-display);
  font-size: 1.15rem;
  color: var(--white);
}

.page-about .about-quad-card p {
  margin: 0;
  color: var(--mist);
  font-size: .94rem;
  line-height: 1.75;
}

/* ---------- 覆盖范围信息图 ---------- */

.page-about .about-coverage {
  display: grid;
  gap: clamp(1.5rem, 3vw, 2.5rem);
}

@media (min-width: 900px) {
  .page-about .about-coverage {
    grid-template-columns: minmax(0, .85fr) minmax(0, 1.15fr);
    align-items: center;
  }
}

.page-about .about-matrix-wrap {
  position: relative;
  overflow: hidden;
  padding: clamp(1.25rem, 3vw, 2rem);
  border: var(--line-w) solid var(--line);
  background: var(--ink-1);
  box-shadow: var(--shadow-hard);
}

.page-about .about-matrix {
  position: absolute;
  inset: 0;
  background-image: radial-gradient(rgba(43, 231, 208, .8) 1.5px, transparent 1.6px);
  background-size: 20px 20px;
  opacity: .35;
  -webkit-mask-image: radial-gradient(circle at 28% 25%, #000 18%, transparent 74%);
  mask-image: radial-gradient(circle at 28% 25%, #000 18%, transparent 74%);
  pointer-events: none;
}

.page-about .about-matrix-figures {
  position: relative;
  display: grid;
  gap: 1rem;
}

.page-about .about-matrix-row {
  display: flex;
  align-items: baseline;
  gap: .85rem;
  padding-bottom: .9rem;
  border-bottom: var(--line-w) solid var(--line);
}

.page-about .about-matrix-row:last-child {
  padding-bottom: 0;
  border-bottom: 0;
}

.page-about .about-matrix-num {
  font-family: var(--font-mono, monospace);
  font-size: clamp(2rem, 5.5vw, 3rem);
  font-weight: 700;
  line-height: 1;
  color: var(--cyan);
}

.page-about .about-matrix-label {
  color: var(--white);
  font-size: .95rem;
}

.page-about .about-coverage-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 1rem;
}

.page-about .about-coverage-list li {
  position: relative;
  padding-left: 1.4rem;
  color: var(--mist);
  font-size: .96rem;
  line-height: 1.8;
}

.page-about .about-coverage-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .68em;
  width: 8px;
  height: 8px;
  background: var(--cyan);
  transform: rotate(45deg);
}

/* ---------- 时间轴 ---------- */

.page-about .about-track {
  position: relative;
  margin: 0 0 clamp(1.75rem, 4vw, 2.75rem);
  padding: 0;
  list-style: none;
}

.page-about .about-track::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 1.9rem;
  bottom: 1.7rem;
  width: 2px;
  background: var(--line);
}

.page-about .about-track-item {
  position: relative;
  padding: 1.15rem 0 1.15rem 2rem;
  border-bottom: var(--line-w) solid var(--line);
}

.page-about .about-track-item:last-child {
  border-bottom: 0;
}

.page-about .about-track-item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 1.6rem;
  width: 10px;
  height: 10px;
  background: var(--ink-0);
  border: 2px solid var(--cyan);
  transform: rotate(45deg);
  transition: background .24s ease, border-color .24s ease;
}

.page-about .about-track-item:hover::before,
.page-about .about-track-item:focus-within::before {
  background: var(--cyan-soft);
  border-color: var(--cyan-soft);
}

.page-about .about-track-item[data-current="true"]::before {
  background: var(--orange);
  border-color: var(--orange);
}

.page-about .about-track-phase {
  margin: 0 0 .3rem;
  font-family: var(--font-mono, monospace);
  font-size: .8rem;
  letter-spacing: .16em;
  color: var(--cyan);
}

.page-about .about-track-item[data-current="true"] .about-track-phase {
  color: var(--orange);
}

.page-about .about-track-item h3 {
  margin: 0 0 .4rem;
  font-family: var(--font-display);
  font-size: 1.1rem;
  color: var(--white);
}

.page-about .about-track-item p {
  margin: 0;
  max-width: 62ch;
  color: var(--mist);
  font-size: .95rem;
  line-height: 1.8;
}

.page-about .about-figure--band {
  width: 100%;
}

/* ---------- 合作卡 ---------- */

.page-about .about-partners {
  margin-top: clamp(1rem, 2.5vw, 1.75rem);
}

.page-about .about-partner-card {
  display: flex;
  flex-direction: column;
}

.page-about .about-partner-kicker {
  margin: 0 0 .65rem;
  font-family: var(--font-mono, monospace);
  font-size: .78rem;
  letter-spacing: .14em;
  color: var(--cyan);
}

.page-about .about-partner-text {
  margin: .7rem 0 0;
  color: var(--mist);
  font-size: .94rem;
  line-height: 1.78;
}

/* ---------- 本地服务按钮组 ---------- */

.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: .85rem;
  margin-top: clamp(1.25rem, 3vw, 1.75rem);
}

/* ---------- 结尾跳转 ---------- */

.page-about .about-next {
  border-top: var(--line-w) solid var(--line);
  background: linear-gradient(180deg, rgba(15, 23, 51, .9), var(--ink-0));
}

.page-about .about-next-grid {
  display: grid;
  gap: clamp(1.5rem, 3vw, 2.5rem);
}

@media (min-width: 900px) {
  .page-about .about-next-grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.2fr);
    align-items: center;
  }
}

.page-about .about-next-links {
  display: grid;
  gap: var(--gutter);
}

@media (min-width: 640px) {
  .page-about .about-next-links {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.page-about .about-next-card {
  display: grid;
  gap: .55rem;
  text-decoration: none;
  color: var(--white);
  transition: transform .24s ease, border-color .24s ease;
}

.page-about .about-next-card:hover,
.page-about .about-next-card:focus-visible {
  transform: translate(-3px, -3px);
  border-color: var(--cyan);
}

.page-about .about-next-kicker {
  font-family: var(--font-mono, monospace);
  font-size: .78rem;
  letter-spacing: .14em;
  color: var(--cyan);
}

.page-about .about-next-card strong {
  font-family: var(--font-display);
  font-size: 1.08rem;
  line-height: 1.4;
}

.page-about .about-next-more {
  font-size: .88rem;
  color: var(--orange);
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-quad-card,
  .page-about .about-track-item::before,
  .page-about .about-next-card {
    transition: none;
  }

  .page-about .about-quad-card:hover,
  .page-about .about-quad-card:focus-within,
  .page-about .about-next-card:hover,
  .page-about .about-next-card:focus-visible {
    transform: none;
  }
}