.page-about {
  --ab-line: rgba(11, 79, 158, 0.14);
  --ab-line-soft: rgba(11, 79, 158, 0.08);
  --ab-aside-w: 190px;
  --ab-shadow-soft: 0 18px 40px -26px rgba(6, 51, 95, 0.5);
  background: var(--ht-snow);
  color: var(--ht-ink);
  overflow-x: hidden;
}

.page-about .ab-link {
  color: var(--ht-blue);
  text-decoration: none;
  border-bottom: 1px solid var(--ht-line-strong);
  padding-bottom: 1px;
  transition: color 0.2s ease, border-color 0.2s ease;
}

.page-about .ab-link:hover,
.page-about .ab-link:focus-visible {
  color: var(--ht-red);
  border-bottom-color: var(--ht-orange);
}

.page-about .ab-link:focus-visible {
  outline: 2px solid var(--ht-orange);
  outline-offset: 3px;
}

/* ============ HERO ============ */
.page-about .ab-hero {
  position: relative;
  overflow: hidden;
  padding: 22px 0 46px;
  background: linear-gradient(178deg, #e7f0fa 0%, #f2f7fc 42%, var(--ht-snow) 100%);
}

.page-about .ab-hero__slant {
  display: none;
}

.page-about .ab-hero__grid {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 28px;
}

.page-about .ab-hero__copy {
  min-width: 0;
}

.page-about .ab-hero__copy .ht-eyebrow {
  margin: 18px 0 12px;
  color: var(--ht-blue);
}

.page-about .ab-hero__copy .ht-title--xl,
.page-about .ab-hero__copy h1 {
  font-family: var(--ht-font-head);
  font-weight: 900;
  font-size: clamp(30px, 7.2vw, 56px);
  line-height: 1.14;
  letter-spacing: -0.02em;
  margin: 0 0 18px;
  color: var(--ht-ink);
  max-width: 18em;
}

.page-about .ab-hero__copy h1::after {
  content: "";
  display: block;
  width: 68px;
  height: 6px;
  margin-top: 20px;
  background: linear-gradient(90deg, var(--ht-red) 0 62%, var(--ht-gold) 62% 100%);
}

.page-about .ab-hero__copy .ht-lede {
  font-size: 16px;
  line-height: 1.8;
  color: #3d4c60;
  max-width: 46ch;
  margin: 0 0 22px;
}

.page-about .ab-hero__badges {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .ab-hero__figure {
  position: relative;
  margin: 0;
  min-width: 0;
}

.page-about .ab-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  aspect-ratio: 14 / 9;
  object-fit: cover;
  background: var(--ht-blue-deep);
}

.page-about .ab-hero__figure .ht-media__tag {
  position: absolute;
  left: 0;
  bottom: 0;
  display: inline-block;
  padding: 7px 14px;
  background: var(--ht-blue-deep);
  color: var(--ht-snow);
  font-family: var(--ht-font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
}

/* ============ 阶段索引条 ============ */
.page-about .ab-index {
  position: relative;
  border-top: 1px solid var(--ab-line);
  border-bottom: 1px solid var(--ab-line);
  background:
    linear-gradient(90deg, rgba(111, 179, 224, 0.14) 0%, rgba(247, 249, 252, 0.6) 34%, rgba(247, 249, 252, 0.6) 100%);
}

.page-about .ab-index__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 22px;
  padding: 14px 0;
}

.page-about .ab-index__label {
  font-family: var(--ht-font-mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.16em;
  color: var(--ht-mist);
  padding-right: 6px;
  border-right: 1px solid var(--ab-line);
}

.page-about .ab-index__list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 20px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .ab-index__link {
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  padding-bottom: 2px;
  font-size: 14px;
  color: var(--ht-ink);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease;
}

.page-about .ab-index__link:hover,
.page-about .ab-index__link:focus-visible {
  color: var(--ht-blue);
  border-bottom-color: var(--ht-orange);
}

.page-about .ab-index__link:focus-visible {
  outline: 2px solid var(--ht-orange);
  outline-offset: 3px;
}

.page-about .ab-index__no {
  font-family: var(--ht-font-mono);
  font-size: 11px;
  font-weight: 700;
  color: var(--ht-red);
}

/* ============ 章节骨架 ============ */
.page-about .ab-chapter {
  position: relative;
}

.page-about .ab-chapter__grid {
  display: grid;
  gap: 22px;
}

.page-about .ab-chapter__aside {
  position: relative;
  padding-left: 14px;
  border-left: 3px solid var(--ht-red);
}

.page-about .ab-chapter__no {
  font-family: var(--ht-font-mono);
  font-size: 38px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.04em;
  margin: 0 0 8px;
  color: var(--ht-blue);
  opacity: 0.24;
}

.page-about .ab-chapter__tag {
  font-family: var(--ht-font-head);
  font-weight: 800;
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--ht-red);
  margin: 0 0 12px;
}

.page-about .ab-chapter__aside .ht-note {
  margin: 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--ht-mist);
  max-width: 30ch;
}

.page-about .ab-chapter__body {
  min-width: 0;
}

.page-about .ab-chapter__body h2 {
  margin: 0 0 18px;
  font-size: clamp(24px, 4.4vw, 34px);
  line-height: 1.28;
  color: var(--ht-ink);
}

.page-about .ab-chapter__body p {
  margin: 0 0 18px;
  font-size: 16px;
  line-height: 1.85;
  color: #334155;
  max-width: 64ch;
}

.page-about .ab-chapter__figure {
  position: relative;
  margin: 8px 0 24px;
  min-width: 0;
}

.page-about .ab-chapter__figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  background: var(--ht-blue-deep);
}

.page-about .ab-chapter__figure figcaption {
  position: absolute;
  left: 0;
  bottom: 0;
  display: inline-block;
  padding: 6px 13px;
  background: rgba(6, 51, 95, 0.9);
  color: var(--ht-snow);
  font-family: var(--ht-font-mono);
  font-size: 11px;
  letter-spacing: 0.05em;
}

.page-about .ab-chapter__figure--wide img {
  aspect-ratio: 16 / 9;
}

/* ============ 青训手风琴 ============ */
.page-about .ab-fold {
  margin: 4px 0 26px;
  border-top: 1px solid var(--ab-line);
}

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

.page-about .ab-fold__item .ht-disclosure__trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  width: 100%;
  padding: 15px 2px;
  background: transparent;
  border: 0;
  text-align: left;
  cursor: pointer;
  color: var(--ht-ink);
  transition: color 0.2s ease, background 0.2s ease;
}

.page-about .ab-fold__item .ht-disclosure__trigger:hover,
.page-about .ab-fold__item .ht-disclosure__trigger:focus-visible {
  color: var(--ht-blue);
  background: linear-gradient(90deg, rgba(111, 179, 224, 0.14), rgba(111, 179, 224, 0));
}

.page-about .ab-fold__item .ht-disclosure__trigger:focus-visible {
  outline: 2px solid var(--ht-orange);
  outline-offset: -2px;
}

.page-about .ab-fold__label {
  font-family: var(--ht-font-head);
  font-weight: 800;
  font-size: 15px;
  letter-spacing: 0.01em;
}

.page-about .ab-fold__item .ht-disclosure__panel {
  padding: 0 2px 16px;
}

.page-about .ab-fold__item .ht-disclosure__body p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: #4a5a6e;
  max-width: 62ch;
}

.page-about .ab-fold__item[data-open] .ht-disclosure__panel,
.page-about .ab-fold__item.is-on .ht-disclosure__panel {
  display: block;
}

/* ============ 数据条 ============ */
.page-about .ab-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(132px, 1fr));
  gap: 0;
  list-style: none;
  margin: 10px 0 26px;
  padding: 0;
  border-top: 1px solid var(--ht-line-strong);
  border-left: 1px solid var(--ab-line);
}

.page-about .ab-stats__item {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 18px 16px 20px;
  border-right: 1px solid var(--ab-line);
  border-bottom: 1px solid var(--ab-line);
  background: linear-gradient(180deg, rgba(111, 179, 224, 0.09), rgba(247, 249, 252, 0));
}

.page-about .ab-stats__item:nth-child(3n + 2) {
  background: linear-gradient(180deg, rgba(232, 163, 61, 0.12), rgba(247, 249, 252, 0));
}

.page-about .ab-stats__item:nth-child(3n) {
  background: linear-gradient(180deg, rgba(46, 125, 91, 0.1), rgba(247, 249, 252, 0));
}

.page-about .ab-stats__num {
  font-family: var(--ht-font-mono);
  font-weight: 700;
  font-size: 30px;
  line-height: 1.05;
  letter-spacing: -0.03em;
  color: var(--ht-blue);
}

.page-about .ab-stats__unit {
  font-family: var(--ht-font-mono);
  font-size: 12px;
  color: var(--ht-red);
  letter-spacing: 0.08em;
}

.page-about .ab-stats__label {
  margin-top: 6px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--ht-mist);
}

.page-about .ab-honor {
  position: relative;
  padding: 20px 20px 20px 26px;
  background: linear-gradient(120deg, rgba(11, 79, 158, 0.07), rgba(232, 163, 61, 0.09));
  border-left: 3px solid var(--ht-gold);
}

.page-about .ab-honor__lead {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: #334155;
  max-width: 62ch;
}

/* ============ 斜向时间轴 ============ */
.page-about .ab-track {
  position: relative;
  list-style: none;
  margin: 14px 0 0;
  padding: 0 0 0 34px;
}

.page-about .ab-track::before {
  content: "";
  position: absolute;
  left: 9px;
  top: 14px;
  bottom: 22px;
  width: 2px;
  background: linear-gradient(180deg,
    var(--ht-blue) 0%,
    var(--ht-sky) 38%,
    var(--ht-gold) 68%,
    var(--ht-red) 100%);
  opacity: 0.7;
}

.page-about .ab-track__item {
  position: relative;
  padding-bottom: 10px;
}

.page-about .ab-track__item::before {
  content: "";
  position: absolute;
  left: -32px;
  top: 16px;
  width: 11px;
  height: 11px;
  background: var(--ht-snow);
  border: 2px solid var(--ht-blue);
  transform: rotate(45deg);
  transition: background 0.2s ease, border-color 0.2s ease;
}

.page-about .ab-track__item:last-child::before {
  border-color: var(--ht-red);
}

.page-about .ab-track__item:hover::before {
  background: var(--ht-orange);
  border-color: var(--ht-orange);
}

.page-about .ab-track__trigger {
  display: grid;
  grid-template-columns: 1fr auto;
  grid-template-areas:
    "season icon"
    "head icon";
  align-items: center;
  gap: 2px 14px;
  width: 100%;
  padding: 12px 14px 14px 0;
  background: transparent;
  border: 0;
  border-bottom: 1px solid var(--ab-line);
  text-align: left;
  cursor: pointer;
  transition: background 0.2s ease, border-color 0.2s ease;
}

.page-about .ab-track__trigger:hover,
.page-about .ab-track__trigger:focus-visible {
  background: linear-gradient(90deg, rgba(232, 163, 61, 0.12), rgba(232, 163, 61, 0));
  border-bottom-color: var(--ht-line-strong);
}

.page-about .ab-track__trigger:focus-visible {
  outline: 2px solid var(--ht-orange);
  outline-offset: -2px;
}

.page-about .ab-track__season {
  grid-area: season;
  font-family: var(--ht-font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.09em;
  color: var(--ht-red);
}

.page-about .ab-track__head {
  grid-area: head;
  font-family: var(--ht-font-serif);
  font-weight: 600;
  font-size: 17px;
  line-height: 1.5;
  color: var(--ht-ink);
}

.page-about .ab-track__trigger .ht-disclosure__icon {
  grid-area: icon;
  align-self: center;
}

.page-about .ab-track__item .ht-disclosure__panel {
  padding-right: 14px;
}

.page-about .ab-track__item .ht-disclosure__body p {
  margin: 12px 0 14px;
  font-size: 14.5px;
  line-height: 1.85;
  color: #4a5a6e;
  max-width: 62ch;
}

/* ============ 收尾 ============ */
.page-about .ab-close {
  padding-bottom: clamp(64px, 11vw, 132px);
}

.page-about .ab-close__panel {
  position: relative;
  overflow: hidden;
  display: grid;
  gap: 22px;
  padding: 34px 24px 34px 30px;
  border-radius: 0;
  background:
    linear-gradient(140deg, var(--ht-blue) 0%, var(--ht-blue-deep) 58%, #052a4d 100%);
  box-shadow: var(--ab-shadow-soft);
}

.page-about .ab-close__flag {
  position: absolute;
  inset: 0 auto 0 0;
  width: 6px;
  background: linear-gradient(180deg,
    var(--ht-red) 0 22%,
    var(--ht-gold) 22% 44%,
    var(--ht-green) 44% 66%,
    var(--ht-sky) 66% 100%);
}

.page-about .ab-close__eyebrow {
  margin: 0 0 10px;
  font-family: var(--ht-font-mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.2em;
  color: var(--ht-gold);
}

.page-about .ab-close__title {
  margin: 0 0 12px;
  font-size: clamp(22px, 4.6vw, 32px);
  line-height: 1.3;
  color: var(--ht-snow);
  max-width: 22em;
}

.page-about .ab-close__desc {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: rgba(247, 249, 252, 0.78);
  max-width: 56ch;
}

.page-about .ab-close__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}

.page-about .ab-close__actions .ht-btn--outline {
  color: var(--ht-snow);
  border-color: rgba(247, 249, 252, 0.42);
}

.page-about .ab-close__actions .ht-btn--outline:hover,
.page-about .ab-close__actions .ht-btn--outline:focus-visible {
  color: var(--ht-snow);
  border-color: var(--ht-gold);
  background: rgba(232, 163, 61, 0.16);
}

/* ============ 响应式 ============ */
@media (min-width: 640px) {
  .page-about .ab-hero {
    padding: 30px 0 60px;
  }

  .page-about .ab-stats {
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  }

  .page-about .ab-close__panel {
    padding: 44px 40px 44px 46px;
    grid-template-columns: minmax(0, 1fr);
  }
}

@media (min-width: 900px) {
  .page-about .ab-hero {
    padding: 42px 0 78px;
  }

  .page-about .ab-hero__slant {
    display: block;
    position: absolute;
    top: -8%;
    right: -9%;
    width: 58%;
    height: 116%;
    background: linear-gradient(152deg, var(--ht-blue) 0%, var(--ht-blue-deep) 62%, #04213d 100%);
    clip-path: polygon(27% 0, 100% 0, 100% 100%, 0 100%);
  }

  .page-about .ab-hero__slant::after {
    content: "";
    position: absolute;
    left: 27%;
    top: 0;
    bottom: 0;
    width: 5px;
    background: var(--ht-red);
    transform: skewX(-11deg);
    transform-origin: top left;
    opacity: 0.9;
  }

  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 1.02fr) minmax(0, 0.98fr);
    align-items: center;
    gap: 54px;
  }

  .page-about .ab-hero__copy .ht-lede {
    font-size: 17px;
  }

  .page-about .ab-hero__figure {
    transform: translateY(14px);
  }

  .page-about .ab-hero__figure img {
    box-shadow: 0 30px 60px -34px rgba(4, 33, 61, 0.85);
  }

  .page-about .ab-chapter__grid {
    grid-template-columns: var(--ab-aside-w) minmax(0, 1fr);
    gap: 64px;
    align-items: start;
  }

  .page-about .ab-chapter--flip .ab-chapter__grid {
    grid-template-columns: minmax(0, 1fr) var(--ab-aside-w);
  }

  .page-about .ab-chapter--flip .ab-chapter__aside {
    order: 2;
    padding-left: 0;
    padding-right: 14px;
    border-left: 0;
    border-right: 3px solid var(--ht-green);
    text-align: right;
  }

  .page-about .ab-chapter--flip .ab-chapter__aside .ht-note {
    margin-left: auto;
  }

  .page-about .ab-chapter__aside {
    position: sticky;
    top: 108px;
  }

  .page-about .ab-chapter__figure--wide {
    margin-left: -6%;
    margin-right: 0;
  }

  .page-about .ab-close__panel {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: end;
    gap: 32px;
    padding: 52px 48px 52px 54px;
  }

  .page-about .ab-close__actions {
    justify-content: flex-end;
    padding-bottom: 4px;
  }
}

@media (min-width: 1180px) {
  .page-about .ab-stats {
    grid-template-columns: repeat(6, minmax(0, 1fr));
  }

  .page-about .ab-track {
    padding-left: 40px;
  }

  .page-about .ab-track__item::before {
    left: -38px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-link,
  .page-about .ab-index__link,
  .page-about .ab-track__item::before,
  .page-about .ab-track__trigger,
  .page-about .ab-fold__item .ht-disclosure__trigger {
    transition: none;
  }
}