.page-about {
  --about-rail: 4.5rem;
  --about-gap: clamp(3.5rem, 9vw, 7.5rem);
  --about-hair: 1px solid var(--fb-line);
  overflow-x: hidden;
}

/* ---------- 面包屑留白 ---------- */
.page-about .fb-crumbs {
  padding-top: clamp(1.25rem, 3vw, 2rem);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding-block: clamp(2rem, 5vw, 3.5rem) clamp(3rem, 7vw, 5.5rem);
  background:
    radial-gradient(1100px 460px at 82% -18%, rgba(43, 227, 196, 0.10), transparent 62%),
    radial-gradient(760px 380px at 8% 110%, rgba(255, 122, 26, 0.07), transparent 60%);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: linear-gradient(90deg, var(--fb-cyan), transparent 70%);
  opacity: .5;
}

.page-about .about-vertical {
  display: block;
  font-family: var(--fb-mono);
  font-size: var(--fs-13);
  letter-spacing: .18em;
  color: var(--fb-mist);
  margin-bottom: 1.25rem;
}

.page-about .about-hero__title {
  max-width: 16ch;
  margin-top: .75rem;
}

.page-about .about-hero__body {
  display: grid;
  gap: 1.75rem;
  margin-top: clamp(1.5rem, 4vw, 2.5rem);
}

.page-about .about-hero__aside {
  border-left: 1px solid var(--fb-cyan);
  padding-left: 1.25rem;
}

.page-about .about-hero__note {
  margin: 0;
  font-size: var(--fs-14);
  line-height: 1.85;
  color: var(--fb-mist);
  max-width: 34em;
}

.page-about .about-hero__meta {
  list-style: none;
  margin: 1.25rem 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
}

.page-about .about-figures {
  list-style: none;
  margin: clamp(2.5rem, 6vw, 4rem) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.5rem 1.25rem;
}

.page-about .about-figures > li {
  border-top: var(--about-hair);
  padding-top: .9rem;
  min-width: 0;
}

.page-about .about-figures__num {
  display: block;
  font-size: clamp(1.75rem, 4.6vw, 2.5rem);
  line-height: 1.05;
  color: var(--fb-white);
}

.page-about .about-figures__label {
  display: block;
  margin-top: .5rem;
  font-size: var(--fs-13);
  line-height: 1.6;
  color: var(--fb-mist);
}

/* ---------- 目录 ---------- */
.page-about .about-toc {
  margin-top: var(--about-gap);
  padding-block: 1.25rem;
  border-top: var(--about-hair);
  border-bottom: var(--about-hair);
}

.page-about .about-toc .fb-toc__list {
  display: flex;
  gap: 1.5rem;
  overflow-x: auto;
  padding-bottom: .35rem;
  scrollbar-width: thin;
}

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

.page-about .about-toc .fb-toc__link {
  font-size: var(--fs-14);
  white-space: nowrap;
}

/* ---------- 章节通用 ---------- */
.page-about .fb-section {
  padding-block: var(--about-gap);
}

.page-about .fb-section .fb-kicker {
  margin-bottom: .75rem;
}

.page-about .fb-section .fb-lede {
  margin-top: 1.25rem;
}

/* 左栏纵向注释 */
.page-about .about-rail {
  display: grid;
  gap: 1rem;
}

.page-about .about-rail__note {
  margin: 0;
  font-family: var(--fb-mono);
  font-size: var(--fs-13);
  letter-spacing: .2em;
  color: var(--fb-cyan);
}

.page-about .about-rail__body > .fb-lede {
  max-width: 36em;
}

/* ---------- 比赛日流程 ---------- */
.page-about .about-steps {
  list-style: none;
  margin: clamp(2rem, 5vw, 3rem) 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .about-steps__item {
  position: relative;
  padding: 1.5rem 0 1.5rem 1.75rem;
  border-left: var(--about-hair);
}

.page-about .about-steps__item::before {
  content: "";
  position: absolute;
  left: -3.5px;
  top: 1.95rem;
  width: 7px;
  height: 7px;
  background: var(--fb-cyan);
}

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

.page-about .about-steps__no {
  display: block;
  font-size: var(--fs-22);
  color: var(--fb-cyan-soft);
  line-height: 1;
  margin-bottom: .6rem;
}

.page-about .about-steps__item h3 {
  margin: 0 0 .5rem;
  font-size: var(--fs-18);
  color: var(--fb-white);
  letter-spacing: .01em;
}

.page-about .about-steps__item p {
  margin: 0;
  font-size: var(--fs-16);
  line-height: 1.75;
  color: var(--fb-mist);
  max-width: 36em;
}

/* ---------- 时间线 ---------- */
.page-about .about-anchor {
  margin: clamp(2rem, 5vw, 3.25rem) 0 0;
}

.page-about .about-timeline {
  list-style: none;
  margin: clamp(2.5rem, 6vw, 4rem) 0 0;
  padding: 0;
}

.page-about .about-timeline__item {
  position: relative;
  display: grid;
  gap: .5rem;
  padding: 1.5rem 0 1.5rem 1.5rem;
  border-left: var(--about-hair);
}

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: -3.5px;
  top: 2.35rem;
  width: 7px;
  height: 7px;
  background: var(--fb-orange);
}

.page-about .about-timeline__item:first-child {
  padding-top: 0;
}

.page-about .about-timeline__item:first-child::before {
  top: .85rem;
}

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

.page-about .about-timeline__year {
  font-size: clamp(1.75rem, 5vw, 2.25rem);
  color: var(--fb-orange);
  line-height: 1;
}

.page-about .about-timeline__text h3 {
  margin: 0 0 .5rem;
  font-size: var(--fs-22);
  color: var(--fb-white);
}

.page-about .about-timeline__text p {
  margin: 0;
  font-size: var(--fs-16);
  line-height: 1.75;
  color: var(--fb-mist);
  max-width: 40em;
}

/* ---------- 团队 ---------- */
.page-about .about-split {
  display: grid;
  gap: clamp(2rem, 5vw, 3.5rem);
  align-items: start;
}

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

.page-about .about-roles {
  list-style: none;
  margin: clamp(1.75rem, 4vw, 2.5rem) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.75rem 1.25rem;
}

.page-about .about-roles__item {
  border-top: var(--about-hair);
  padding-top: 1rem;
  min-width: 0;
}

.page-about .about-roles__num {
  display: block;
  font-size: clamp(1.5rem, 4vw, 2rem);
  color: var(--fb-cyan);
  line-height: 1;
}

.page-about .about-roles__item h3 {
  margin: .65rem 0 .4rem;
  font-size: var(--fs-16);
  color: var(--fb-white);
}

.page-about .about-roles__item p {
  margin: 0;
  font-size: var(--fs-14);
  line-height: 1.7;
  color: var(--fb-mist);
}

/* ---------- 数据来源 ---------- */
.page-about .about-sources {
  margin-top: clamp(2rem, 5vw, 3rem);
  padding: clamp(1.5rem, 4vw, 2.5rem) clamp(1.25rem, 3.5vw, 2rem);
  display: grid;
  gap: 2rem;
  border: var(--about-hair);
}

.page-about .about-sources__lead p {
  margin: 0 0 1rem;
  font-size: var(--fs-16);
  line-height: 1.8;
  color: var(--fb-white);
  max-width: 38em;
}

.page-about .about-sources__lead p:last-child {
  margin-bottom: 0;
  color: var(--fb-mist);
}

.page-about .about-sources__stats {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.5rem 1rem;
}

.page-about .about-sources__stats > li {
  min-width: 0;
}

.page-about .about-sources__stats .fb-num {
  display: block;
  font-size: clamp(1.6rem, 4.2vw, 2.25rem);
  line-height: 1;
  color: var(--fb-cyan);
}

.page-about .about-sources__small {
  font-size: .55em;
  margin-left: .15em;
  color: inherit;
}

.page-about .about-sources__unit {
  display: block;
  margin-top: .55rem;
  font-size: var(--fs-13);
  line-height: 1.55;
  color: var(--fb-mist);
}

/* ---------- 合作生态 ---------- */
.page-about .about-partners {
  margin-top: clamp(2rem, 5vw, 3rem);
  display: grid;
  gap: clamp(2rem, 5vw, 3rem);
  align-items: start;
}

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

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

.page-about .about-partners__list > li {
  border-top: var(--about-hair);
  padding-top: 1.1rem;
}

.page-about .about-partners__list h3 {
  margin: 0 0 .5rem;
  font-size: var(--fs-18);
  color: var(--fb-white);
}

.page-about .about-partners__list p {
  margin: 0;
  font-size: var(--fs-16);
  line-height: 1.75;
  color: var(--fb-mist);
  max-width: 36em;
}

/* ---------- 规模与认可 ---------- */
.page-about .about-scale {
  list-style: none;
  margin: clamp(2rem, 5vw, 3rem) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.75rem 1.25rem;
}

.page-about .about-scale > li {
  border-top: 1px solid var(--fb-line);
  padding-top: 1rem;
  min-width: 0;
}

.page-about .about-scale__num {
  display: block;
  font-size: clamp(1.9rem, 5.2vw, 2.75rem);
  line-height: 1;
  color: var(--fb-white);
}

.page-about .about-scale__small {
  font-size: .52em;
  margin-left: .18em;
  color: var(--fb-cyan-soft);
}

.page-about .about-scale__label {
  display: block;
  margin-top: .55rem;
  font-size: var(--fs-13);
  line-height: 1.55;
  color: var(--fb-mist);
}

.page-about .about-cta {
  margin-top: clamp(2.5rem, 6vw, 4rem);
  padding-top: clamp(1.5rem, 4vw, 2.25rem);
  border-top: 1px solid var(--fb-line);
  display: grid;
  gap: 1.5rem;
}

.page-about .about-cta__text {
  margin: 0;
  font-size: var(--fs-18);
  line-height: 1.7;
  color: var(--fb-white);
  max-width: 32em;
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
}

.page-about .about-cta__actions .fb-btn {
  text-decoration: none;
}

/* ---------- 图片容器补充 ---------- */
.page-about .fb-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
}

/* ---------- 平板及以上 ---------- */
@media (min-width: 720px) {
  .page-about .about-figures {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-sources {
    grid-template-columns: minmax(0, 1.25fr) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-partners {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr);
  }

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

  .page-about .about-cta {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
  }
}

/* ---------- 桌面 ---------- */
@media (min-width: 900px) {
  .page-about .about-hero {
    padding-block: clamp(2.5rem, 5vw, 4rem) clamp(4rem, 8vw, 7rem);
  }

  .page-about .about-hero__body {
    grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr);
    gap: 3rem;
    align-items: start;
  }

  .page-about .about-rail {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: 2.5rem;
  }

  .page-about .about-rail__note {
    writing-mode: vertical-rl;
    transform: rotate(180deg);
    justify-self: start;
    padding-top: .25rem;
  }

  .page-about .about-steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: 3rem;
  }

  .page-about .about-steps__item:last-child {
    padding-bottom: 1.5rem;
  }

  .page-about .about-timeline__item {
    grid-template-columns: 8rem minmax(0, 1fr);
    column-gap: 2.5rem;
    padding: 2rem 0 2rem 2.25rem;
  }

  .page-about .about-timeline__item::before {
    top: 2.85rem;
  }

  .page-about .about-timeline__item:first-child::before {
    top: .85rem;
  }

  .page-about .about-split {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
    gap: 4rem;
  }

  .page-about .about-roles {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-vertical {
    position: absolute;
    top: clamp(2.5rem, 5vw, 4rem);
    right: 0;
    writing-mode: vertical-rl;
    margin: 0;
  }
}

@media (min-width: 1100px) {
  .page-about .about-steps {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .fb-reveal {
    transition: none;
  }
}