.page-about {
  --about-ink-soft: #4b544f;
  --about-rule: rgba(224, 169, 74, .32);
  --about-tl-col: 56px;
}

/* ============ 首屏 ============ */
.page-about .about-hero {
  padding-block: clamp(20px, 3.5vw, 40px) clamp(60px, 9vw, 116px);
  background:
    radial-gradient(120% 92% at 86% -4%, #16362c 0%, rgba(11, 15, 14, 0) 62%),
    linear-gradient(180deg, var(--obsidian) 0%, #0d1613 100%);
}

.page-about .about-hero .breadcrumb {
  margin-bottom: clamp(28px, 5vw, 56px);
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(32px, 5vw, 56px);
}

.page-about .about-hero__title {
  margin: 14px 0 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(32px, 5.6vw, 66px);
  line-height: 1.14;
  letter-spacing: -.02em;
  color: var(--white);
  max-width: 14em;
}

.page-about .about-hero__lead {
  margin: 22px 0 0;
  font-size: clamp(16px, 1.6vw, 18px);
  line-height: 1.75;
  color: rgba(251, 247, 239, .82);
  max-width: 34em;
}

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

.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin: clamp(36px, 5vw, 56px) 0 0;
  padding-top: 22px;
  border-top: 1px solid var(--about-rule);
}

.page-about .about-stat__label {
  margin: 0;
  font-size: 13px;
  letter-spacing: .04em;
  color: var(--mist);
}

.page-about .about-stat__num {
  margin: 6px 0 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(28px, 3.6vw, 40px);
  line-height: 1;
  color: var(--amber);
}

.page-about .about-hero__media .media__frame {
  aspect-ratio: 3 / 2;
}

/* ============ 时间轴 ============ */
.page-about .about-origin {
  padding-block: clamp(56px, 8vw, 108px);
  background: linear-gradient(180deg, #0d1613 0%, var(--felt) 18%, #10261f 100%);
}

.page-about .timeline {
  list-style: none;
  margin: clamp(36px, 5vw, 64px) 0 0;
  padding: 0;
}

.page-about .timeline__item {
  position: relative;
  display: grid;
  grid-template-columns: var(--about-tl-col) minmax(0, 1fr);
  gap: clamp(16px, 3vw, 40px);
  padding-block: clamp(24px, 3.5vw, 40px);
}

.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: 20px;
  top: 0;
  bottom: 0;
  width: 1px;
  background: linear-gradient(180deg, rgba(224, 169, 74, 0) 0%, rgba(224, 169, 74, .45) 18%, rgba(224, 169, 74, .45) 82%, rgba(224, 169, 74, 0) 100%);
}

.page-about .timeline__item:first-child::before {
  top: 50%;
}

.page-about .timeline__num {
  position: relative;
  z-index: 1;
  align-self: start;
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 14px;
  color: var(--amber);
  background: var(--felt);
  border: 1px solid var(--amber-dim);
  clip-path: polygon(0 0, calc(100% - 10px) 0, 100% 10px, 100% 100%, 10px 100%, 0 calc(100% - 10px));
}

.page-about .timeline__title {
  margin: 6px 0 0;
  font-family: var(--font-cond);
  font-weight: 700;
  font-size: clamp(19px, 2.2vw, 24px);
  line-height: 1.4;
  color: var(--white);
}

.page-about .timeline__text {
  margin: 12px 0 0;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(251, 247, 239, .74);
  max-width: 40em;
}

/* ============ 五条常设线 ============ */
.page-about .about-lines {
  padding-block: clamp(56px, 8vw, 108px);
  background: linear-gradient(180deg, #10261f 0%, var(--obsidian) 100%);
}

.page-about .lines {
  margin-top: clamp(32px, 4vw, 56px);
  border-top: 1px solid rgba(31, 94, 78, .6);
}

.page-about .lines__item {
  border-bottom: 1px solid rgba(31, 94, 78, .6);
}

.page-about .lines__head {
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr) 24px;
  align-items: center;
  gap: 12px;
  width: 100%;
  padding: clamp(18px, 2.4vw, 24px) 4px;
  text-align: left;
  background: transparent;
  border: 0;
  color: var(--white);
  cursor: pointer;
  transition: color .18s var(--ease);
}

.page-about .lines__head:hover {
  color: var(--amber);
}

.page-about .lines__index {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 13px;
  color: var(--amber-dim);
}

.page-about .lines__name {
  font-family: var(--font-cond);
  font-weight: 700;
  font-size: clamp(18px, 2.2vw, 23px);
  letter-spacing: .01em;
}

.page-about .lines__item .expand__icon {
  justify-self: end;
  position: relative;
  width: 16px;
  height: 16px;
}

.page-about .lines__item .expand__icon::before,
.page-about .lines__item .expand__icon::after {
  content: "";
  position: absolute;
  left: 0;
  top: 7px;
  width: 16px;
  height: 1px;
  background: currentColor;
  transition: transform .22s var(--ease), opacity .22s var(--ease);
}

.page-about .lines__item .expand__icon::after {
  transform: rotate(90deg);
}

.page-about .lines__item[data-open] .expand__icon::after {
  transform: rotate(0deg);
  opacity: 0;
}

.page-about .lines__item .expand__body {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows .3s var(--ease);
}

.page-about .lines__item[data-open] .expand__body {
  grid-template-rows: 1fr;
}

.page-about .lines__item .expand__inner {
  overflow: hidden;
}

.page-about .lines__text {
  margin: 0 0 clamp(20px, 2.6vw, 28px);
  padding-left: 58px;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(251, 247, 239, .74);
  max-width: 44em;
}

/* ============ 段位阶梯 ============ */
.page-about .about-tiers {
  padding-block: clamp(56px, 8vw, 108px);
  color: var(--ink);
}

.page-about .about-tiers .eyebrow {
  color: var(--amber-dim);
}

.page-about .about-tiers .section-head__title,
.page-about .about-tiers .section-head__lead {
  color: var(--ink);
}

.page-about .about-tiers .section-head__lead {
  opacity: .78;
}

.page-about .about-tiers__top {
  display: grid;
  gap: clamp(28px, 4vw, 48px);
}

.page-about .about-tiers__media .media__frame {
  aspect-ratio: 1 / 1;
}

.page-about .tiers {
  list-style: none;
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: 62%;
  gap: 10px;
  margin: clamp(36px, 5vw, 60px) 0 0;
  padding: 0 0 8px;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch;
}

.page-about .tier {
  scroll-snap-align: start;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: 6px;
  min-height: 148px;
  padding: 20px 16px;
  background: linear-gradient(180deg, #1f5e4e 0%, #17453a 60%, #10261f 100%);
  border: 1px solid var(--felt-line);
  color: var(--white);
  clip-path: polygon(0 0, calc(100% - 14px) 0, 100% 14px, 100% 100%, 14px 100%, 0 calc(100% - 14px));
  transition: transform .16s var(--ease), border-color .16s var(--ease), box-shadow .16s var(--ease);
}

.page-about .tier:hover {
  transform: translateY(-6px);
  border-color: var(--amber);
  box-shadow: 0 12px 26px rgba(11, 15, 14, .28);
}

.page-about .tier__roman {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--amber);
}

.page-about .tier__name {
  font-family: var(--font-cond);
  font-weight: 700;
  font-size: clamp(19px, 2.4vw, 22px);
  letter-spacing: .04em;
}

.page-about .tier__meta {
  font-size: 13px;
  color: rgba(251, 247, 239, .62);
}

.page-about .about-tiers__notes {
  display: grid;
  gap: 14px;
  margin-top: clamp(28px, 4vw, 44px);
  padding-top: 24px;
  border-top: 1px dashed rgba(168, 122, 44, .55);
}

.page-about .about-tiers__note {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--about-ink-soft);
}

.page-about .about-tiers__note strong {
  display: inline-block;
  min-width: 5.5em;
  margin-right: 10px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .06em;
  color: var(--amber-dim);
}

/* ============ 两端分工 ============ */
.page-about .about-split {
  padding-block: clamp(56px, 8vw, 108px);
  background: linear-gradient(160deg, #0d1613 0%, var(--obsidian) 55%, #13221d 100%);
}

.page-about .split {
  display: grid;
  gap: clamp(28px, 4vw, 52px);
  margin-top: clamp(32px, 4vw, 52px);
}

.page-about .split__media .media__frame {
  aspect-ratio: 4 / 3;
}

.page-about .split__cols {
  display: grid;
  gap: 24px;
}

.page-about .split__col {
  padding: 24px 22px;
  background: linear-gradient(180deg, rgba(23, 69, 58, .55), rgba(16, 38, 31, .55));
  border-left: 2px solid var(--amber-dim);
}

.page-about .split__title {
  margin: 0;
  font-family: var(--font-cond);
  font-weight: 700;
  font-size: clamp(18px, 2.1vw, 21px);
  color: var(--white);
}

.page-about .split__text {
  margin: 12px 0 0;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(251, 247, 239, .74);
}

/* ============ 更新节奏 ============ */
.page-about .about-cadence {
  padding-block: clamp(56px, 8vw, 108px);
  background: linear-gradient(180deg, #13221d 0%, var(--felt) 100%);
}

.page-about .cadence {
  list-style: none;
  display: grid;
  gap: 18px;
  margin: clamp(32px, 4vw, 52px) 0 0;
  padding: 0;
}

.page-about .cadence__item {
  padding: 20px 20px 22px;
  background: rgba(11, 15, 14, .42);
  border: 1px solid rgba(31, 94, 78, .7);
  clip-path: polygon(0 0, calc(100% - 14px) 0, 100% 14px, 100% 100%, 14px 100%, 0 calc(100% - 14px));
}

.page-about .cadence__text {
  margin: 14px 0 0;
  font-size: 15.5px;
  line-height: 1.78;
  color: rgba(251, 247, 239, .76);
}

.page-about .cadence__more {
  margin: clamp(28px, 4vw, 40px) 0 0;
  font-size: 15px;
  color: rgba(251, 247, 239, .74);
}

.page-about .cadence__link {
  color: var(--amber);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .cadence__link:hover {
  color: var(--white);
}

/* ============ 备案与基本情况 ============ */
.page-about .about-facts {
  padding-block: clamp(56px, 8vw, 104px);
  background: linear-gradient(180deg, var(--paper) 0%, #e8dfcd 100%);
  color: var(--ink);
}

.page-about .about-facts .eyebrow {
  color: var(--amber-dim);
}

.page-about .about-facts .section-head__title,
.page-about .about-facts .section-head__lead {
  color: var(--ink);
}

.page-about .about-facts .section-head__lead {
  opacity: .78;
}

.page-about .facts {
  margin: clamp(30px, 4vw, 44px) 0 0;
  border-top: 1px solid rgba(16, 38, 31, .18);
}

.page-about .facts__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: baseline;
  gap: 16px;
  padding: 16px 2px;
  border-bottom: 1px solid rgba(16, 38, 31, .14);
}

.page-about .facts__key {
  margin: 0;
  font-size: 15px;
  color: var(--about-ink-soft);
}

.page-about .facts__val {
  margin: 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 15px;
  letter-spacing: .02em;
  color: var(--ink);
  text-align: right;
}

.page-about .facts__note {
  margin: 26px 0 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--about-ink-soft);
}

.page-about .facts__link {
  color: var(--amber-dim);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .facts__link:hover {
  color: var(--ink);
}

/* ============ 响应式 ============ */
@media (min-width: 760px) {
  .page-about .tiers {
    grid-auto-flow: row;
    grid-template-columns: repeat(6, minmax(0, 1fr));
    grid-auto-columns: auto;
    gap: 12px;
    overflow: visible;
    scroll-snap-type: none;
    padding-bottom: 0;
    align-items: end;
  }

  .page-about .tier:nth-child(1) { min-height: 132px; }
  .page-about .tier:nth-child(2) { min-height: 150px; }
  .page-about .tier:nth-child(3) { min-height: 168px; }
  .page-about .tier:nth-child(4) { min-height: 186px; }
  .page-about .tier:nth-child(5) { min-height: 204px; }
  .page-about .tier:nth-child(6) { min-height: 222px; }

  .page-about .about-tiers__notes {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 22px;
  }

  .page-about .about-tiers__note strong {
    display: block;
    min-width: 0;
    margin: 0 0 6px;
  }

  .page-about .cadence {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 20px;
  }

  .page-about .split__cols {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 22px;
  }
}

@media (min-width: 980px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
    align-items: center;
  }

  .page-about .about-tiers__top {
    grid-template-columns: minmax(0, 1fr) minmax(0, .8fr);
    align-items: center;
    gap: clamp(40px, 5vw, 72px);
  }

  .page-about .split {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, .9fr);
    align-items: start;
  }

  .page-about .split__cols {
    grid-template-columns: minmax(0, 1fr);
    gap: 20px;
  }

  .page-about .lines__head {
    grid-template-columns: 64px minmax(0, 1fr) 28px;
    gap: 20px;
  }

  .page-about .lines__text {
    padding-left: 84px;
  }
}