.page-about {
  --about-rail: 288px;
  --about-hairline: rgba(174, 183, 192, 0.34);
}

/* ===== 通用链接 ===== */
.page-about .about-link {
  color: var(--signal-ink);
  text-decoration: none;
  border-bottom: 1px solid rgba(178, 58, 10, 0.38);
  padding-bottom: 1px;
  transition: color 0.18s ease, border-color 0.18s ease;
}
.page-about .about-link:hover {
  color: var(--signal);
  border-bottom-color: var(--signal);
}
.page-about .about-link:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

/* ===== 首屏 ===== */
.page-about .about-intro__grid {
  display: grid;
  gap: 36px;
  margin-top: 26px;
}
.page-about .about-intro__eyebrow {
  display: inline-block;
  font-family: var(--font-num);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.1em;
  color: var(--signal-ink);
  border-left: 2px solid var(--signal);
  padding-left: 10px;
  margin: 0 0 18px;
}
.page-about .about-intro h1 {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(30px, 7vw, 54px);
  line-height: 1.06;
  letter-spacing: -0.015em;
  color: var(--ink-950);
  margin: 0 0 20px;
  max-width: 15ch;
}
.page-about .about-intro__lead {
  font-size: 16.5px;
  line-height: 1.9;
  color: var(--ink-600);
  margin: 0 0 16px;
  max-width: 48ch;
}
.page-about .about-intro__aside {
  font-size: 14px;
  line-height: 1.85;
  color: var(--ink-600);
  margin: 0;
  max-width: 48ch;
}

.page-about .about-intro__facts {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-top: 34px;
  border-top: var(--line);
  border-left: var(--line);
}
.page-about .about-intro__fact {
  border-right: var(--line);
  border-bottom: var(--line);
  padding: 15px 14px 17px;
}
.page-about .about-intro__fact-num {
  display: block;
  font-family: var(--font-num);
  font-size: 26px;
  font-weight: 600;
  line-height: 1.1;
  color: var(--ink-950);
}
.page-about .about-intro__fact:first-child .about-intro__fact-num {
  color: var(--signal-ink);
}
.page-about .about-intro__fact-label {
  display: block;
  margin-top: 7px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--ink-600);
}

.page-about .about-intro__figure {
  margin: 0;
  max-width: 340px;
}
.page-about .about-intro__figure img {
  display: block;
  width: 100%;
  height: auto;
  border: var(--line);
  background: var(--paper-200);
  box-shadow: var(--shadow-soft);
}
.page-about .about-intro__figcap {
  margin-top: 12px;
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--ink-600);
}

/* ===== 阶段（时间轴 + 折叠面板） ===== */
.page-about .about-phases {
  display: grid;
  gap: 10px;
  margin-top: 34px;
}
.page-about .about-phases__rail {
  display: flex;
  flex-direction: column;
  position: relative;
}

.page-about .about-phase-btn {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  align-items: center;
  gap: 0 12px;
  width: 100%;
  text-align: left;
  background: transparent;
  border: 0;
  border-left: 2px solid var(--silver-200);
  padding: 13px 12px 13px 16px;
  cursor: pointer;
  font-family: inherit;
  font-size: inherit;
  color: var(--ink-600);
  transition: border-color 0.18s ease, background-color 0.18s ease, color 0.18s ease;
}
.page-about .about-phase-btn__num {
  grid-row: 1 / span 2;
  font-family: var(--font-num);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--silver-400);
  transition: color 0.18s ease;
}
.page-about .about-phase-btn__title {
  font-size: 15px;
  font-weight: 600;
  line-height: 1.4;
  color: inherit;
}
.page-about .about-phase-btn__era {
  grid-column: 2;
  font-size: 12px;
  font-weight: 300;
  line-height: 1.5;
  color: var(--silver-400);
}
.page-about .about-phase-btn:hover {
  border-left-color: var(--ink-600);
  color: var(--ink-950);
}
.page-about .about-phase-btn:hover .about-phase-btn__num {
  color: var(--ink-600);
}
.page-about .about-phase-btn[aria-selected="true"] {
  border-left-color: var(--signal);
  color: var(--ink-950);
  background: linear-gradient(90deg, rgba(235, 90, 22, 0.1), rgba(235, 90, 22, 0) 78%);
}
.page-about .about-phase-btn[aria-selected="true"] .about-phase-btn__num {
  color: var(--signal-ink);
}
.page-about .about-phase-btn:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: -2px;
}

.page-about .about-phase-panel {
  padding: 24px 0 0;
}
.page-about .about-phase-panel[hidden] {
  display: none;
}
.page-about .about-phase-panel__meta {
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--signal-ink);
  margin: 0 0 10px;
}
.page-about .about-phase-panel__title {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(22px, 3.6vw, 30px);
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--ink-950);
  margin: 0 0 14px;
}
.page-about .about-phase-panel__lead {
  font-size: 16px;
  line-height: 1.9;
  color: var(--ink-600);
  margin: 0 0 20px;
  max-width: 54ch;
}
.page-about .about-phase-panel__list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: var(--line);
  max-width: 62ch;
}
.page-about .about-phase-panel__list li {
  position: relative;
  padding: 12px 0 12px 22px;
  border-bottom: var(--line);
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--ink-600);
}
.page-about .about-phase-panel__list li::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 21px;
  width: 8px;
  height: 1px;
  background: var(--signal);
}

/* ===== 版本轨迹 ===== */
.page-about .about-versions {
  list-style: none;
  margin: 34px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  border-bottom: var(--line);
}
.page-about .about-version {
  display: grid;
  grid-template-columns: 52px minmax(0, 1fr);
  gap: 14px;
  padding: 16px 0;
  border-top: var(--line);
  align-items: start;
}
.page-about .about-version__num {
  font-family: var(--font-num);
  font-size: 19px;
  font-weight: 600;
  line-height: 1.35;
  letter-spacing: -0.02em;
  color: var(--silver-400);
  transition: color 0.18s ease;
}
.page-about .about-version:hover .about-version__num {
  color: var(--signal-ink);
}
.page-about .about-version__name {
  font-size: 16px;
  font-weight: 600;
  line-height: 1.5;
  color: var(--ink-950);
  margin: 0 0 4px;
}
.page-about .about-version__desc {
  font-size: 14px;
  line-height: 1.75;
  color: var(--ink-600);
  margin: 0;
}

/* ===== 统计标准修订 ===== */
.page-about .about-revisions {
  display: grid;
  gap: 32px;
  margin-top: 34px;
}
.page-about .about-revisions__aside {
  border-left: 2px solid var(--signal);
  padding: 4px 0 4px 20px;
}
.page-about .about-revisions__stat {
  font-family: var(--font-num);
  font-size: clamp(46px, 9vw, 68px);
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--ink-950);
  margin: 0;
}
.page-about .about-revisions__stat-label {
  font-size: 14px;
  font-weight: 600;
  color: var(--signal-ink);
  margin: 10px 0 0;
}
.page-about .about-revisions__stat-note {
  font-size: 14px;
  line-height: 1.85;
  color: var(--ink-600);
  margin: 12px 0 0;
  max-width: 34ch;
}
.page-about .about-revisions__list {
  list-style: none;
  margin: 0;
  padding: 0;
  counter-reset: rev;
}
.page-about .about-revisions__list li {
  position: relative;
  padding: 16px 0 16px 46px;
  border-top: var(--line);
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--ink-600);
}
.page-about .about-revisions__list li:last-child {
  border-bottom: var(--line);
}
.page-about .about-revisions__list li::before {
  counter-increment: rev;
  content: counter(rev, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 17px;
  font-family: var(--font-num);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--signal-ink);
}
.page-about .about-revisions__list strong {
  display: block;
  font-size: 15.5px;
  font-weight: 600;
  line-height: 1.5;
  color: var(--ink-950);
  margin-bottom: 3px;
}

/* ===== 团队（深色区） ===== */
.page-about .about-team__grid {
  display: grid;
  gap: 34px;
  align-items: center;
}
.page-about .section--ink .section-head__index {
  color: var(--signal);
}
.page-about .section--ink .section-head__title {
  color: var(--paper-100);
}
.page-about .section--ink .section-head__lead {
  color: rgba(246, 242, 233, 0.7);
}
.page-about .about-team__copy .section-head__index,
.page-about .about-team__copy .section-head__title,
.page-about .about-team__copy .section-head__lead {
  margin-left: 0;
}
.page-about .about-team__copy .section-head__title {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(26px, 4.4vw, 38px);
  line-height: 1.15;
  letter-spacing: -0.015em;
  margin: 0 0 14px;
}
.page-about .about-team__copy .section-head__lead {
  font-size: 15.5px;
  line-height: 1.9;
  margin: 0;
  max-width: 46ch;
}

.page-about .about-team__figure {
  margin: 0;
}
.page-about .about-team__figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--about-hairline);
  background: rgba(18, 40, 60, 0.6);
}
.page-about .about-team__figcap {
  margin-top: 12px;
  font-size: 12.5px;
  line-height: 1.65;
  color: rgba(246, 242, 233, 0.6);
}

.page-about .about-team__groups {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin-top: 46px;
  background: var(--about-hairline);
  border: 1px solid var(--about-hairline);
}
.page-about .about-team__group {
  background: var(--ink-900, #0D1B28);
  padding: 26px 22px 30px;
}
.page-about .about-team__group-num {
  font-family: var(--font-num);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--signal);
  margin: 0 0 14px;
}
.page-about .about-team__group-name {
  font-family: var(--font-head);
  font-size: 19px;
  font-weight: 700;
  line-height: 1.35;
  color: var(--paper-100);
  margin: 0 0 10px;
}
.page-about .about-team__group-text {
  font-size: 14.5px;
  line-height: 1.9;
  color: rgba(246, 242, 233, 0.68);
  margin: 0;
}

.page-about .about-team__note {
  margin: 34px 0 0;
  font-size: 14.5px;
  line-height: 1.9;
  color: rgba(246, 242, 233, 0.72);
  max-width: 66ch;
}
.page-about .about-team__note .about-link {
  color: var(--signal);
  border-bottom-color: rgba(235, 90, 22, 0.5);
}
.page-about .about-team__note .about-link:hover {
  color: var(--paper-100);
  border-bottom-color: var(--paper-100);
}

/* ===== 访问分布 ===== */
.page-about .about-reach__figure {
  margin: 34px 0 0;
}
.page-about .about-reach__figure img {
  display: block;
  width: 100%;
  height: auto;
  border: var(--line);
  background: var(--paper-200);
}
.page-about .about-reach__figcap {
  margin-top: 12px;
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--ink-600);
}
.page-about .about-reach__stats {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  margin-top: 32px;
  border-top: var(--line);
  border-left: var(--line);
}
.page-about .about-reach__stat {
  border-right: var(--line);
  border-bottom: var(--line);
  padding: 20px 18px 22px;
}
.page-about .about-reach__stat-value {
  display: block;
  font-family: var(--font-num);
  font-size: clamp(26px, 4.6vw, 34px);
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--ink-950);
}
.page-about .about-reach__stat:nth-child(2) .about-reach__stat-value {
  color: var(--signal-ink);
}
.page-about .about-reach__stat-label {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--ink-600);
}
.page-about .about-reach__note {
  margin: 26px 0 0;
  font-size: 14.5px;
  line-height: 1.9;
  color: var(--ink-600);
  max-width: 66ch;
}

/* ===== 下一阶段 ===== */
.page-about .about-next__list {
  list-style: none;
  margin: 34px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--silver-200);
  border: var(--line);
}
.page-about .about-next__item {
  background: var(--paper-100);
  padding: 26px 22px 30px;
}
.page-about .about-next__num {
  font-family: var(--font-num);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--signal-ink);
  margin: 0 0 14px;
}
.page-about .about-next__title {
  font-family: var(--font-head);
  font-size: 19px;
  font-weight: 700;
  line-height: 1.35;
  color: var(--ink-950);
  margin: 0 0 10px;
}
.page-about .about-next__text {
  font-size: 14.5px;
  line-height: 1.9;
  color: var(--ink-600);
  margin: 0;
}
.page-about .about-next__cta {
  margin: 30px 0 0;
  font-size: 15px;
  line-height: 1.9;
  color: var(--ink-600);
}

/* ===== 响应式 ===== */
@media (max-width: 519px) {
  .page-about .about-intro__facts {
    grid-template-columns: minmax(0, 1fr);
  }
}

@media (min-width: 620px) {
  .page-about .about-reach__stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .about-versions {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: 56px;
  }
  .page-about .about-team__groups {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .about-next__list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .page-about .about-intro__grid {
    grid-template-columns: minmax(0, 1fr) 340px;
    gap: 60px;
    align-items: start;
  }
  .page-about .about-intro__figure {
    margin-top: 6px;
  }

  .page-about .about-phases {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: 60px;
    align-items: start;
  }
  .page-about .about-phases__rail {
    position: sticky;
    top: calc(var(--header-h) + 28px);
  }
  .page-about .about-phase-panel {
    padding: 6px 0 0;
  }

  .page-about .about-revisions {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    gap: 64px;
    align-items: start;
  }

  .page-about .about-team__grid {
    grid-template-columns: minmax(0, 1fr) 360px;
    gap: 64px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-phase-btn,
  .page-about .about-version__num,
  .page-about .about-link {
    transition: none;
  }
}

.page-about {
  --ink-900: transparent;
}