.page-about {
  --ab-body-text: #C9DAEC;
  --ab-ink-line: rgba(39, 65, 95, 0.65);
  --ab-glow-cyan: rgba(53, 240, 208, 0.12);
  --ab-glow-orange: rgba(255, 138, 61, 0.1);
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  padding-block: clamp(1.5rem, 4vw, 2.75rem) clamp(2rem, 5vw, 3.5rem);
}

.page-about .ab-hero::before {
  content: "";
  position: absolute;
  inset: -30% -10% auto -10%;
  height: 78%;
  background:
    radial-gradient(58% 62% at 78% 26%, var(--ab-glow-cyan), transparent 72%),
    radial-gradient(48% 52% at 10% 4%, var(--ab-glow-orange), transparent 70%);
  pointer-events: none;
  z-index: -1;
}

.page-about .ab-hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(1.5rem, 4vw, 3rem);
  align-items: end;
  margin-top: clamp(1.25rem, 3vw, 2rem);
}

.page-about .ab-hero__intro h1 {
  margin: 0.55rem 0 0;
  font-family: var(--font-display);
  font-size: clamp(1.85rem, 6vw, 3.35rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--c-text);
  text-wrap: balance;
}

.page-about .ab-hero__intro .lede {
  margin: 1rem 0 0;
  max-width: 46ch;
  font-size: clamp(0.98rem, 2.2vw, 1.1rem);
  line-height: 1.85;
  color: var(--ab-body-text);
}

.page-about .ab-hero__media {
  position: relative;
  border-left: 3px solid var(--c-cyan);
}

.page-about .ab-hero__media::after {
  content: "";
  position: absolute;
  top: 0;
  left: -3px;
  width: 3px;
  height: 38%;
  background: var(--c-orange);
}

/* ---------- 数字带 ---------- */
.page-about .ab-statbar {
  list-style: none;
  margin: clamp(1.75rem, 4vw, 2.75rem) 0 0;
  padding: 1.15rem 0 0;
  border-top: 1px solid var(--c-line);
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.15rem 1.5rem;
}

.page-about .ab-statbar__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.45rem, 3.6vw, 2.05rem);
  line-height: 1;
  color: var(--c-cyan);
  letter-spacing: -0.02em;
}

.page-about .ab-statbar__label {
  display: block;
  margin-top: 0.45rem;
  font-size: 0.8rem;
  line-height: 1.55;
  color: var(--c-muted);
}

/* ---------- 主壳：左窄右宽 ---------- */
.page-about .ab-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(1.75rem, 4vw, 3.25rem);
  padding-bottom: clamp(3rem, 8vw, 5.5rem);
}

.page-about .ab-toc {
  border: 1px solid var(--c-line);
  border-left: 3px solid var(--c-cyan);
  background: linear-gradient(180deg, rgba(20, 38, 61, 0.92), rgba(13, 27, 46, 0.72));
  padding: 1.05rem 1rem 1.2rem;
}

.page-about .ab-toc__title {
  margin: 0 0 0.7rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.2em;
  color: var(--c-amber);
}

.page-about .ab-toc__list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .ab-toc__list a {
  display: flex;
  align-items: baseline;
  gap: 0.65rem;
  padding: 0.55rem 0.35rem;
  font-size: 0.92rem;
  line-height: 1.5;
  color: var(--c-muted);
  text-decoration: none;
  border-bottom: 1px dashed var(--ab-ink-line);
  transition: color 0.18s var(--ease), background-color 0.18s var(--ease), padding-left 0.18s var(--ease);
}

.page-about .ab-toc__list li:last-child a {
  border-bottom: 0;
}

.page-about .ab-toc__list .index-number {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--c-blue);
}

.page-about .ab-toc__list a:hover,
.page-about .ab-toc__list a:focus-visible {
  color: var(--c-text);
  background-color: rgba(53, 240, 208, 0.08);
  padding-left: 0.7rem;
}

/* ---------- 章节 ---------- */
.page-about .ab-section {
  padding-block: clamp(1.75rem, 4.5vw, 2.9rem);
  border-top: 1px solid var(--c-line);
  scroll-margin-top: 96px;
}

.page-about .ab-body > .ab-section:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .ab-section__head {
  display: flex;
  align-items: baseline;
  gap: 0.85rem;
  padding-bottom: 0.7rem;
  margin-bottom: 1.2rem;
  border-bottom: 1px solid var(--ab-ink-line);
  position: relative;
}

.page-about .ab-section__head::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 46px;
  height: 2px;
  background: var(--c-orange);
}

.page-about .ab-section__head .index-number {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--c-orange);
  letter-spacing: 0.1em;
}

.page-about .ab-section__head h2 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.35rem, 3.8vw, 1.95rem);
  line-height: 1.25;
  letter-spacing: -0.01em;
  color: var(--c-text);
}

.page-about .ab-prose p {
  margin: 0 0 1rem;
  max-width: 68ch;
  font-size: var(--fs-body);
  line-height: 1.88;
  color: var(--ab-body-text);
}

.page-about .ab-prose p:last-child {
  margin-bottom: 0;
}

/* ---------- 旁注折叠 ---------- */
.page-about .ab-note {
  margin-top: 1.4rem;
  max-width: 68ch;
}

.page-about .ab-note details {
  border: 1px solid var(--c-line);
  border-left: 2px solid var(--c-orange);
  background: var(--c-panel);
  padding: 0.85rem 1rem 0.95rem;
}

.page-about .ab-note summary {
  cursor: pointer;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.05em;
  color: var(--c-amber);
}

.page-about .ab-note summary::-webkit-details-marker {
  display: none;
}

.page-about .ab-note summary::before {
  content: "+";
  display: inline-block;
  width: 1.1em;
  color: var(--c-orange);
}

.page-about .ab-note details[open] summary::before {
  content: "\2212";
}

.page-about .ab-note summary:focus-visible {
  outline: 2px solid var(--c-cyan);
  outline-offset: 2px;
}

.page-about .ab-note p {
  margin: 0.7rem 0 0;
  font-size: 0.9rem;
  line-height: 1.8;
  color: var(--c-muted);
}

/* ---------- 流程 ---------- */
.page-about .ab-flow-media {
  margin: clamp(1.35rem, 3vw, 2rem) 0 0;
}

.page-about .ab-flow {
  list-style: none;
  margin: 1.35rem 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background-color: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .ab-flow li {
  background-color: var(--c-panel);
  padding: 1.1rem 1.1rem 1.25rem;
}

.page-about .ab-flow__idx {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.18em;
  color: var(--c-orange);
  margin-bottom: 0.6rem;
}

.page-about .ab-flow h3 {
  margin: 0 0 0.45rem;
  font-size: 1rem;
  font-weight: 600;
  color: var(--c-text);
}

.page-about .ab-flow p {
  margin: 0;
  font-size: 0.86rem;
  line-height: 1.72;
  color: var(--c-muted);
}

/* ---------- 团队岗位 ---------- */
.page-about .ab-roles {
  list-style: none;
  margin: 1.3rem 0 0;
  padding: 0;
  border-top: 1px solid var(--c-line);
}

.page-about .ab-roles li {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0.4rem;
  padding: 1.05rem 0 1.05rem 1rem;
  border-bottom: 1px solid var(--c-line);
}

.page-about .ab-roles li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 1.35rem;
  width: 3px;
  height: 1.6rem;
  background: linear-gradient(180deg, var(--c-cyan), rgba(53, 240, 208, 0));
}

.page-about .ab-roles__key {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.22em;
  color: var(--c-cyan);
}

.page-about .ab-roles p {
  margin: 0;
  max-width: 62ch;
  font-size: 0.92rem;
  line-height: 1.8;
  color: var(--ab-body-text);
}

/* ---------- 里程碑时间轴 ---------- */
.page-about .ab-timeline-media {
  position: relative;
  margin: clamp(1.35rem, 3vw, 2rem) 0 0;
}

.page-about .ab-milestones {
  list-style: none;
  margin: 1.6rem 0 0;
  padding: 1.25rem 0 0.75rem;
  border-top: 2px solid var(--c-line);
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: 228px;
  gap: 1.15rem;
  overflow-x: auto;
  overscroll-behavior-x: contain;
  scroll-snap-type: x proximity;
}

.page-about .ab-milestones::-webkit-scrollbar {
  height: 6px;
}

.page-about .ab-milestones::-webkit-scrollbar-track {
  background: var(--c-panel);
}

.page-about .ab-milestones::-webkit-scrollbar-thumb {
  background: var(--c-line);
}

.page-about .ab-milestone {
  position: relative;
  scroll-snap-align: start;
  padding-right: 0.5rem;
}

.page-about .ab-milestone__dot {
  display: block;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--c-blue);
  margin-bottom: 0.85rem;
  transition: background-color 0.2s var(--ease), box-shadow 0.2s var(--ease);
}

.page-about .ab-milestone:hover .ab-milestone__dot,
.page-about .ab-milestone:focus-within .ab-milestone__dot {
  background: var(--c-cyan);
  box-shadow: 0 0 0 5px rgba(53, 240, 208, 0.16);
}

.page-about .ab-milestone__stage {
  display: block;
  margin-bottom: 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  color: var(--c-amber);
}

.page-about .ab-milestone h3 {
  margin: 0 0 0.45rem;
  font-size: 1rem;
  line-height: 1.4;
  color: var(--c-text);
}

.page-about .ab-milestone p {
  margin: 0;
  font-size: 0.85rem;
  line-height: 1.7;
  color: var(--c-muted);
}

/* ---------- 下一步 ---------- */
.page-about .ab-next {
  margin-top: clamp(1.5rem, 4vw, 2.5rem);
  padding: clamp(1.35rem, 3.5vw, 2rem);
  border: 1px solid var(--c-line);
  background: linear-gradient(135deg, rgba(20, 38, 61, 0.95), rgba(6, 16, 31, 0.6));
  position: relative;
}

.page-about .ab-next::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, var(--c-cyan), var(--c-orange) 45%, rgba(53, 240, 208, 0));
}

.page-about .ab-next__head {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.page-about .ab-next__head .index-number {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--c-orange);
}

.page-about .ab-next__head h2 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.2rem, 3.4vw, 1.6rem);
  color: var(--c-text);
}

.page-about .ab-next__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background-color: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .ab-next__list li {
  background-color: var(--c-panel);
  padding: 0.95rem 1rem;
}

.page-about .ab-next__list a {
  display: inline-block;
  font-size: 0.98rem;
  font-weight: 600;
  color: var(--c-cyan);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.18s var(--ease), color 0.18s var(--ease);
}

.page-about .ab-next__list a:hover,
.page-about .ab-next__list a:focus-visible {
  color: var(--c-text);
  border-bottom-color: var(--c-orange);
}

.page-about .ab-next__list span {
  display: block;
  margin-top: 0.3rem;
  font-size: 0.83rem;
  line-height: 1.65;
  color: var(--c-muted);
}

/* ---------- 响应式 ---------- */
@media (min-width: 700px) {
  .page-about .ab-flow {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .ab-roles li {
    grid-template-columns: 6rem minmax(0, 1fr);
    align-items: baseline;
    gap: 1.5rem;
  }

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

@media (min-width: 900px) {
  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  }

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

  .page-about .ab-hero__media {
    margin-top: 1.5rem;
  }
}

@media (min-width: 1024px) {
  .page-about .ab-shell {
    grid-template-columns: minmax(0, 4fr) minmax(0, 8fr);
    align-items: start;
  }

  .page-about .ab-toc {
    position: sticky;
    top: 96px;
  }

  .page-about .ab-milestones {
    grid-auto-columns: 250px;
  }
}

@media (min-width: 1200px) {
  .page-about .ab-flow {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-toc__list a,
  .page-about .ab-milestone__dot,
  .page-about .ab-next__list a {
    transition: none;
  }

  .page-about .ab-milestones {
    scroll-snap-type: none;
  }
}