.page-about {
  --about-rail-w: 150px;
  --about-gap: 3.5rem;
  padding-bottom: 5rem;
}

.page-about .crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .5rem;
  margin: 1.5rem 0 2.25rem;
  font-size: .8125rem;
  font-family: var(--font-mono);
  letter-spacing: .06em;
  color: var(--sky-mist);
}

.page-about .crumbs a {
  color: var(--sky-mist);
  text-decoration: none;
}

.page-about .crumbs a:hover,
.page-about .crumbs a:focus-visible {
  color: var(--sky-cyan);
}

/* ---------- 封面 ---------- */
.page-about .about-cover {
  margin-bottom: 2.25rem;
}

.page-about .about-cover h1 {
  font-family: var(--font-cond);
  font-size: clamp(2.1rem, 7vw, 4rem);
  line-height: 1.02;
  letter-spacing: -0.02em;
  font-weight: 700;
  color: var(--sky-white);
  margin: .75rem 0 1.125rem;
  max-width: 22ch;
}

.page-about .about-cover .cover__lead {
  color: var(--sky-mist);
  font-size: 1.0625rem;
  line-height: 1.8;
  max-width: 62ch;
  margin: 0;
}

.page-about .about-facts {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  padding: 0;
  margin: 1.75rem 0 0;
}

.page-about .about-facts li {
  display: inline-flex;
  align-items: baseline;
  gap: .4rem;
  padding: .5rem .95rem;
  border: 1px solid var(--sky-line);
  border-radius: var(--r-pill);
  background: var(--sky-panel);
  font-size: .8125rem;
  color: var(--sky-mist);
}

.page-about .about-facts b {
  font-family: var(--font-cond);
  font-size: 1.375rem;
  line-height: 1;
  font-weight: 700;
  color: var(--sky-cyan);
  font-variant-numeric: tabular-nums;
}

/* ---------- 头图 ---------- */
.page-about .about-hero {
  margin: 0 0 3.25rem;
  border-radius: var(--r-lg);
  overflow: hidden;
  background: var(--sky-panel);
  border: 1px solid var(--sky-line);
  box-shadow: var(--shadow-panel);
}

.page-about .about-hero img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 2 / 1;
  object-fit: cover;
}

/* ---------- 分屏骨架 ---------- */
.page-about .about-split {
  display: block;
}

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

/* ---------- 年份刻度 ---------- */
.page-about .year-rail {
  margin-bottom: 2.5rem;
}

.page-about .year-rail__title {
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--sky-mist);
  margin: 0 0 .7rem;
}

.page-about .year-rail__list {
  list-style: none;
  display: flex;
  gap: .45rem;
  margin: 0;
  padding: 0 0 .5rem;
  overflow-x: auto;
  scrollbar-width: none;
}

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

.page-about .year-rail__link {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 .95rem;
  border-radius: var(--r-pill);
  border: 1px solid var(--sky-line);
  background: var(--sky-panel);
  color: var(--sky-mist);
  font-family: var(--font-mono);
  font-size: .8125rem;
  letter-spacing: .06em;
  text-decoration: none;
  white-space: nowrap;
  transition: color .18s ease, border-color .18s ease, background .18s ease;
}

.page-about .year-rail__link:hover,
.page-about .year-rail__link:focus-visible {
  border-color: var(--sky-cyan);
  color: var(--sky-cyan);
  background: var(--sky-raise);
}

/* ---------- 章节 ---------- */
.page-about .about-block {
  margin-bottom: 4rem;
  scroll-margin-top: 6rem;
}

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

.page-about .about-block h2 {
  font-family: var(--font-cond);
  font-size: clamp(1.5rem, 4.2vw, 2.125rem);
  line-height: 1.15;
  letter-spacing: -0.01em;
  font-weight: 700;
  color: var(--sky-white);
  margin: 0 0 1rem;
  max-width: 26ch;
}

.page-about .about-block p {
  color: var(--sky-mist);
  font-size: 1rem;
  line-height: 1.8;
  max-width: 66ch;
  margin: 0 0 1rem;
}

/* ---------- 里程碑时间线 ---------- */
.page-about .milestones {
  list-style: none;
  margin: 2rem 0 0;
  padding: 0;
}

.page-about .milestone {
  position: relative;
  padding: 0 0 2.25rem 1.9rem;
  scroll-margin-top: 6.5rem;
}

.page-about .milestone::before {
  content: "";
  position: absolute;
  left: 0;
  top: .35rem;
  width: 13px;
  height: 13px;
  border-radius: 50%;
  border: 2px solid var(--sky-cyan);
  background: var(--sky-night);
  box-shadow: 0 0 0 5px rgba(43, 232, 210, .1);
}

.page-about .milestone::after {
  content: "";
  position: absolute;
  left: 6px;
  top: 1.7rem;
  bottom: .3rem;
  width: 1px;
  background: linear-gradient(to bottom, var(--sky-line), rgba(36, 54, 92, .15));
}

.page-about .milestone:last-child {
  padding-bottom: 0;
}

.page-about .milestone:last-child::after {
  display: none;
}

.page-about .milestone__year {
  font-family: var(--font-mono);
  font-size: .8125rem;
  letter-spacing: .12em;
  color: var(--sky-cyan);
  margin: 0 0 .35rem;
  font-variant-numeric: tabular-nums;
}

.page-about .milestone__title {
  font-family: var(--font-cond);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--sky-white);
  margin: 0 0 .5rem;
}

.page-about .milestone__text {
  color: var(--sky-mist);
  font-size: .9375rem;
  line-height: 1.78;
  margin: 0;
  max-width: 62ch;
}

/* ---------- 三条内容线 ---------- */
.page-about .about-lines {
  display: grid;
  gap: 1.25rem;
  margin-top: 1.75rem;
}

.page-about .about-lines__cards {
  display: grid;
  gap: 1rem;
}

.page-about .line-card {
  background: var(--sky-panel);
  border: 1px solid var(--sky-line);
  border-radius: var(--r-md);
  padding: 1.25rem 1.375rem;
  transition: border-color .18s ease, background .18s ease;
}

.page-about .line-card:hover {
  border-color: rgba(43, 232, 210, .45);
  background: var(--sky-raise);
}

.page-about .line-card p.line-card__tag {
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .12em;
  color: var(--sky-cyan);
  margin: 0 0 .6rem;
  max-width: none;
}

.page-about .line-card h3 {
  font-family: var(--font-cond);
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--sky-white);
  margin: 0 0 .5rem;
}

.page-about .line-card p {
  color: var(--sky-mist);
  font-size: .9375rem;
  line-height: 1.72;
  margin: 0;
  max-width: none;
}

.page-about .about-lines__figure {
  margin: 0;
  border-radius: var(--r-md);
  overflow: hidden;
  background: var(--sky-panel);
  border: 1px solid var(--sky-line);
}

.page-about .about-lines__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

.page-about .about-lines__figure figcaption {
  padding: .875rem 1.125rem;
  border-top: 1px solid var(--sky-line);
  font-size: .8125rem;
  line-height: 1.6;
  color: var(--sky-mist);
}

/* ---------- 团队构成 ---------- */
.page-about .team-bar {
  display: flex;
  gap: 4px;
  height: 14px;
  margin: 2rem 0 1.25rem;
  border-radius: var(--r-pill);
  overflow: hidden;
}

.page-about .team-bar__seg {
  flex-grow: var(--grow, 1);
  flex-basis: 0;
  border-radius: var(--r-pill);
}

.page-about .team-bar__seg--edit {
  background: linear-gradient(90deg, var(--sky-cyan), var(--sky-cyan-soft));
}

.page-about .team-bar__seg--write {
  background: linear-gradient(90deg, var(--sky-orange), var(--sky-orange-soft));
}

.page-about .team-legend {
  list-style: none;
  display: grid;
  gap: 1rem;
  padding: 0;
  margin: 0 0 1.5rem;
}

.page-about .team-legend__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-areas:
    "num label"
    "num desc";
  column-gap: .95rem;
  row-gap: .2rem;
  align-items: baseline;
  background: var(--sky-panel);
  border: 1px solid var(--sky-line);
  border-radius: var(--r-sm);
  padding: 1rem 1.25rem;
}

.page-about .team-legend__num {
  grid-area: num;
  font-family: var(--font-cond);
  font-size: 2.25rem;
  line-height: 1;
  font-weight: 700;
  color: var(--sky-cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .team-legend__item--write .team-legend__num {
  color: var(--sky-orange);
}

.page-about .team-legend__label {
  grid-area: label;
  color: var(--sky-white);
  font-weight: 700;
  font-size: .9375rem;
}

.page-about .team-legend__desc {
  grid-area: desc;
  color: var(--sky-mist);
  font-size: .875rem;
  line-height: 1.65;
}

/* ---------- 区域覆盖 ---------- */
.page-about .about-region {
  position: relative;
  overflow: hidden;
  border-radius: var(--r-lg);
  border: 1px solid var(--sky-line);
  background: var(--sky-panel);
  margin-top: 1.75rem;
}

.page-about .about-region__bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: .2;
}

.page-about .about-region__inner {
  position: relative;
  z-index: 1;
  padding: 2.25rem 1.5rem;
  background: linear-gradient(160deg, rgba(7, 14, 31, .7) 0%, rgba(4, 9, 20, .9) 100%);
}

.page-about .about-region__tag {
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--sky-orange);
  margin: 0 0 .7rem;
  max-width: none;
}

.page-about .about-region__inner h3 {
  font-family: var(--font-cond);
  font-size: clamp(1.25rem, 3.4vw, 1.75rem);
  font-weight: 700;
  color: var(--sky-white);
  margin: 0 0 .7rem;
}

.page-about .about-region__inner p {
  color: var(--sky-mist);
  font-size: .9375rem;
  line-height: 1.78;
  margin: 0;
  max-width: 56ch;
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  border-top: 1px solid var(--sky-line);
  padding-top: 2.5rem;
}

.page-about .next-links {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
  padding: 0;
  margin: 1.5rem 0 0;
}

.page-about .next-links a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 1.35rem;
  border-radius: var(--r-pill);
  border: 1px solid var(--sky-line);
  background: var(--sky-panel);
  color: var(--sky-white);
  text-decoration: none;
  font-size: .9375rem;
  transition: color .18s ease, border-color .18s ease, background .18s ease;
}

.page-about .next-links a:hover,
.page-about .next-links a:focus-visible {
  border-color: var(--sky-cyan);
  color: var(--sky-cyan);
  background: var(--sky-raise);
}

/* ---------- 平板与桌面 ---------- */
@media (min-width: 720px) {
  .page-about .team-legend {
    grid-template-columns: 1fr 1fr;
    gap: 1.25rem;
  }

  .page-about .about-region__inner {
    padding: 2.75rem 2.25rem;
  }
}

@media (min-width: 960px) {
  .page-about .about-split {
    display: grid;
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: var(--about-gap);
    align-items: start;
  }

  .page-about .year-rail {
    position: sticky;
    top: 7.5rem;
    margin-bottom: 0;
    padding-right: .5rem;
  }

  .page-about .year-rail__list {
    flex-direction: column;
    overflow: visible;
    gap: .15rem;
    padding: 0;
    position: relative;
  }

  .page-about .year-rail__list::before {
    content: "";
    position: absolute;
    left: 7px;
    top: 1.1rem;
    bottom: 1.1rem;
    width: 1px;
    background: var(--sky-line);
  }

  .page-about .year-rail__link {
    border: 0;
    background: none;
    border-radius: var(--r-sm);
    min-height: 42px;
    padding: .5rem .6rem .5rem 1.75rem;
    position: relative;
  }

  .page-about .year-rail__link::before {
    content: "";
    position: absolute;
    left: 3px;
    top: 50%;
    transform: translateY(-50%);
    width: 9px;
    height: 9px;
    border-radius: 50%;
    border: 1px solid var(--sky-line);
    background: var(--sky-night);
    transition: background .18s ease, border-color .18s ease;
  }

  .page-about .year-rail__link:hover,
  .page-about .year-rail__link:focus-visible {
    background: var(--sky-panel);
  }

  .page-about .year-rail__link:hover::before,
  .page-about .year-rail__link:focus-visible::before {
    background: var(--sky-cyan);
    border-color: var(--sky-cyan);
  }

  .page-about .about-lines {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
    gap: 2rem;
    align-items: start;
  }

  .page-about .about-block {
    margin-bottom: 5rem;
  }

  .page-about .about-hero {
    margin-bottom: 4rem;
  }
}

@media (min-width: 1200px) {
  .page-about {
    --about-rail-w: 168px;
    --about-gap: 4.5rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .line-card,
  .page-about .year-rail__link,
  .page-about .next-links a,
  .page-about .year-rail__link::before {
    transition: none;
  }
}

.page-about {
  --grow: inherit;
}