.page-about {
  background: var(--bg);
  color: var(--ink);
  overflow-x: hidden;
}

/* ---------- 首屏 ---------- */

.page-about .about-mast {
  position: relative;
  overflow: hidden;
  padding: calc(var(--header-h) + 40px) 0 clamp(32px, 6vw, 64px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-mast::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 76px 76px;
  opacity: 0.28;
  -webkit-mask-image: radial-gradient(120% 95% at 82% 4%, #000 0%, transparent 72%);
  mask-image: radial-gradient(120% 95% at 82% 4%, #000 0%, transparent 72%);
  pointer-events: none;
}

.page-about .about-mast::after {
  content: "";
  position: absolute;
  top: -110px;
  right: -140px;
  width: 460px;
  height: 460px;
  border-radius: 50%;
  background: radial-gradient(circle, var(--season-wash) 0%, transparent 68%);
  pointer-events: none;
}

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

.page-about .about-kicker {
  margin: 22px 0 0;
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--season-accent);
}

.page-about .about-title {
  margin: 16px 0 0;
  font-size: clamp(2.2rem, 8.4vw, 5.6rem);
  font-weight: 200;
  line-height: 1.04;
  letter-spacing: -0.02em;
  max-width: 16em;
}

.page-about .about-title em {
  display: block;
  font-style: normal;
  font-weight: 300;
  color: var(--ink);
  background: linear-gradient(96deg, var(--season-accent), var(--season-alt));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.page-about .about-intro {
  margin: 26px 0 0;
  max-width: 46em;
  font-size: clamp(1rem, 1.6vw, 1.125rem);
  line-height: 1.85;
  color: #D5DDEA;
}

.page-about .about-stats {
  list-style: none;
  margin: 32px 0 0;
  padding: 22px 0 0;
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  gap: 14px 38px;
}

.page-about .about-stats li {
  display: flex;
  align-items: baseline;
  gap: 9px;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--ink-dim);
}

.page-about .about-stats .num {
  font-size: clamp(1.15rem, 2.8vw, 1.55rem);
  font-weight: 700;
  color: var(--ink);
}

/* ---------- 主体骨架：侧栏索引 + 正文流 ---------- */

.page-about .about-body {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(24px, 5vw, 44px);
  padding-top: clamp(34px, 6vw, 64px);
  padding-bottom: clamp(56px, 10vw, 120px);
}

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

.page-about .rail-label {
  margin: 0 0 10px;
  font-size: 10px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--ink-dim);
}

.page-about .rail-list {
  list-style: none;
  margin: 0;
  padding: 0 0 6px;
  display: flex;
  gap: 18px;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .rail-list li {
  flex: none;
}

.page-about .rail-list a {
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  padding: 6px 0;
  font-size: 13px;
  line-height: 1.2;
  white-space: nowrap;
  text-decoration: none;
  color: var(--ink-dim);
  border-bottom: 2px solid transparent;
  transition: color 0.25s var(--ease), border-color 0.25s var(--ease);
}

.page-about .rail-list a:hover,
.page-about .rail-list a:focus-visible {
  color: var(--ink);
  border-bottom-color: var(--season-accent);
}

.page-about .rail-list .num {
  font-size: 11px;
  font-weight: 700;
  color: var(--season-accent);
}

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

/* ---------- 章节 ---------- */

.page-about .chapter {
  scroll-margin-top: calc(var(--header-h) + 24px);
}

.page-about .chapter + .chapter {
  margin-top: clamp(56px, 9vw, 104px);
}

.page-about .chapter-head {
  display: flex;
  align-items: flex-end;
  gap: 14px;
  padding-bottom: 14px;
  margin-bottom: 24px;
  border-bottom: 1px solid var(--line);
}

.page-about .chapter-num {
  flex: none;
  font-family: var(--font-num);
  font-size: clamp(2rem, 6.4vw, 3.6rem);
  font-weight: 700;
  line-height: 0.82;
  color: var(--season-accent);
  opacity: 0.42;
}

.page-about .chapter-headtext {
  min-width: 0;
  padding-bottom: 4px;
}

.page-about .chapter-tag {
  margin: 0 0 5px;
  font-size: 10px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--ink-dim);
}

.page-about .chapter-head h2 {
  margin: 0;
  font-size: clamp(1.4rem, 3.6vw, 2.3rem);
  font-weight: 600;
  line-height: 1.24;
  letter-spacing: -0.01em;
}

.page-about .chapter-text {
  max-width: 46em;
  margin: 0 0 18px;
  font-size: clamp(1rem, 1.4vw, 1.0625rem);
  line-height: 1.85;
  color: #D5DDEA;
}

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

.page-about .pull-quote {
  margin: 28px 0;
  padding: 22px 24px;
  max-width: 40em;
  border: 1px solid var(--line);
  border-left: 4px solid var(--season-alt);
  background: linear-gradient(100deg, var(--season-wash), transparent 78%);
  font-size: clamp(1.05rem, 2.6vw, 1.3rem);
  line-height: 1.65;
  font-weight: 300;
  color: var(--ink);
}

/* ---------- 图片 ---------- */

.page-about .about-figure {
  position: relative;
  margin: 0 0 26px;
  border: 1px solid var(--line);
  background: var(--panel);
  overflow: hidden;
}

.page-about .about-figure--wide {
  aspect-ratio: 16 / 9;
}

.page-about .about-figure--tall {
  aspect-ratio: 3 / 2;
}

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

.page-about .about-figure .media-cap {
  position: absolute;
  left: 0;
  bottom: 0;
  right: 0;
  padding: 10px 14px;
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--ink);
  background: linear-gradient(0deg, rgba(10, 17, 32, 0.92), rgba(10, 17, 32, 0));
}

/* ---------- 团队 ---------- */

.page-about .team-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
  margin-top: 28px;
}

.page-about .team-card {
  padding: 20px 20px 22px;
  background: #EEF3F9;
  color: #0A1120;
  border: 1px solid #0A1120;
  border-top: 4px solid var(--season-accent);
  box-shadow: 7px 7px 0 rgba(10, 17, 32, 0.6);
}

.page-about .team-tag {
  margin: 0 0 10px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: #5A6B87;
}

.page-about .team-card h3 {
  margin: 0 0 10px;
  font-size: 1.0625rem;
  font-weight: 600;
  line-height: 1.45;
  color: #0A1120;
}

.page-about .team-card p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: #35415A;
}

/* ---------- 数据链路 ---------- */

.page-about .process {
  display: grid;
  grid-template-columns: 1fr;
  gap: 22px;
  margin-top: 26px;
}

.page-about .process-steps {
  list-style: none;
  counter-reset: step;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .process-steps li {
  position: relative;
  padding: 16px 18px 16px 56px;
  background: var(--panel);
  border: 1px solid var(--line);
}

.page-about .process-steps li::before {
  counter-increment: step;
  content: "0" counter(step);
  position: absolute;
  left: 18px;
  top: 16px;
  font-family: var(--font-num);
  font-size: 13px;
  font-weight: 700;
  color: var(--season-accent);
}

.page-about .process-steps strong {
  display: block;
  margin-bottom: 6px;
  font-size: 1rem;
  font-weight: 600;
  color: var(--ink);
}

.page-about .process-steps span {
  display: block;
  font-size: 0.9375rem;
  line-height: 1.72;
  color: #C3CDDE;
}

/* ---------- 四季四联图 ---------- */

.page-about .season-strip {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  margin: 26px 0 18px;
}

.page-about .season-tile {
  position: relative;
  margin: 0;
  overflow: hidden;
  background: var(--panel);
  border: 1px solid var(--line);
  border-top-width: 3px;
}

.page-about .season-tile--spring { border-top-color: var(--spring); }
.page-about .season-tile--summer { border-top-color: var(--blue); }
.page-about .season-tile--autumn { border-top-color: var(--autumn-red); }
.page-about .season-tile--winter { border-top-color: #8FB6D8; }

.page-about .season-tile img {
  display: block;
  width: 100%;
  height: 100%;
  aspect-ratio: 4 / 5;
  object-fit: cover;
  transition: transform 0.55s var(--ease);
}

.page-about .season-tile:hover img,
.page-about .season-tile:focus-within img {
  transform: scale(1.07);
}

.page-about .season-tile figcaption {
  position: absolute;
  left: 10px;
  bottom: 10px;
  padding: 4px 9px;
  font-size: 10px;
  letter-spacing: 0.16em;
  color: var(--ink);
  background: rgba(10, 17, 32, 0.78);
  border: 1px solid rgba(242, 246, 250, 0.28);
}

.page-about .about-season-switch {
  margin: 0 0 24px;
}

/* ---------- 时间轴 ---------- */

.page-about .timeline {
  display: flex;
  gap: 14px;
  overflow-x: auto;
  padding: 10px 2px 20px;
  scroll-snap-type: x mandatory;
  scrollbar-width: thin;
  -webkit-overflow-scrolling: touch;
}

.page-about .tl-card {
  flex: 0 0 min(272px, 76vw);
  scroll-snap-align: start;
  padding: 20px 18px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-bottom: 3px solid var(--season-accent);
  box-shadow: 5px 5px 0 rgba(0, 0, 0, 0.36);
}

.page-about .tl-stage {
  margin: 0 0 10px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--season-accent);
}

.page-about .tl-card h3 {
  margin: 0 0 10px;
  font-size: 1.0625rem;
  font-weight: 600;
  line-height: 1.45;
  color: var(--ink);
}

.page-about .tl-card p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: #C3CDDE;
}

/* ---------- 功能演进 ---------- */

.page-about .version-list {
  margin-top: 26px;
  border-top: 1px solid var(--line);
}

.page-about .version-item {
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
  padding: 20px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .version-item h3 {
  margin: 0;
  font-size: 1.0625rem;
  font-weight: 600;
  line-height: 1.45;
  color: var(--ink);
}

.page-about .version-item h3::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  margin-right: 10px;
  vertical-align: 1px;
  background: var(--season-alt);
}

.page-about .version-item p {
  margin: 0;
  max-width: 46em;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: #C3CDDE;
}

/* ---------- 官方入口 ---------- */

.page-about .entry-block {
  margin-top: 26px;
  padding: clamp(20px, 4vw, 34px);
  background: var(--panel);
  border: 1px solid var(--line);
  border-left: 4px solid var(--season-accent);
}

.page-about .entry-list {
  margin: 0;
  display: grid;
  gap: 16px;
}

.page-about .entry-row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 4px;
}

.page-about .entry-row dt {
  font-size: 10px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--ink-dim);
}

.page-about .entry-row dd {
  margin: 0;
  font-size: 1rem;
  line-height: 1.6;
  color: var(--ink);
  word-break: break-word;
}

.page-about .entry-note {
  margin: 22px 0 0;
  padding-top: 18px;
  border-top: 1px dashed var(--line);
  max-width: 44em;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: #C3CDDE;
}

.page-about .about-cta {
  margin-top: 28px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 平板 ---------- */

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

  .page-about .team-card:nth-child(2) {
    margin-top: 34px;
  }

  .page-about .team-card:nth-child(3) {
    margin-top: 68px;
  }

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

  .page-about .season-tile img {
    aspect-ratio: 3 / 4;
  }

  .page-about .entry-row {
    grid-template-columns: 150px minmax(0, 1fr);
    gap: 4px 20px;
    align-items: baseline;
  }

  .page-about .version-item {
    grid-template-columns: 210px minmax(0, 1fr);
    gap: 0 28px;
    align-items: baseline;
  }
}

/* ---------- 桌面 ---------- */

@media (min-width: 1024px) {
  .page-about .about-body {
    grid-template-columns: 188px minmax(0, 1fr);
    gap: clamp(36px, 6vw, 84px);
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h) + 32px);
    padding-left: 18px;
    border-left: 1px solid var(--line);
  }

  .page-about .rail-list {
    flex-direction: column;
    gap: 2px;
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .rail-list a {
    border-bottom: 0;
    border-left: 2px solid transparent;
    padding: 7px 0 7px 10px;
    margin-left: -2px;
    transition: color 0.25s var(--ease), border-color 0.25s var(--ease);
  }

  .page-about .rail-list a:hover,
  .page-about .rail-list a:focus-visible {
    border-left-color: var(--season-accent);
    border-bottom-color: transparent;
  }

  .page-about .process {
    grid-template-columns: minmax(0, 0.85fr) minmax(0, 1.15fr);
    gap: clamp(24px, 4vw, 46px);
    align-items: start;
  }

  .page-about .about-figure--tall {
    aspect-ratio: 4 / 5;
    margin-bottom: 0;
  }

  .page-about .about-figure--wide {
    aspect-ratio: 21 / 9;
  }

  .page-about .chapter-text {
    font-size: 1.0625rem;
  }
}

@media (min-width: 1280px) {
  .page-about .about-body {
    grid-template-columns: 210px minmax(0, 1fr);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .season-tile img,
  .page-about .rail-list a {
    transition: none;
  }
}