.page-about {
  position: relative;
  background:
    linear-gradient(rgba(0, 229, 255, 0.025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 229, 255, 0.025) 1px, transparent 1px);
  background-size: 48px 48px;
  overflow-x: hidden;
}

.page-about .section {
  margin-top: clamp(72px, 10vw, 140px);
}

.page-about .section-head {
  position: relative;
  display: grid;
  gap: 6px;
  max-width: 760px;
}

.page-about .section-index {
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: 0.18em;
  color: var(--gold);
}

.page-about .section-title {
  font-family: var(--font-heading);
  font-size: clamp(30px, 5vw, 54px);
  line-height: 1.08;
  letter-spacing: 0.02em;
  margin-top: 8px;
}

.page-about .section-sub {
  font-size: 15px;
  color: var(--text-muted);
}

/* ===== hero ===== */
.ab-hero {
  position: relative;
  padding-top: 28px;
}

.ab-hero::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 72%;
  height: 420px;
  background: linear-gradient(135deg, rgba(180, 76, 255, 0.16), rgba(0, 229, 255, 0.03));
  clip-path: polygon(18% 0, 100% 0, 100% 100%, 0 100%);
  pointer-events: none;
}

.ab-hero__inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 32px;
  align-items: center;
}

.ab-hero__intro {
  max-width: 640px;
}

.ab-hero__title {
  font-family: var(--font-heading);
  font-size: clamp(38px, 6vw, 82px);
  font-weight: 700;
  line-height: 1.04;
  letter-spacing: 0.02em;
  margin: 14px 0 0;
}

.ab-hero__subtitle {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: 14px;
  letter-spacing: 0.22em;
  color: var(--accent-blue);
  background: linear-gradient(90deg, rgba(0, 229, 255, 0.16), transparent);
  padding: 8px 18px 8px 10px;
  margin-top: 16px;
  clip-path: polygon(0 0, calc(100% - 10px) 0, 100% 100%, 10px 100%);
}

.ab-hero__desc {
  font-size: 16px;
  line-height: 1.8;
  color: var(--text-muted);
  margin-top: 20px;
  max-width: 54ch;
}

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

.ab-hero__figure {
  margin: 0;
  max-width: 640px;
  aspect-ratio: 16 / 10;
}

.ab-hero__figure img,
.ab-coverage__map img,
.ab-ecosystem__figure img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* snapshot */
.ab-hero__snapshot {
  border-top: 1px solid var(--hairline);
  border-bottom: 1px solid var(--hairline);
  margin-top: 48px;
}

.ab-hero__snapshot-list {
  display: grid;
  grid-template-columns: 1fr;
  margin: 0;
  padding: 0;
}

.ab-hero__snapshot-item {
  display: grid;
  gap: 6px;
  padding: 18px 20px;
  border-bottom: 1px solid var(--hairline);
}

.ab-hero__snapshot-item:last-child {
  border-bottom: 0;
}

.ab-hero__snapshot-item dt {
  font-size: 13px;
  color: var(--text-muted);
  letter-spacing: 0.04em;
}

.ab-hero__snapshot-item dd {
  font-family: var(--font-mono);
  font-size: 16px;
  color: var(--text-primary);
  margin: 0;
}

/* ===== creed ===== */
.ab-creed__grid {
  display: grid;
  gap: 20px;
  margin-top: 44px;
}

.ab-creed__card {
  position: relative;
  background: linear-gradient(180deg, rgba(13, 42, 77, 0.72), rgba(13, 42, 77, 0.24));
  border: 1px solid var(--hairline);
  padding: 32px 24px 28px;
  clip-path: polygon(0 0, calc(100% - 18px) 0, 100% 18px, 100% 100%, 18px 100%, 0 calc(100% - 18px));
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.ab-creed__card:hover {
  border-color: rgba(0, 229, 255, 0.4);
  box-shadow: 0 0 24px rgba(0, 229, 255, 0.06);
}

.ab-creed__num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 46px;
  height: 46px;
  font-family: var(--font-mono);
  font-size: 18px;
  color: var(--gold);
  border: 1px solid rgba(224, 184, 120, 0.45);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 8px), calc(100% - 8px) 100%, 0 100%);
  margin-bottom: 20px;
}

.ab-creed__heading {
  font-family: var(--font-heading);
  font-size: 19px;
  letter-spacing: 0.04em;
}

.ab-creed__text {
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-muted);
  margin-top: 10px;
}

/* ===== coverage ===== */
.ab-coverage__layout {
  display: grid;
  gap: 32px;
  margin-top: 44px;
}

.ab-coverage__map {
  position: relative;
  margin: 0;
  aspect-ratio: 3 / 2;
}

.ab-coverage__map::after {
  content: "12 支战队 · 200+ 选手档案";
  position: absolute;
  left: 12px;
  bottom: 44px;
  background: rgba(8, 26, 46, 0.88);
  border: 1px solid rgba(0, 229, 255, 0.3);
  padding: 10px 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--accent-blue);
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.ab-coverage__map:hover::after {
  opacity: 1;
  transform: translateY(0);
}

.ab-coverage__stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1px;
  background: var(--hairline);
  border: 1px solid var(--hairline);
}

.page-about .ab-coverage__stats .stat {
  margin: 0;
  background: rgba(13, 42, 77, 0.9);
  padding: 22px 16px;
}

.page-about .stat__value {
  font-family: var(--font-heading);
  font-size: 34px;
  line-height: 1;
  color: var(--accent-blue);
}

.page-about .stat__label {
  font-size: 13px;
  color: var(--text-muted);
  margin-top: 8px;
  display: block;
}

/* tabs */
.ab-tabs {
  position: relative;
  margin-top: 48px;
  border: 1px solid rgba(0, 229, 255, 0.22);
  background: rgba(13, 42, 77, 0.5);
}

.ab-tabs__input {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  opacity: 0;
}

.ab-tabs__nav {
  display: flex;
  border-bottom: 1px solid var(--hairline);
}

.ab-tabs__label {
  flex: 1;
  padding: 16px 12px;
  text-align: center;
  font-family: var(--font-heading);
  font-size: 14px;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}

.ab-tabs__input--schedule:checked ~ .ab-tabs__nav .ab-tabs__label--schedule,
.ab-tabs__input--points:checked ~ .ab-tabs__nav .ab-tabs__label--points,
.ab-tabs__input--profiles:checked ~ .ab-tabs__nav .ab-tabs__label--profiles {
  color: var(--accent-blue);
  border-bottom-color: var(--accent-blue);
  background: rgba(0, 229, 255, 0.07);
}

.ab-tabs__input--schedule:focus-visible ~ .ab-tabs__nav .ab-tabs__label--schedule,
.ab-tabs__input--points:focus-visible ~ .ab-tabs__nav .ab-tabs__label--points,
.ab-tabs__input--profiles:focus-visible ~ .ab-tabs__nav .ab-tabs__label--profiles {
  outline: 2px solid var(--accent-blue);
  outline-offset: -2px;
}

.ab-tabs__panel {
  display: none;
  padding: 28px 24px 32px;
}

.ab-tabs__input--schedule:checked ~ .ab-tabs__panels .ab-tabs__panel-1,
.ab-tabs__input--points:checked ~ .ab-tabs__panels .ab-tabs__panel-2,
.ab-tabs__input--profiles:checked ~ .ab-tabs__panels .ab-tabs__panel-3 {
  display: block;
}

.ab-tabs__panel-title {
  font-family: var(--font-heading);
  font-size: 20px;
  letter-spacing: 0.04em;
}

.ab-tabs__panel-status {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--accent-green);
  margin-top: 10px;
}

.ab-tabs__panel-text {
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-muted);
  margin-top: 12px;
  max-width: 68ch;
}

/* ===== milestones ===== */
.ab-milestones__track {
  position: relative;
  display: flex;
  gap: 20px;
  list-style: none;
  margin: 48px 0 0;
  padding: 24px 4px 16px;
  overflow-x: auto;
  scroll-snap-type: x proximity;
  scrollbar-width: thin;
  scrollbar-color: rgba(224, 184, 120, 0.45) rgba(13, 42, 77, 0.6);
}

.ab-milestones__track::before {
  content: "";
  position: absolute;
  top: 31px;
  left: 4px;
  right: 4px;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(224, 184, 120, 0.5), rgba(224, 184, 120, 0.5), transparent);
}

.ab-milestones__item {
  position: relative;
  flex: 0 0 250px;
  scroll-snap-align: start;
  padding-left: 16px;
}

.ab-milestones__node {
  position: absolute;
  top: 24px;
  left: 24px;
  width: 14px;
  height: 14px;
  background: var(--gold);
  transform: rotate(45deg);
  box-shadow: 0 0 12px rgba(224, 184, 120, 0.5);
  z-index: 1;
}

.ab-milestones__card {
  min-height: 168px;
  padding: 28px 22px 20px;
  border: 1px solid var(--hairline);
  background: linear-gradient(160deg, rgba(13, 42, 77, 0.88), rgba(8, 26, 46, 0.6));
}

.ab-milestones__version {
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--accent-purple);
  letter-spacing: 0.12em;
}

.ab-milestones__heading {
  font-family: var(--font-heading);
  font-size: 19px;
  margin-top: 10px;
}

.ab-milestones__text {
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-muted);
  margin-top: 10px;
}

.ab-milestones__hint {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-muted);
  text-align: right;
  margin-top: 12px;
}

/* ===== ecosystem ===== */
.ab-ecosystem__layout {
  display: grid;
  gap: 40px;
  margin-top: 44px;
}

.ab-ecosystem__row {
  display: grid;
  grid-template-columns: 64px 1fr;
  gap: 16px;
  padding: 22px 0;
  border-bottom: 1px solid var(--hairline);
}

.ab-ecosystem__row:first-child {
  padding-top: 0;
}

.ab-ecosystem__code {
  align-self: start;
  justify-self: start;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--gold);
  border: 1px solid rgba(224, 184, 120, 0.45);
  padding: 6px 8px;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 6px), calc(100% - 6px) 100%, 0 100%);
}

.ab-ecosystem__heading {
  font-family: var(--font-heading);
  font-size: 17px;
  letter-spacing: 0.04em;
}

.ab-ecosystem__text {
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-muted);
  margin-top: 8px;
}

.ab-ecosystem__figure {
  margin: 0;
  aspect-ratio: 2 / 1;
}

/* ===== finale ===== */
.ab-finale {
  margin-top: clamp(80px, 10vw, 144px);
  padding: 72px 0;
  background: linear-gradient(120deg, rgba(180, 76, 255, 0.16), rgba(0, 229, 255, 0.06));
  clip-path: polygon(0 3%, 100% 0, 100% 97%, 0 100%);
  text-align: center;
}

.ab-finale__title {
  font-family: var(--font-heading);
  font-size: clamp(28px, 4vw, 52px);
  line-height: 1.2;
}

.ab-finale__text {
  font-size: 15px;
  color: var(--text-muted);
  max-width: 58ch;
  margin: 16px auto 0;
}

.ab-finale__actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  margin-top: 28px;
}

/* ===== responsive ===== */
@media (min-width: 640px) {
  .ab-hero__snapshot-list {
    grid-template-columns: repeat(2, 1fr);
  }

  .ab-hero__snapshot-item:nth-child(odd) {
    border-right: 1px solid var(--hairline);
  }

  .ab-hero__snapshot-item:nth-child(3) {
    border-bottom: 1px solid var(--hairline);
  }

  .ab-hero__snapshot-item:nth-child(4) {
    border-bottom: 0;
  }
}

@media (hover: none) {
  .ab-coverage__map::after {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (min-width: 900px) {
  .ab-hero__inner {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    gap: 56px;
  }

  .ab-hero::before {
    height: 520px;
  }

  .ab-creed__grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 26px;
  }

  .ab-creed__card:nth-child(2) {
    transform: translateY(26px);
  }

  .ab-coverage__layout {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    align-items: start;
  }

  .ab-ecosystem__layout {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    align-items: center;
  }
}

@media (min-width: 1100px) {
  .ab-hero__snapshot-list {
    grid-template-columns: repeat(4, 1fr);
  }

  .ab-hero__snapshot-item {
    border-bottom: 0;
    border-right: 1px solid var(--hairline);
  }

  .ab-hero__snapshot-item:nth-child(3) {
    border-bottom: 0;
  }

  .ab-hero__snapshot-item:nth-child(4) {
    border-bottom: 0;
  }

  .ab-hero__snapshot-item:last-child {
    border-right: 0;
  }

  .ab-milestones__track {
    overflow: visible;
    padding-bottom: 8px;
  }

  .ab-milestones__item {
    flex: 1 1 0;
  }

  .ab-milestones__hint {
    display: none;
  }
}