.page-about {
  --about-dot: 15px;
  color: var(--fg);
  font-family: var(--font-body);
  padding-bottom: clamp(48px, 8vw, 96px);
}

.page-about .breadcrumb {
  margin: 20px 0 0;
}

.page-about .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}

/* ============ 首屏 ============ */
.page-about .intro {
  position: relative;
  padding: 30px 0 42px;
  border-bottom: 1px solid var(--line);
  overflow: hidden;
}

.page-about .intro::before {
  content: "";
  position: absolute;
  top: -44px;
  right: -8%;
  width: min(560px, 64%);
  height: 268px;
  background: linear-gradient(140deg, rgba(43, 227, 214, 0.2) 0%, rgba(255, 179, 60, 0.08) 46%, rgba(201, 60, 27, 0) 74%);
  clip-path: polygon(20% 0, 100% 0, 100% 100%, 0 58%);
  pointer-events: none;
}

.page-about .intro::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 62%;
  height: 1px;
  background: linear-gradient(90deg, var(--cyan), transparent);
  opacity: 0.55;
}

.page-about .intro > * {
  position: relative;
  z-index: 1;
}

.page-about .intro__eyebrow {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.22em;
  color: var(--cyan);
}

.page-about .intro__title {
  margin: 0 0 18px;
  max-width: 22ch;
  font-family: var(--font-display);
  font-size: clamp(1.85rem, 6.4vw, 3.4rem);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: -0.01em;
  color: var(--fg);
}

.page-about .intro__lead {
  margin: 0;
  max-width: 62ch;
  font-size: 1rem;
  line-height: 1.75;
  color: var(--fg-2);
}

.page-about .intro__facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 30px 0 0;
  padding: 0;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .intro__facts > div {
  background: var(--bg);
  padding: 14px 16px 16px;
}

.page-about .intro__facts dt {
  margin: 0 0 6px;
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  color: var(--gray);
}

.page-about .intro__facts dd {
  margin: 0;
  font-size: 0.95rem;
  color: var(--fg-2);
}

.page-about .intro__facts .num {
  font-size: 1.45rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--amber);
}

/* ============ 章节通用 ============ */
.page-about .sec {
  --accent: var(--cyan);
  padding-top: clamp(36px, 6vw, 64px);
  border-top: 1px solid var(--line-soft);
}

.page-about .intro + .sec {
  padding-top: clamp(28px, 5vw, 52px);
  border-top: 0;
}

.page-about .sec--tier { --accent: var(--amber); }
.page-about .sec--cats { --accent: var(--magenta); }
.page-about .sec--rhythm { --accent: var(--cyan); }
.page-about .sec--team { --accent: var(--amber); }
.page-about .sec--history { --accent: var(--cyan); }
.page-about .sec--border { --accent: var(--rust); }

.page-about .sec-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 4px 16px;
  align-items: start;
  margin-bottom: clamp(20px, 3.5vw, 32px);
}

.page-about .chapter-no {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(2.1rem, 7vw, 3.5rem);
  font-weight: 700;
  line-height: 0.9;
  letter-spacing: -0.05em;
  color: var(--accent);
}

.page-about .chapter-title {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 3.8vw, 1.7rem);
  font-weight: 700;
  line-height: 1.26;
  letter-spacing: 0.01em;
  color: var(--fg);
}

.page-about .sec-head__sub {
  margin: 8px 0 0;
  max-width: 56ch;
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--gray);
}

/* ============ 01 四类内容 ============ */
.page-about .scope-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .scope-item {
  background: var(--panel);
  padding: 18px 16px 22px;
  transition: background var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.page-about .scope-item:hover,
.page-about .scope-item:focus-within {
  background: #132039;
  transform: translateY(-2px);
}

.page-about .scope-item__idx {
  display: block;
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.18em;
  color: var(--accent);
}

.page-about .scope-item h3 {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--fg);
}

.page-about .scope-item p {
  margin: 0;
  font-size: 0.875rem;
  line-height: 1.72;
  color: var(--fg-2);
}

/* ============ 02 档位表 ============ */
.page-about .tier-scroll {
  overflow-x: auto;
  border: 1px solid var(--line);
  background: var(--panel);
  -webkit-overflow-scrolling: touch;
}

.page-about .tier-table {
  width: 100%;
  min-width: 760px;
  border-collapse: collapse;
}

.page-about .tier-table caption {
  text-align: left;
}

.page-about .tier-table thead th {
  padding: 12px 16px;
  text-align: left;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0.14em;
  color: var(--gray);
  border-bottom: 1px solid var(--line);
  white-space: nowrap;
}

.page-about .tier-table tbody th,
.page-about .tier-table tbody td {
  padding: 15px 16px;
  text-align: left;
  vertical-align: top;
  font-size: 0.85rem;
  line-height: 1.6;
  color: var(--fg-2);
  border-bottom: 1px solid var(--line-soft);
}

.page-about .tier-table tbody tr:last-child th,
.page-about .tier-table tbody tr:last-child td {
  border-bottom: 0;
}

.page-about .tier-table tbody tr {
  transition: background var(--dur) var(--ease);
}

.page-about .tier-table tbody tr:hover {
  background: rgba(43, 227, 214, 0.05);
}

.page-about .tier-table .tier-range {
  font-family: var(--font-mono);
  font-size: 0.92rem;
  color: var(--amber);
  white-space: nowrap;
}

.page-about .tier-chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 700;
  color: var(--bg);
}

.page-about .tier-chip--1 { background: var(--t1); }
.page-about .tier-chip--2 { background: var(--t2); }
.page-about .tier-chip--3 { background: var(--t3); }
.page-about .tier-chip--4 { background: var(--t4); }
.page-about .tier-chip--5 { background: var(--t5); }

.page-about .tier-note {
  margin: 16px 0 0;
  padding-left: 14px;
  border-left: 2px solid var(--amber);
  font-size: 0.82rem;
  line-height: 1.72;
  color: var(--gray);
}

/* ============ 03 十二类 ============ */
.page-about .cat-wrap {
  display: grid;
  gap: 24px;
}

.page-about .cat-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .cat-list li {
  display: flex;
  flex-direction: column;
  gap: 5px;
  background: var(--bg);
  padding: 12px 12px 14px;
  transition: background var(--dur) var(--ease);
}

.page-about .cat-list li:hover {
  background: #101c30;
}

.page-about .cat-list__no {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.12em;
  color: var(--magenta);
}

.page-about .cat-list__name {
  font-size: 0.92rem;
  color: var(--fg);
}

.page-about .cat-list__count {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--amber);
}

.page-about .cat-figure {
  margin: 0;
}

.page-about .cat-figure img,
.page-about .rhythm__figure img,
.page-about .team-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .cats-note {
  margin: 20px 0 0;
  max-width: 68ch;
  font-size: 0.875rem;
  line-height: 1.72;
  color: var(--fg-2);
}

.page-about .cats-note a {
  color: var(--cyan);
}

/* ============ 04 复核节奏 ============ */
.page-about .rhythm {
  display: grid;
  gap: 24px;
}

.page-about .rhythm__figure {
  margin: 0;
}

.page-about .rhythm__list {
  margin: 0;
  padding: 0;
}

.page-about .rhythm__item {
  padding: 14px 0 14px 16px;
  border-left: 2px solid var(--line);
  border-bottom: 1px solid var(--line-soft);
  transition: border-left-color var(--dur) var(--ease);
}

.page-about .rhythm__item:first-child {
  padding-top: 4px;
}

.page-about .rhythm__item:last-child {
  border-bottom: 0;
}

.page-about .rhythm__item:hover {
  border-left-color: var(--cyan);
}

.page-about .rhythm__item dt {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  color: var(--cyan);
}

.page-about .rhythm__item dd {
  margin: 8px 0 0;
  font-size: 0.86rem;
  line-height: 1.72;
  color: var(--fg-2);
}

/* ============ 05 团队 ============ */
.page-about .team-bars {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 12px;
}

.page-about .team-bars__row {
  display: grid;
  grid-template-columns: minmax(72px, 110px) minmax(0, 1fr) 44px;
  align-items: center;
  gap: 12px;
}

.page-about .team-bars__label {
  font-size: 0.85rem;
  color: var(--fg-2);
}

.page-about .team-bars__track {
  display: block;
  height: 10px;
  background: var(--panel);
  border: 1px solid var(--line);
}

.page-about .team-bars__fill {
  display: block;
  width: var(--w, 0%);
  height: 100%;
  transition: width var(--dur) var(--ease);
}

.page-about .team-bars__fill--a { background: var(--t1); }
.page-about .team-bars__fill--b { background: var(--t2); }
.page-about .team-bars__fill--c { background: var(--t3); }
.page-about .team-bars__fill--d { background: var(--t4); }

.page-about .team-bars__num {
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 700;
  text-align: right;
  color: var(--amber);
}

.page-about .team-note {
  margin: 22px 0 0;
  max-width: 70ch;
  font-size: 0.875rem;
  line-height: 1.75;
  color: var(--fg-2);
}

.page-about .team-figure {
  margin: 26px 0 0;
}

/* ============ 06 时间线 ============ */
.page-about .timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 32px;
  list-style: none;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(180deg, var(--t1) 0%, var(--t3) 48%, var(--t5) 100%);
}

.page-about .timeline__item {
  position: relative;
  padding: 0 0 26px;
  outline: none;
}

.page-about .timeline__item:last-child {
  padding-bottom: 0;
}

.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: -32px;
  top: 5px;
  width: var(--about-dot);
  height: var(--about-dot);
  border-radius: 50%;
  background: var(--bg);
  border: 1px solid var(--line);
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.page-about .timeline__item:hover::before,
.page-about .timeline__item:focus::before,
.page-about .timeline__item:focus-within::before {
  background: var(--cyan);
  border-color: var(--cyan);
  transform: scale(1.15);
}

.page-about .timeline__item:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 6px;
}

.page-about .timeline__year {
  display: block;
  font-family: var(--font-mono);
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--amber);
}

.page-about .timeline__body h3 {
  margin: 6px 0 6px;
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--fg);
}

.page-about .timeline__body p {
  margin: 0;
  max-width: 62ch;
  font-size: 0.86rem;
  line-height: 1.7;
  color: var(--fg-2);
}

.page-about .timeline__more {
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  transform: translateY(-4px);
  margin-top: 0;
  color: var(--gray);
  transition: max-height 200ms var(--ease), opacity 200ms var(--ease), transform 200ms var(--ease), margin-top 200ms var(--ease);
}

.page-about .timeline__item:hover .timeline__more,
.page-about .timeline__item:focus .timeline__more,
.page-about .timeline__item:focus-within .timeline__more {
  max-height: 160px;
  opacity: 1;
  transform: none;
  margin-top: 8px;
}

/* ============ 07 合作与纠错 ============ */
.page-about .border-wrap {
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .border-card {
  background: var(--panel);
  padding: 22px 20px 24px;
}

.page-about .border-card h3 {
  margin: 0 0 12px;
  font-family: var(--font-display);
  font-size: 1.08rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--rust);
}

.page-about .border-card p {
  margin: 0 0 12px;
  font-size: 0.875rem;
  line-height: 1.72;
  color: var(--fg-2);
}

.page-about .border-card p:last-child {
  margin-bottom: 0;
}

.page-about .border-card__stat {
  font-size: 0.82rem;
  color: var(--gray);
}

.page-about .border-card__stat .num {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--amber);
}

.page-about .border-card__link a {
  color: var(--cyan);
}

/* ============ 相关栏目 ============ */
.page-about .next-links {
  margin-top: clamp(40px, 7vw, 72px);
  padding-top: 26px;
  border-top: 1px solid var(--line);
}

.page-about .next-links__title {
  margin: 0 0 16px;
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--fg);
}

.page-about .next-links ul {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .next-links a {
  display: block;
  padding: 18px 16px;
  background: var(--bg);
  font-size: 0.875rem;
  line-height: 1.6;
  color: var(--fg-2);
  text-decoration: none;
  transition: background var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .next-links a:hover,
.page-about .next-links a:focus-visible {
  background: var(--panel);
  color: var(--cyan);
}

/* ============ 响应式 ============ */
@media (min-width: 600px) {
  .page-about .scope-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

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

@media (min-width: 720px) {
  .page-about .intro__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

@media (min-width: 900px) {
  .page-about .cat-wrap {
    grid-template-columns: minmax(0, 1fr) minmax(0, 0.85fr);
    gap: 32px;
    align-items: start;
  }

  .page-about .rhythm {
    grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
    gap: 32px;
    align-items: start;
  }

  .page-about .team-bars__row {
    grid-template-columns: 130px minmax(0, 1fr) 48px;
  }
}

@media (min-width: 1024px) {
  .page-about .scope-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}

.page-about {
  --w: 1rem;
}