.page-about {
  --about-nav-w: 236px;
  --about-gap: clamp(32px, 5vw, 68px);
  --about-accent: var(--signal-orange);
  color: var(--paper);
}

.page-about .about-sec[id] {
  scroll-margin-top: calc(var(--header-h) + 32px);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding: clamp(20px, 4vw, 44px) 0 clamp(32px, 6vw, 64px);
  position: relative;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  inset: auto 0 0 0;
  height: 1px;
  background: linear-gradient(90deg, var(--signal-orange), var(--pulse-green) 42%, transparent 84%);
  opacity: .55;
}

.page-about .about-hero__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(26px, 4vw, 48px);
  align-items: center;
}

.page-about h1 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(30px, 5.4vw, 58px);
  line-height: 1.16;
  letter-spacing: -0.01em;
  margin: 0 0 18px;
  color: var(--paper);
}

.page-about .lede {
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.8;
  color: var(--mist);
  margin: 0 0 26px;
  max-width: 60ch;
}

.page-about .about-hero__facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.page-about .about-hero__fact {
  background: var(--ink-deep);
  padding: 15px 16px 14px;
  border-left: 2px solid var(--about-accent);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);
  transition: background-color .18s ease;
}

.page-about .about-hero__fact:hover {
  background: var(--ink-layer);
}

.page-about .about-hero__fact .k {
  display: block;
  font-family: var(--font-data);
  font-weight: 700;
  font-size: clamp(22px, 3.2vw, 30px);
  line-height: 1;
  color: var(--paper);
  font-variant-numeric: tabular-nums;
}

.page-about .about-hero__fact .v {
  display: block;
  margin-top: 7px;
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--mist);
}

.page-about .about-hero__media {
  border-radius: var(--radius-card);
}

/* ---------- 正文骨架 ---------- */
.page-about .about-body {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--about-gap);
  padding-bottom: clamp(48px, 8vw, 96px);
}

/* ---------- 章节导航 ---------- */
.page-about .about-toc__title {
  font-family: var(--font-data);
  font-size: 11px;
  letter-spacing: .16em;
  color: var(--mist);
  margin: 0 0 12px;
  padding-left: 12px;
}

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

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

.page-about .about-toc__list li {
  flex: 0 0 auto;
}

.page-about .about-toc__link {
  display: block;
  padding: 8px 14px;
  font-size: 13.5px;
  color: var(--mist);
  text-decoration: none;
  border: 1px solid var(--line-rock);
  border-radius: var(--radius-pill);
  white-space: nowrap;
  transition: color .15s ease, border-color .15s ease, background-color .15s ease;
}

.page-about .about-toc__link:hover,
.page-about .about-toc__link:focus-visible {
  color: var(--paper);
  border-color: var(--about-accent);
  background: var(--ink-layer);
}

/* ---------- 章节 ---------- */
.page-about .about-sec {
  margin-bottom: clamp(52px, 7vw, 92px);
}

.page-about .about-sec:last-of-type {
  margin-bottom: clamp(36px, 5vw, 60px);
}

.page-about .about-sec h2 {
  font-family: var(--font-head);
  font-weight: 800;
  font-size: clamp(22px, 3.2vw, 33px);
  line-height: 1.28;
  letter-spacing: -0.01em;
  margin: 0 0 16px;
  color: var(--paper);
}

.page-about .about-sec h2::before {
  content: "";
  display: block;
  width: 36px;
  height: 3px;
  margin-bottom: 14px;
  background: var(--about-accent);
  clip-path: polygon(0 0, 100% 0, calc(100% - 7px) 100%, 0 100%);
}

.page-about .about-sec p {
  font-size: 16px;
  line-height: 1.8;
  color: var(--mist);
  margin: 0 0 14px;
  max-width: 70ch;
}

.page-about .about-sec p strong {
  color: var(--paper);
  font-weight: 600;
}

.page-about .about-sec h3 {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 16px;
  line-height: 1.4;
  margin: 0 0 6px;
  color: var(--paper);
}

/* ---------- 年份刻度时间线 ---------- */
.page-about .about-tl-wrap {
  margin-top: 30px;
  padding-top: 12px;
  border-top: 1px solid var(--line-rock);
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-tl {
  display: block;
  width: 100%;
  min-width: 600px;
  height: auto;
}

.page-about .about-tl__axis {
  stroke: var(--line-rock);
  stroke-width: 3;
}

.page-about .about-tl__tick {
  stroke: var(--line-rock);
  stroke-width: 2;
  stroke-dasharray: 3 6;
}

.page-about .about-tl circle {
  fill: var(--ink-void);
  stroke: var(--about-accent);
  stroke-width: 3;
  transition: fill .18s ease, stroke .18s ease;
}

.page-about .about-tl circle.is-current {
  fill: var(--pulse-green);
  stroke: var(--pulse-green);
}

.page-about .about-tl g:hover circle {
  fill: var(--about-accent);
}

.page-about .about-tl text {
  font-family: var(--font-data);
  font-weight: 600;
  font-size: 26px;
  fill: var(--paper);
  text-anchor: middle;
  font-variant-numeric: tabular-nums;
}

.page-about .about-tl text.about-tl__sub {
  font-family: var(--font-body);
  font-weight: 400;
  font-size: 17px;
  fill: var(--mist);
  letter-spacing: .02em;
}

/* ---------- 团队分工 ---------- */
.page-about .about-roster {
  margin-top: 26px;
  border-top: 1px solid var(--line-rock);
}

.page-about .about-roster__row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 8px;
  padding: 20px 0 22px;
  border-bottom: 1px solid var(--line-rock);
  transition: background-color .18s ease, padding-left .18s ease;
}

.page-about .about-roster__row:hover {
  background: rgba(23, 33, 64, .6);
  padding-left: 12px;
}

.page-about .about-roster__num {
  font-family: var(--font-data);
  font-weight: 700;
  font-size: clamp(30px, 4.6vw, 40px);
  line-height: 1;
  color: var(--paper);
  font-variant-numeric: tabular-nums;
}

.page-about .about-roster__body p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--mist);
}

.page-about .about-roster__tag {
  justify-self: start;
}

/* ---------- 关键数字 ---------- */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-top: 28px;
}

.page-about .about-stat {
  padding: 20px 18px 18px;
  background: linear-gradient(155deg, var(--ink-deep) 0%, var(--ink-layer) 100%);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 18px), calc(100% - 18px) 100%, 0 100%);
}

.page-about .about-stat__num {
  display: block;
  font-family: var(--font-data);
  font-weight: 700;
  font-size: clamp(34px, 6.4vw, 62px);
  line-height: 1;
  color: var(--paper);
  font-variant-numeric: tabular-nums;
}

.page-about .about-stat__num em {
  font-style: normal;
  font-size: .36em;
  font-weight: 500;
  color: var(--about-accent);
  margin-left: 6px;
  letter-spacing: .04em;
}

.page-about .about-stat__cap {
  display: block;
  margin-top: 12px;
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--mist);
}

/* ---------- 版本演进 ---------- */
.page-about .about-ver__media {
  margin: 22px 0 32px;
  border-radius: var(--radius-card);
}

.page-about .about-ver {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}

.page-about .about-ver::before {
  content: "";
  position: absolute;
  left: 11px;
  top: 10px;
  bottom: 10px;
  width: 2px;
  background: linear-gradient(180deg, var(--clay), var(--moss) 48%, var(--pulse-green));
  opacity: .7;
}

.page-about .about-ver__item {
  --ver-accent: var(--about-accent);
  position: relative;
  padding: 0 0 28px 44px;
}

.page-about .about-ver__item:last-child {
  padding-bottom: 4px;
}

.page-about .about-ver__item--clay { --ver-accent: var(--clay); }
.page-about .about-ver__item--moss { --ver-accent: var(--moss); }
.page-about .about-ver__item--pulse { --ver-accent: var(--pulse-green); }

.page-about .about-ver__item::before {
  content: "";
  position: absolute;
  left: 3px;
  top: 6px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--ink-void);
  border: 3px solid var(--ver-accent);
  transition: background-color .18s ease;
}

.page-about .about-ver__item:hover::before {
  background: var(--ver-accent);
}

.page-about .about-ver__head {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 8px;
}

.page-about .about-ver__year {
  font-family: var(--font-data);
  font-weight: 700;
  font-size: clamp(22px, 3vw, 26px);
  line-height: 1;
  color: var(--paper);
  font-variant-numeric: tabular-nums;
}

.page-about .about-ver__tag {
  font-family: var(--font-data);
  font-size: 11.5px;
  letter-spacing: .06em;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  background: var(--ver-accent);
  color: var(--ink-void);
  white-space: nowrap;
}

.page-about .about-ver__item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--mist);
}

.page-about .about-ver__note {
  margin-top: 22px;
  font-size: 13.5px;
  line-height: 1.7;
}

/* ---------- 合作与认可 ---------- */
.page-about .about-sec--eco {
  position: relative;
  overflow: hidden;
  padding: clamp(24px, 4vw, 44px) clamp(20px, 3.6vw, 40px);
  border-radius: var(--radius-card);
  background: var(--ink-deep);
  border-top: 2px solid var(--moss);
}

.page-about .about-eco__bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: .18;
  pointer-events: none;
}

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

.page-about .about-sec--eco h2 {
  color: var(--paper);
}

/* ---------- 三条坚持 ---------- */
.page-about .about-pledge {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
  margin-top: 26px;
}

.page-about .about-pledge__card {
  padding: 24px 20px 22px;
  background: var(--ink-deep);
  border-top: 2px solid var(--about-accent);
  border-radius: var(--radius-card);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 20px), calc(100% - 20px) 100%, 0 100%);
  transition: background-color .18s ease, transform .18s ease;
}

.page-about .about-pledge__card:hover {
  background: var(--ink-layer);
  transform: translateY(-3px);
}

.page-about .about-pledge__no {
  display: block;
  font-family: var(--font-data);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--about-accent);
  margin-bottom: 12px;
}

.page-about .about-pledge__card p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--mist);
}

/* ---------- 后续入口 ---------- */
.page-about .about-next {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  margin-top: clamp(24px, 4vw, 44px);
}

.page-about .about-next__card {
  display: block;
  padding: 18px 20px;
  text-decoration: none;
  background: var(--ink-deep);
  border-left: 3px solid var(--line-rock);
  border-radius: 0 12px 12px 0;
  transition: border-color .18s ease, background-color .18s ease, transform .18s ease;
}

.page-about .about-next__card:hover,
.page-about .about-next__card:focus-visible {
  border-left-color: var(--about-accent);
  background: var(--ink-layer);
  transform: translateX(4px);
}

.page-about .about-next__label {
  display: block;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 15.5px;
  color: var(--paper);
  margin-bottom: 5px;
}

.page-about .about-next__desc {
  display: block;
  font-size: 13px;
  line-height: 1.65;
  color: var(--mist);
}

/* ---------- 返回顶部 ---------- */
.page-about .about-backtop {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  margin-top: 30px;
  padding: 9px 16px 9px 12px;
  font-size: 13.5px;
  color: var(--mist);
  text-decoration: none;
  border: 1px solid var(--line-rock);
  border-radius: var(--radius-pill);
  transition: color .15s ease, border-color .15s ease;
}

.page-about .about-backtop:hover,
.page-about .about-backtop:focus-visible {
  color: var(--paper);
  border-color: var(--pulse-green);
}

.page-about .about-backtop__dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--pulse-green);
  box-shadow: 0 0 0 0 rgba(155, 255, 77, .55);
  animation: about-pulse 2s ease-out infinite;
}

@keyframes about-pulse {
  0%   { box-shadow: 0 0 0 0 rgba(155, 255, 77, .5); }
  70%  { box-shadow: 0 0 0 10px rgba(155, 255, 77, 0); }
  100% { box-shadow: 0 0 0 0 rgba(155, 255, 77, 0); }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-backtop__dot { animation: none; }
  .page-about .about-pledge__card:hover,
  .page-about .about-next__card:hover { transform: none; }
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .about-roster__row {
    grid-template-columns: 92px minmax(0, 1fr) auto;
    align-items: start;
    column-gap: 22px;
    row-gap: 0;
  }

  .page-about .about-roster__tag {
    justify-self: end;
    margin-top: 2px;
  }

  .page-about .about-next {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-pledge {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 960px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.06fr) minmax(0, .94fr);
  }
}

@media (min-width: 1000px) {
  .page-about .about-body {
    grid-template-columns: var(--about-nav-w) minmax(0, 1fr);
  }

  .page-about .about-toc {
    position: sticky;
    top: calc(var(--header-h) + 24px);
    align-self: start;
  }

  .page-about .about-toc__list {
    display: grid;
    gap: 2px;
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .about-toc__link {
    border: 0;
    border-left: 2px solid transparent;
    border-radius: 0 8px 8px 0;
    padding: 9px 12px;
    white-space: normal;
    line-height: 1.5;
  }

  .page-about .about-toc__link:hover,
  .page-about .about-toc__link:focus-visible {
    border-left-color: var(--about-accent);
  }
}

@media (max-width: 420px) {
  .page-about .about-hero__facts {
    grid-template-columns: 1fr;
  }

  .page-about .about-stats {
    grid-template-columns: 1fr;
  }

  .page-about .about-tl {
    min-width: 520px;
  }
}