.page-about {
  --about-num-size: clamp(48px, 8.5vw, 116px);
  --about-sticky-top: calc(var(--yk-header-h) + 26px);
  --about-gap: clamp(20px, 3vw, 40px);
  background: var(--yk-deep);
  color: var(--yk-white);
  overflow-x: hidden;
}

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

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding-bottom: clamp(40px, 6vw, 76px);
  border-bottom: 1px solid var(--yk-line-soft);
  background:
    radial-gradient(120% 90% at 88% 0%, rgba(230, 57, 70, .14) 0%, transparent 58%),
    radial-gradient(90% 80% at 0% 100%, rgba(42, 157, 143, .10) 0%, transparent 60%),
    var(--yk-deep);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  inset: auto 0 -1px 0;
  height: 3px;
  background: linear-gradient(90deg, var(--yk-red) 0 25%, var(--yk-yellow) 25% 50%, var(--yk-teal) 50% 75%, var(--yk-gold) 75% 100%);
  opacity: .85;
}

.page-about .yk-breadcrumb {
  margin-bottom: clamp(24px, 4vw, 44px);
}

.page-about .yk-heading--xl {
  max-width: 20ch;
  margin: 14px 0 0;
}

.page-about .about-hero .yk-lede {
  max-width: 62ch;
  margin-top: clamp(16px, 2.4vw, 24px);
}

.page-about .about-hero__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: clamp(30px, 4.5vw, 52px) 0 0;
  background: var(--yk-line-soft);
  border: 1px solid var(--yk-line-soft);
}

.page-about .about-hero__stats > div {
  background: var(--yk-deep);
  padding: clamp(16px, 2vw, 22px) clamp(14px, 1.8vw, 20px);
}

.page-about .about-hero__stats dt {
  font-family: var(--yk-mono);
  font-size: 11px;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--yk-mist);
  margin-bottom: 10px;
}

.page-about .about-hero__stats dd {
  font-family: var(--yk-cond);
  font-size: clamp(24px, 3.4vw, 36px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: .01em;
  color: var(--yk-white);
  font-variant-numeric: tabular-nums;
}

/* ---------- 章节通用 ---------- */
.page-about .yk-chapter {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(10px, 2vw, 18px);
}

.page-about .yk-chapter__num {
  font-family: var(--yk-cond);
  font-size: var(--about-num-size);
  font-weight: 700;
  line-height: .8;
  letter-spacing: -.02em;
  color: rgba(244, 247, 251, .14);
  font-variant-numeric: tabular-nums;
}

.page-about .yk-chapter__num::after {
  content: "";
  display: block;
  width: 38px;
  height: 2px;
  margin-top: 14px;
  background: var(--yk-red);
}

.page-about .yk-chapter__body > .yk-heading {
  margin-bottom: clamp(14px, 2vw, 20px);
}

.page-about .yk-chapter__body > p {
  max-width: 68ch;
  color: rgba(244, 247, 251, .82);
}

.page-about .yk-chapter__body > p + p {
  margin-top: 1em;
}

/* ---------- 起源 ---------- */
.page-about .about-origin__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(26px, 4vw, 56px);
}

.page-about .about-origin__figure .yk-media__frame {
  border: 1px solid var(--yk-line);
  aspect-ratio: 16 / 9;
  overflow: hidden;
}

.page-about .about-origin__figure img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(.85) contrast(1.05);
}

/* ---------- 里程碑横条 ---------- */
.page-about .about-timeline {
  position: relative;
  margin-top: clamp(48px, 8vw, 104px);
  padding-top: clamp(44px, 7vw, 88px);
  background:
    linear-gradient(180deg, rgba(6, 11, 24, .9) 0%, rgba(11, 19, 43, .9) 100%),
    var(--yk-night);
  border-top: 1px solid var(--yk-line);
  border-bottom: 1px solid var(--yk-line);
}

.page-about .about-timeline__intro {
  margin-bottom: clamp(24px, 3.6vw, 40px);
}

.page-about .about-timeline__lede {
  max-width: 58ch;
  margin-top: clamp(12px, 2vw, 18px);
  color: var(--yk-mist);
}

.page-about .about-milestones__rail {
  display: flex;
  gap: 0;
  overflow-x: auto;
  border-bottom: 1px solid var(--yk-line);
  scrollbar-width: thin;
}

.page-about .about-milestones__tab {
  flex: 0 0 auto;
  appearance: none;
  background: transparent;
  border: 0;
  border-bottom: 2px solid transparent;
  padding: 14px clamp(18px, 2.6vw, 30px);
  font-family: var(--yk-mono);
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--yk-mist);
  cursor: pointer;
  transition: color .28s var(--yk-ease), border-color .28s var(--yk-ease), background .28s var(--yk-ease);
}

.page-about .about-milestones__tab:hover {
  color: var(--yk-white);
  background: rgba(244, 247, 251, .04);
}

.page-about .about-milestones__tab[aria-selected="true"] {
  color: var(--yk-white);
  border-bottom-color: var(--yk-red);
}

.page-about .about-milestones__tab:focus-visible {
  outline: 2px solid var(--yk-yellow);
  outline-offset: -2px;
}

.page-about .about-milestones__panel {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(12px, 2.4vw, 32px);
  padding-top: clamp(24px, 3.6vw, 40px);
}

.page-about .about-milestones__year-big {
  font-family: var(--yk-cond);
  font-size: clamp(48px, 7.5vw, 96px);
  font-weight: 700;
  line-height: .85;
  letter-spacing: -.01em;
  color: var(--yk-red);
  font-variant-numeric: tabular-nums;
}

.page-about .about-milestones__body h3 {
  font-family: var(--yk-serif);
  font-size: clamp(20px, 2.6vw, 28px);
  font-weight: 700;
  color: var(--yk-white);
  margin-bottom: 12px;
}

.page-about .about-milestones__body p {
  max-width: 66ch;
  color: rgba(244, 247, 251, .8);
}

.page-about .about-timeline__media {
  margin: clamp(36px, 6vw, 72px) 0 0;
}

.page-about .about-timeline__media .yk-media__frame {
  aspect-ratio: 21 / 8;
  min-height: 190px;
  max-height: 460px;
  overflow: hidden;
  border-top: 1px solid var(--yk-line);
  border-bottom: 1px solid var(--yk-line);
}

.page-about .about-timeline__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(.7) contrast(1.1) brightness(.85);
}

.page-about .about-timeline__media .yk-media__caption {
  padding: 12px clamp(18px, 4vw, 56px) 0;
  color: var(--yk-mist);
}

/* ---------- 编年方法 ---------- */
.page-about .about-method {
  list-style: none;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: clamp(24px, 3.4vw, 40px) 0 0;
  padding: 0;
  background: var(--yk-line-soft);
  border: 1px solid var(--yk-line-soft);
}

.page-about .about-method__item {
  background: var(--yk-deep);
  padding: clamp(18px, 2.4vw, 26px);
  border-left: 2px solid transparent;
  transition: background .3s var(--yk-ease), border-color .3s var(--yk-ease);
}

.page-about .about-method__item:hover {
  background: var(--yk-ink);
  border-left-color: var(--yk-red);
}

.page-about .about-method__item h3 {
  font-family: var(--yk-sans);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: .02em;
  color: var(--yk-white);
  margin-bottom: 10px;
}

.page-about .about-method__item p {
  font-size: 15px;
  line-height: 1.7;
  color: var(--yk-mist);
}

/* ---------- 团队 ---------- */
.page-about .about-team__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(26px, 4vw, 56px);
}

.page-about .about-team {
  list-style: none;
  margin: clamp(22px, 3vw, 34px) 0 0;
  padding: 0;
  border-top: 1px solid var(--yk-line);
}

.page-about .about-team__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: clamp(14px, 2.2vw, 28px);
  align-items: start;
  padding: clamp(16px, 2.2vw, 22px) 0;
  border-bottom: 1px solid var(--yk-line);
}

.page-about .about-team__count {
  font-family: var(--yk-cond);
  font-size: clamp(30px, 3.6vw, 44px);
  font-weight: 700;
  line-height: 1;
  color: var(--yk-yellow);
  font-variant-numeric: tabular-nums;
  min-width: 2ch;
}

.page-about .about-team__item h3 {
  font-family: var(--yk-sans);
  font-size: 16px;
  font-weight: 700;
  color: var(--yk-white);
  margin-bottom: 8px;
}

.page-about .about-team__item p {
  font-size: 15px;
  line-height: 1.72;
  color: var(--yk-mist);
}

.page-about .about-team__note {
  margin-top: clamp(20px, 2.8vw, 28px);
  padding: 16px 18px;
  border-left: 2px solid var(--yk-teal);
  background: rgba(42, 157, 143, .08);
  font-size: 15px;
  color: rgba(244, 247, 251, .86);
}

.page-about .about-team__figure .yk-media__frame {
  border: 1px solid var(--yk-line);
  aspect-ratio: 4 / 3;
  overflow: hidden;
}

.page-about .about-team__figure img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(.75) contrast(1.08) brightness(.9);
}

/* ---------- 协作生态 ---------- */
.page-about .about-eco {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin-top: clamp(24px, 3.4vw, 38px);
  background: var(--yk-line-soft);
  border: 1px solid var(--yk-line-soft);
}

.page-about .about-eco__card {
  background: var(--yk-deep);
  padding: clamp(20px, 2.6vw, 30px);
  border-top: 2px solid transparent;
  transition: background .32s var(--yk-ease), border-color .32s var(--yk-ease), transform .32s var(--yk-ease);
}

.page-about .about-eco__card:hover {
  background: var(--yk-ink);
  border-top-color: var(--yk-teal);
}

.page-about .about-eco__metric {
  font-family: var(--yk-mono);
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--yk-teal);
  margin-bottom: 12px;
}

.page-about .about-eco__card h3 {
  font-family: var(--yk-serif);
  font-size: clamp(19px, 2.2vw, 24px);
  font-weight: 700;
  color: var(--yk-white);
  margin-bottom: 10px;
}

.page-about .about-eco__card p:last-child {
  font-size: 15px;
  line-height: 1.72;
  color: var(--yk-mist);
}

.page-about .about-eco__card--gold {
  border-top-color: var(--yk-gold);
  background: linear-gradient(180deg, rgba(233, 196, 106, .09) 0%, var(--yk-deep) 70%);
}

.page-about .about-eco__card--gold:hover {
  border-top-color: var(--yk-gold);
  background: linear-gradient(180deg, rgba(233, 196, 106, .14) 0%, var(--yk-ink) 70%);
}

.page-about .about-eco__card--gold .about-eco__metric {
  color: var(--yk-gold);
}

/* ---------- 未来计划 ---------- */
.page-about .about-plan__list {
  list-style: none;
  margin: clamp(20px, 3vw, 32px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(16px, 2.4vw, 26px);
}

.page-about .about-plan__list li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: clamp(14px, 2vw, 24px);
  align-items: start;
}

.page-about .about-plan__idx {
  font-family: var(--yk-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--yk-night);
  background: var(--yk-gold);
  padding: 5px 9px;
  line-height: 1;
  margin-top: 4px;
}

.page-about .about-plan__list h3 {
  font-family: var(--yk-sans);
  font-size: 16px;
  font-weight: 700;
  color: var(--yk-white);
  margin-bottom: 8px;
}

.page-about .about-plan__list p {
  font-size: 15px;
  line-height: 1.72;
  color: var(--yk-mist);
}

.page-about .about-plan__note {
  margin-top: clamp(20px, 2.8vw, 28px);
  font-family: var(--yk-mono);
  font-size: 13px;
  letter-spacing: .04em;
  color: var(--yk-mist);
}

/* ---------- 延伸入口 ---------- */
.page-about .about-next {
  margin-top: clamp(36px, 6vw, 72px);
  padding-top: clamp(36px, 5vw, 60px);
  border-top: 1px solid var(--yk-line);
}

.page-about .about-next__list {
  list-style: none;
  margin: clamp(22px, 3vw, 34px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--yk-line-soft);
  border: 1px solid var(--yk-line-soft);
}

.page-about .about-next__list li {
  background: var(--yk-deep);
}

.page-about .about-next__list a {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-rows: auto auto;
  column-gap: clamp(14px, 2vw, 22px);
  row-gap: 6px;
  padding: clamp(18px, 2.4vw, 26px);
  color: inherit;
  text-decoration: none;
  transition: background .3s var(--yk-ease);
}

.page-about .about-next__list a:hover,
.page-about .about-next__list a:focus-visible {
  background: var(--yk-ink);
}

.page-about .about-next__idx {
  grid-row: 1 / span 2;
  font-family: var(--yk-cond);
  font-size: clamp(28px, 3.6vw, 42px);
  font-weight: 700;
  line-height: 1;
  color: rgba(244, 247, 251, .16);
}

.page-about .about-next__label {
  font-family: var(--yk-sans);
  font-size: 16px;
  font-weight: 700;
  color: var(--yk-white);
}

.page-about .about-next__desc {
  font-size: 14px;
  line-height: 1.68;
  color: var(--yk-mist);
}

.page-about .about-next__legal {
  margin-top: clamp(20px, 3vw, 28px);
  font-size: 14px;
  color: var(--yk-mist);
}

.page-about .about-next__legal a {
  color: var(--yk-white);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-next__legal a:hover {
  color: var(--yk-yellow);
}

/* ---------- 响应式 ---------- */
@media (min-width: 700px) {
  .page-about .about-hero__stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .page-about .about-milestones__panel {
    grid-template-columns: minmax(120px, 220px) minmax(0, 1fr);
    align-items: start;
  }

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

@media (min-width: 900px) {
  .page-about .yk-chapter {
    grid-template-columns: minmax(84px, 132px) minmax(0, 1fr);
    gap: var(--about-gap);
  }

  .page-about .yk-chapter__num {
    position: sticky;
    top: var(--about-sticky-top);
    align-self: start;
  }

  .page-about .about-eco {
    grid-template-columns: repeat(12, minmax(0, 1fr));
  }

  .page-about .about-eco__card--a { grid-column: span 5; }
  .page-about .about-eco__card--b { grid-column: span 4; }
  .page-about .about-eco__card--c { grid-column: span 3; }
  .page-about .about-eco__card--d { grid-column: span 7; }
  .page-about .about-eco__card--e { grid-column: span 5; }

  .page-about .about-plan__list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: clamp(20px, 2.6vw, 34px) clamp(24px, 4vw, 56px);
  }
}

@media (min-width: 1080px) {
  .page-about .about-method {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-origin__grid {
    grid-template-columns: minmax(0, 1.3fr) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-team__grid {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, .85fr);
    align-items: start;
  }
}

@media (max-width: 460px) {
  .page-about .about-milestones__tab {
    padding: 12px 14px;
    font-size: 12px;
  }

  .page-about .about-team__item,
  .page-about .about-plan__list li {
    grid-template-columns: minmax(0, 1fr);
    gap: 8px;
  }

  .page-about .about-team__count {
    font-size: 26px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-method__item,
  .page-about .about-eco__card,
  .page-about .about-next__list a,
  .page-about .about-milestones__tab {
    transition: none;
  }
}