.page-about {
  --ab-line-soft: rgba(27, 42, 85, .10);
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  padding-bottom: clamp(40px, 7vw, 88px);
}

.page-about .sb-section {
  padding-top: clamp(44px, 7vw, 88px);
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  padding: clamp(20px, 4vw, 40px) 0 clamp(28px, 4vw, 48px);
  border-bottom: 1px solid var(--line-ink);
}

.page-about .ab-hero__title {
  font-family: var(--font-serif);
  font-weight: 900;
  font-size: clamp(1.9rem, 6.4vw, 4.2rem);
  line-height: 1.14;
  letter-spacing: -0.01em;
  color: var(--indigo);
  margin: 14px 0 0;
  max-width: 18em;
}

.page-about .ab-hero__lead {
  margin: clamp(18px, 3vw, 26px) 0 0;
  max-width: 46em;
  color: var(--ink);
}

.page-about .ab-stats {
  list-style: none;
  margin: clamp(26px, 4vw, 44px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line-ink-soft);
  border-top: 1px solid var(--line-ink);
  border-bottom: 1px solid var(--line-ink);
}

.page-about .ab-stats li {
  background: var(--paper);
  padding: 16px 14px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.page-about .ab-stats__num {
  font-family: var(--font-mono);
  font-size: clamp(1.25rem, 3vw, 1.9rem);
  letter-spacing: .01em;
  color: var(--brick);
}

.page-about .ab-stats__label {
  font-size: 13px;
  line-height: 1.5;
  letter-spacing: .02em;
  color: var(--slate);
}

/* ---------- 通用栅格与媒体 ---------- */
.page-about .ab-split {
  display: grid;
  gap: clamp(22px, 3.4vw, 44px);
  align-items: start;
}

.page-about .sb-media__frame {
  overflow: hidden;
  border: 1px solid var(--line-ink-soft);
  border-radius: var(--radius);
  background: var(--card);
}

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

.page-about .sb-media__cap {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--slate);
}

.page-about .sb-h2 {
  font-family: var(--font-serif);
  color: var(--indigo);
  margin: 8px 0 14px;
}

.page-about .sb-text {
  margin: 0 0 1.05em;
  max-width: 34em;
}

.page-about .ab-inline-link {
  color: var(--brick);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}

.page-about .ab-inline-link:hover {
  color: var(--indigo);
}

/* ---------- 起点 ---------- */
.page-about .ab-origin__figure {
  margin: 0;
}

.page-about .ab-callout {
  margin-top: 18px;
  background: var(--brick-soft);
  border-left: 3px solid var(--brick);
}

.page-about .ab-callout p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--indigo);
}

/* ---------- 沿革 ---------- */
.page-about .ab-head {
  max-width: 52em;
}

.page-about .ab-head__lead {
  margin-bottom: 0;
}

.page-about .ab-mile__banner {
  margin: clamp(24px, 4vw, 40px) 0 0;
}

.page-about .ab-mile__body {
  display: grid;
  gap: clamp(18px, 3vw, 34px);
  margin-top: clamp(26px, 4vw, 46px);
}

.page-about .ab-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 6px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .ab-rail__link {
  display: inline-flex;
  align-items: center;
  white-space: nowrap;
  padding: 7px 12px;
  border: 1px solid var(--line-ink-soft);
  border-radius: 2px;
  background: var(--card);
  color: var(--slate);
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: .04em;
  text-decoration: none;
}

.page-about .ab-rail__link:hover {
  border-color: var(--line-gold);
  color: var(--indigo);
}

.page-about .ab-rail__link[aria-current] {
  background: var(--indigo);
  border-color: var(--indigo);
  color: #fff;
}

.page-about .ab-node {
  position: relative;
  padding: 0 0 clamp(24px, 3vw, 34px) 20px;
  border-left: 1px solid var(--line-ink);
}

.page-about .ab-node::before {
  content: "";
  position: absolute;
  left: -4.5px;
  top: 14px;
  width: 8px;
  height: 8px;
  background: var(--card);
  border: 1px solid var(--copper);
  border-radius: 1px;
}

.page-about .ab-node:last-of-type {
  padding-bottom: 6px;
  border-left-color: transparent;
}

.page-about .ab-node:last-of-type::before {
  display: none;
}

.page-about .ab-node__year {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.8rem, 4.4vw, 4rem);
  line-height: 1;
  letter-spacing: .01em;
  color: var(--indigo);
}

.page-about .ab-node[aria-current] .ab-node__year {
  color: var(--brick);
}

.page-about .ab-node .sb-h3 {
  font-family: var(--font-serif);
  font-size: clamp(1.1rem, 2.2vw, 1.45rem);
  color: var(--indigo);
  margin: 8px 0 10px;
}

.page-about .ab-node .sb-text {
  max-width: 36em;
  margin-bottom: 10px;
}

.page-about .ab-node__more {
  margin: 0;
  padding-left: 12px;
  border-left: 2px solid var(--line-gold);
  max-width: 34em;
  font-size: 14px;
  line-height: 1.7;
  color: var(--slate);
}

.page-about .ab-mile__more {
  margin: 22px 0 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--slate);
}

/* ---------- 收录方法 ---------- */
.page-about .ab-scheme__intro .sb-note {
  display: block;
  margin-top: 6px;
  color: var(--slate);
}

.page-about .ab-code {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.page-about .ab-code__item {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 14px 12px;
  background: var(--card);
  border: 1px solid var(--line-ink-soft);
  border-top: 3px solid var(--copper);
  border-radius: 2px;
}

.page-about .ab-code__idx {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--copper);
}

.page-about .ab-code__name {
  font-family: var(--font-serif);
  font-size: 18px;
  color: var(--indigo);
}

.page-about .ab-code__desc {
  font-size: 13px;
  line-height: 1.65;
  color: var(--slate);
}

.page-about .ab-scheme__figure {
  margin: clamp(26px, 4vw, 46px) auto 0;
  max-width: 660px;
}

.page-about .ab-cats {
  margin-top: clamp(26px, 4vw, 44px);
  border-top: 1px solid var(--line-ink);
}

.page-about .ab-cat {
  border-bottom: 1px solid var(--line-ink-soft);
}

.page-about .ab-cat .sb-row__head {
  margin: 0;
  font-size: inherit;
  font-weight: inherit;
}

.page-about .ab-cat__toggle {
  display: flex;
  align-items: baseline;
  gap: clamp(10px, 2vw, 22px);
  width: 100%;
  padding: 16px 2px;
  background: none;
  border: 0;
  cursor: pointer;
  text-align: left;
  font-family: inherit;
  color: var(--indigo);
}

.page-about .ab-cat__toggle:hover .sb-row__title {
  color: var(--brick);
}

.page-about .ab-cat__toggle .sb-row__num {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--copper);
}

.page-about .ab-cat__toggle .sb-row__title {
  font-family: var(--font-serif);
  font-size: clamp(1.02rem, 2vw, 1.28rem);
  transition: color .18s ease;
}

.page-about .ab-cat__side {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .04em;
  color: var(--slate);
  text-align: right;
}

.page-about .ab-cat__toggle[aria-expanded="true"] {
  color: var(--brick);
}

.page-about .ab-cat .sb-row__inner {
  padding: 0 2px 18px;
  max-width: 44em;
}

.page-about .ab-cat .sb-row__inner .sb-text {
  font-size: 15px;
}

/* ---------- 团队 ---------- */
.page-about .ab-team__roles {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .ab-role {
  padding: 16px;
  background: var(--card);
  border: 1px solid var(--line-ink-soft);
  border-left: 3px solid var(--indigo);
  border-radius: 2px;
}

.page-about .ab-role__num {
  display: block;
  font-family: var(--font-mono);
  font-size: 28px;
  line-height: 1;
  color: var(--brick);
}

.page-about .ab-role__title {
  font-family: var(--font-serif);
  font-size: 16px;
  color: var(--indigo);
  margin: 8px 0 8px;
}

.page-about .ab-role p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--slate);
}

.page-about .ab-team__note {
  margin-top: 12px;
  padding: 16px;
  background: var(--mist);
  border-radius: 2px;
}

.page-about .ab-team__note p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--indigo);
}

/* ---------- 合作品牌 ---------- */
.page-about .ab-eco__bar {
  display: flex;
  flex-direction: column;
  margin-top: clamp(22px, 3vw, 34px);
  border: 1px solid var(--line-ink-soft);
  border-radius: 2px;
  overflow: hidden;
}

.page-about .ab-eco__seg {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  padding: 16px 14px;
  transition: filter .2s ease;
}

.page-about .ab-eco__seg--a {
  background: var(--indigo);
  color: #fff;
}

.page-about .ab-eco__seg--b {
  background: var(--brick-soft);
  color: var(--indigo);
}

.page-about .ab-eco__seg:hover {
  filter: brightness(1.08);
}

.page-about .ab-eco__pct {
  font-family: var(--font-mono);
  font-size: 18px;
  letter-spacing: .02em;
}

.page-about .ab-eco__names {
  font-size: 12.5px;
  line-height: 1.5;
  letter-spacing: .02em;
}

.page-about .ab-eco__notes {
  display: grid;
  gap: 12px;
  margin-top: 16px;
}

.page-about .ab-note-card {
  padding: 18px;
  background: var(--card);
  border: 1px solid var(--line-ink-soft);
  border-top: 3px solid var(--copper);
  border-radius: 2px;
}

.page-about .ab-note-card__title {
  font-family: var(--font-serif);
  font-size: 16px;
  color: var(--indigo);
  margin: 0 0 8px;
}

.page-about .ab-note-card p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--slate);
}

/* ---------- 往后 ---------- */
.page-about .ab-future__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .ab-future__list li {
  display: flex;
  gap: 14px;
  padding: 14px 16px;
  background: var(--card);
  border-left: 3px solid var(--copper);
  border-radius: 2px;
}

.page-about .ab-future__num {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--copper);
  padding-top: 4px;
}

.page-about .ab-future__list p {
  margin: 0;
  font-size: 15px;
  line-height: 1.72;
  color: var(--ink);
}

.page-about .ab-cta {
  margin-top: clamp(30px, 5vw, 56px);
}

/* ---------- 桌面栅格与交互 ---------- */
@media (min-width: 700px) {
  .page-about .ab-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .page-about .ab-team__roles {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .ab-eco__bar {
    flex-direction: row;
    height: 68px;
  }

  .page-about .ab-eco__seg {
    padding: 0 18px;
  }

  .page-about .ab-eco__seg--a {
    width: 54%;
  }

  .page-about .ab-eco__seg--b {
    width: 46%;
  }

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

@media (min-width: 900px) {
  .page-about .ab-split--7-5 {
    grid-template-columns: 7fr 5fr;
  }

  .page-about .ab-split--5-7 {
    grid-template-columns: 5fr 7fr;
  }

  .page-about .ab-split--4-8 {
    grid-template-columns: 4fr 8fr;
  }

  .page-about .ab-mile__body {
    grid-template-columns: minmax(118px, 172px) minmax(0, 1fr);
    gap: clamp(30px, 5vw, 68px);
  }

  .page-about .ab-rail {
    position: sticky;
    top: 112px;
    align-self: start;
  }

  .page-about .ab-rail__list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    padding-bottom: 0;
    border-left: 1px solid var(--line-gold);
  }

  .page-about .ab-rail__link {
    position: relative;
    justify-content: flex-start;
    width: 100%;
    padding: 11px 14px;
    background: transparent;
    border: 0;
    border-radius: 0;
  }

  .page-about .ab-rail__link::before {
    content: "";
    position: absolute;
    left: -5px;
    top: 50%;
    transform: translateY(-50%);
    width: 9px;
    height: 9px;
    background: var(--paper);
    border: 1px solid var(--copper);
    border-radius: 1px;
  }

  .page-about .ab-rail__link[aria-current] {
    background: var(--brick-soft);
    color: var(--brick);
  }

  .page-about .ab-rail__link[aria-current]::before {
    background: var(--brick);
    border-color: var(--brick);
  }
}

@media (hover: hover) {
  .page-about .ab-node__more {
    opacity: .6;
    transform: translateY(3px);
    transition: opacity .22s ease, transform .22s ease, border-left-color .22s ease;
    border-left-color: var(--line-ink-soft);
  }

  .page-about .ab-node:hover .ab-node__more,
  .page-about .ab-node:focus-within .ab-node__more {
    opacity: 1;
    transform: translateY(0);
    border-left-color: var(--copper);
  }
}