.page-about {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  overflow-x: hidden;
}

.page-about h2 {
  font-family: var(--font-head);
  font-weight: 900;
  font-size: clamp(1.55rem, 3.4vw, 2.35rem);
  line-height: 1.22;
  letter-spacing: -0.01em;
  margin: 6px 0 16px;
}

.page-about .hist-node,
.page-about .hist-pair {
  scroll-margin-top: 96px;
}

/* ---------- 首屏 ---------- */

.page-about .hist-hero {
  position: relative;
  background: var(--dusk);
  color: var(--paper);
  border-bottom: var(--line);
  padding: clamp(24px, 4vw, 44px) 0 0;
  overflow: hidden;
}

.page-about .hist-hero .breadcrumb {
  margin-bottom: 20px;
  color: var(--mist);
}

.page-about .hist-hero .breadcrumb a {
  color: var(--gold);
}

.page-about .hist-hero h1 {
  font-family: var(--font-head);
  font-weight: 900;
  font-size: clamp(1.9rem, 5vw, 3.5rem);
  line-height: 1.13;
  letter-spacing: -0.01em;
  margin: 0 0 18px;
  max-width: 20ch;
}

.page-about .hist-hero__lede {
  margin: 0 0 22px;
  max-width: 60ch;
  font-size: clamp(15px, 1.7vw, 17px);
  line-height: 1.85;
  color: var(--mist);
}

.page-about .hist-hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 30px;
}

.page-about .hist-hero__media {
  margin-top: 4px;
}

.page-about .hist-hero__img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  border: 2px solid var(--ink);
  box-shadow: 10px 10px 0 var(--lake);
  background: var(--ink);
}

.page-about .hist-scale {
  margin-top: 34px;
  background: rgba(21, 19, 27, 0.4);
  border-top: 2px solid var(--gold);
  border-bottom: 2px solid var(--gold);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .hist-scale__track {
  display: flex;
  min-width: max-content;
}

.page-about .hist-scale__tick {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 12px 18px;
  border-right: 1px solid rgba(169, 214, 208, 0.28);
  color: var(--paper);
  text-decoration: none;
  transition: background 160ms var(--ease), color 160ms var(--ease);
}

.page-about .hist-scale__tick:last-child {
  border-right: 0;
}

.page-about .hist-scale__tick .mono {
  font-family: var(--font-mono);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 2px;
  color: var(--paper);
  transition: color 160ms var(--ease);
}

.page-about .hist-scale__tick em {
  font-style: normal;
  font-size: 12px;
  letter-spacing: 1px;
  color: var(--mist);
  transition: color 160ms var(--ease);
}

.page-about .hist-scale__tick:hover,
.page-about .hist-scale__tick:focus-visible {
  background: var(--gold);
  outline: none;
}

.page-about .hist-scale__tick:hover .mono,
.page-about .hist-scale__tick:focus-visible .mono,
.page-about .hist-scale__tick:hover em,
.page-about .hist-scale__tick:focus-visible em {
  color: var(--ink);
}

/* ---------- 时间轴主轴 ---------- */

.page-about .hist-axis {
  background: var(--paper);
  padding: clamp(44px, 7vw, 90px) 0;
}

.page-about .hist-axis__lede {
  max-width: 58ch;
  margin: 0 0 8px;
  font-size: 0.98rem;
  line-height: 1.8;
  color: var(--rock);
}

.page-about .hist-timeline {
  position: relative;
  list-style: none;
  margin: 34px 0 0;
  padding: 0;
}

.page-about .hist-timeline::before {
  content: "";
  position: absolute;
  top: 10px;
  bottom: 10px;
  left: 10px;
  width: 3px;
  background: linear-gradient(180deg, var(--haze), var(--lake) 58%, var(--gold));
}

.page-about .hist-phase {
  position: relative;
  margin: 0 0 24px;
  padding: 9px 14px 9px 42px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 3px;
  color: var(--dusk);
  background: var(--mist);
  border: 2px solid var(--ink);
  box-shadow: var(--shadow-sm);
}

.page-about .hist-node {
  position: relative;
  padding-left: 40px;
  margin-bottom: 26px;
}

.page-about .hist-node__dot {
  position: absolute;
  left: 2px;
  top: 18px;
  width: 20px;
  height: 20px;
  background: var(--gold);
  border: 2px solid var(--ink);
  transform: rotate(45deg);
  z-index: 1;
}

.page-about .hist-card {
  background: var(--paper);
  border: 2px solid var(--ink);
  border-left: 6px solid var(--lake);
  box-shadow: var(--shadow);
  padding: 18px 18px 20px;
  transition: transform 160ms var(--ease), box-shadow 160ms var(--ease);
}

.page-about .hist-card:hover {
  transform: translate(-2px, -2px);
  box-shadow: var(--shadow-lg);
}

.page-about .hist-card--current {
  border-left-color: var(--gold);
  background: linear-gradient(180deg, var(--paper) 0%, rgba(169, 214, 208, 0.35) 100%);
}

.page-about .hist-card__head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.page-about .hist-card__ver {
  font-family: var(--font-mono);
  font-size: clamp(1.35rem, 4vw, 1.85rem);
  font-weight: 600;
  letter-spacing: 3px;
  line-height: 1;
  color: var(--dusk);
}

.page-about .hist-card__title {
  margin: 0 0 9px;
  font-family: var(--font-head);
  font-size: 1.08rem;
  font-weight: 800;
  line-height: 1.42;
}

.page-about .hist-card__body {
  margin: 0 0 14px;
  font-size: 0.94rem;
  line-height: 1.78;
  color: var(--rock);
}

.page-about .hist-card__facts {
  display: grid;
  gap: 8px;
  margin: 0;
  padding-top: 12px;
  border-top: 1px dashed rgba(108, 104, 117, 0.45);
}

.page-about .hist-card__facts > div {
  display: grid;
  grid-template-columns: 68px 1fr;
  gap: 10px;
  align-items: baseline;
}

.page-about .hist-card__facts dt {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 1px;
  color: var(--lake);
}

.page-about .hist-card__facts dd {
  margin: 0;
  font-size: 0.88rem;
  line-height: 1.62;
  color: var(--ink);
}

/* ---------- 相邻版本对照 ---------- */

.page-about .hist-versus {
  background: var(--dusk);
  color: var(--paper);
  border-top: var(--line);
  border-bottom: var(--line);
  padding: clamp(44px, 7vw, 90px) 0;
}

.page-about .hist-versus h2 {
  color: var(--paper);
}

.page-about .hist-versus__lede {
  max-width: 58ch;
  margin: 0 0 40px;
  font-size: 0.98rem;
  line-height: 1.82;
  color: var(--mist);
}

.page-about .hist-pair {
  margin-bottom: 42px;
}

.page-about .hist-pair:last-child {
  margin-bottom: 0;
}

.page-about .hist-pair__title {
  margin: 0 0 14px;
  font-family: var(--font-head);
  font-size: clamp(1.02rem, 2.2vw, 1.32rem);
  font-weight: 800;
  line-height: 1.45;
  color: var(--gold);
}

.page-about .hist-board {
  display: grid;
  gap: 3px;
  background: var(--ink);
  border: 2px solid var(--ink);
  box-shadow: var(--shadow);
}

.page-about .hist-rule {
  min-height: 6px;
  background: var(--lake);
}

.page-about .hist-side {
  padding: 20px 18px 22px;
  color: var(--paper);
}

.page-about .hist-side--prev {
  background: var(--dusk);
}

.page-about .hist-side--next {
  background: var(--lake);
}

.page-about .hist-side__label {
  display: inline-block;
  margin-bottom: 14px;
  padding: 4px 10px;
  font-family: var(--font-mono);
  font-size: 1.2rem;
  font-weight: 600;
  letter-spacing: 4px;
  line-height: 1.2;
  border: 2px solid var(--paper);
}

.page-about .hist-side ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .hist-side li {
  position: relative;
  padding-left: 20px;
  font-size: 0.92rem;
  line-height: 1.72;
}

.page-about .hist-side li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.68em;
  width: 9px;
  height: 2px;
  background: var(--gold);
}

.page-about .hist-side--prev li::before {
  background: var(--rock);
}

.page-about .hist-side li.is-changed {
  color: var(--gold);
  font-weight: 600;
}

/* ---------- 版本号怎么读 ---------- */

.page-about .hist-vernum {
  background: var(--paper);
  padding: clamp(44px, 7vw, 90px) 0;
}

.page-about .hist-vernum__lede {
  max-width: 56ch;
  margin: 0 0 30px;
  font-size: 0.98rem;
  line-height: 1.82;
  color: var(--rock);
}

.page-about .hist-anatomy {
  display: grid;
  gap: 30px;
}

.page-about .hist-anatomy__glyph {
  display: flex;
  align-items: baseline;
  justify-content: center;
  padding: 30px 14px;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(3.2rem, 15vw, 7.5rem);
  letter-spacing: 4px;
  line-height: 1;
  border: 2px solid var(--ink);
  box-shadow: var(--shadow-lg);
  background: linear-gradient(135deg, var(--paper) 0%, var(--mist) 100%);
}

.page-about .hist-anatomy__v {
  color: var(--rock);
}

.page-about .hist-anatomy__major {
  color: var(--dusk);
}

.page-about .hist-anatomy__dot {
  color: var(--gold);
}

.page-about .hist-anatomy__minor {
  color: var(--lake);
}

.page-about .hist-anatomy__notes {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 16px;
}

.page-about .hist-anatomy__notes li {
  display: grid;
  grid-template-columns: 54px 1fr;
  gap: 14px;
  align-items: start;
  padding-top: 14px;
  border-top: 2px solid var(--ink);
}

.page-about .hist-anatomy__notes li > span {
  display: block;
  padding: 5px 0;
  font-family: var(--font-mono);
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 2px;
  text-align: center;
  color: var(--gold);
  background: var(--dusk);
  border: 2px solid var(--ink);
}

.page-about .hist-anatomy__notes p {
  margin: 0;
  font-size: 0.94rem;
  line-height: 1.78;
  color: var(--ink);
}

.page-about .hist-anatomy__notes strong {
  font-weight: 800;
  color: var(--dusk);
}

.page-about .hist-vernum__tip {
  margin: 34px 0 0;
  padding: 18px 20px;
  font-size: 0.94rem;
  line-height: 1.82;
  color: var(--ink);
  background: var(--mist);
  border: 2px solid var(--ink);
  box-shadow: var(--shadow);
}

/* ---------- 归档与查找 ---------- */

.page-about .hist-archive {
  background: var(--ink);
  color: var(--paper);
  border-top: var(--line);
  padding: clamp(44px, 7vw, 90px) 0;
}

.page-about .hist-archive h2 {
  color: var(--paper);
}

.page-about .hist-archive__grid {
  display: grid;
  gap: 34px;
}

.page-about .hist-archive__intro {
  margin: 0 0 6px;
  max-width: 52ch;
  font-size: 0.96rem;
  line-height: 1.82;
  color: var(--mist);
}

.page-about .hist-archive__list {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .hist-archive__list li {
  padding: 2px 0 2px 16px;
  border-left: 4px solid var(--gold);
  font-size: 0.93rem;
  line-height: 1.76;
  color: var(--mist);
}

.page-about .hist-archive__list strong {
  color: var(--paper);
  font-weight: 700;
}

.page-about .hist-archive__figure {
  margin: 0;
}

.page-about .hist-archive__figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  border: 2px solid var(--paper);
  box-shadow: 10px 10px 0 var(--lake);
}

.page-about .hist-archive__figure figcaption {
  margin-top: 16px;
  font-size: 0.82rem;
  line-height: 1.7;
  letter-spacing: 0.5px;
  color: var(--mist);
}

/* ---------- 迭代依据 ---------- */

.page-about .hist-loop {
  background: var(--paper);
  padding: clamp(44px, 7vw, 90px) 0;
}

.page-about .hist-loop__grid {
  display: grid;
  gap: 28px;
  margin-top: 28px;
  align-items: start;
}

.page-about .hist-loop__figure {
  margin: 0;
}

.page-about .hist-loop__figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  border: 2px solid var(--ink);
  box-shadow: var(--shadow);
}

.page-about .hist-loop__steps {
  list-style: none;
  counter-reset: loop;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 18px;
}

.page-about .hist-loop__steps li {
  counter-increment: loop;
  position: relative;
  padding-left: 54px;
  font-size: 0.94rem;
  line-height: 1.78;
  color: var(--rock);
}

.page-about .hist-loop__steps li::before {
  content: "0" counter(loop);
  position: absolute;
  left: 0;
  top: 0;
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  font-family: var(--font-mono);
  font-size: 0.86rem;
  letter-spacing: 1px;
  color: var(--ink);
  background: var(--gold);
  border: 2px solid var(--ink);
  box-shadow: 3px 3px 0 var(--ink);
}

.page-about .hist-loop__steps strong {
  display: block;
  margin-bottom: 5px;
  font-family: var(--font-head);
  font-size: 1rem;
  font-weight: 800;
  color: var(--ink);
}

.page-about .hist-loop__stats {
  display: grid;
  gap: 14px;
  margin-top: 38px;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
}

.page-about .hist-stat {
  padding: 16px 18px;
  background: var(--paper);
  border: 2px solid var(--ink);
  box-shadow: var(--shadow-sm);
}

.page-about .hist-stat__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 4vw, 1.9rem);
  font-weight: 700;
  letter-spacing: 2px;
  line-height: 1.15;
  color: var(--dusk);
}

.page-about .hist-stat__label {
  display: block;
  margin-top: 7px;
  font-size: 0.86rem;
  line-height: 1.62;
  color: var(--rock);
}

/* ---------- 下一步 ---------- */

.page-about .hist-next {
  background: var(--dusk);
  color: var(--paper);
  border-top: var(--line);
  padding: clamp(44px, 7vw, 90px) 0;
}

.page-about .hist-next h2 {
  color: var(--paper);
}

.page-about .hist-next__grid {
  display: grid;
  gap: 18px;
  margin-top: 30px;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}

.page-about .hist-next__card {
  display: block;
  padding: 20px;
  color: var(--paper);
  text-decoration: none;
  background: rgba(245, 240, 230, 0.06);
  border: 2px solid rgba(245, 240, 230, 0.35);
  transition: transform 160ms var(--ease), background 160ms var(--ease), border-color 160ms var(--ease);
}

.page-about .hist-next__card:hover,
.page-about .hist-next__card:focus-visible {
  background: var(--lake);
  border-color: var(--gold);
  transform: translateY(-4px);
  outline: none;
}

.page-about .hist-next__idx {
  display: block;
  margin-bottom: 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 3px;
  color: var(--gold);
}

.page-about .hist-next__title {
  display: block;
  margin-bottom: 8px;
  font-family: var(--font-head);
  font-size: 1.06rem;
  font-weight: 800;
  line-height: 1.45;
}

.page-about .hist-next__desc {
  display: block;
  font-size: 0.89rem;
  line-height: 1.7;
  color: var(--mist);
}

/* ---------- 响应式 ---------- */

@media (min-width: 780px) {
  .page-about .hist-board {
    grid-template-columns: 1fr 6px 1fr;
    gap: 0;
  }

  .page-about .hist-rule {
    min-height: 0;
  }

  .page-about .hist-side {
    padding: 24px 24px 26px;
  }
}

@media (min-width: 860px) {
  .page-about .hist-loop__grid {
    grid-template-columns: 0.85fr 1.15fr;
    gap: 46px;
  }

  .page-about .hist-anatomy {
    grid-template-columns: minmax(260px, 1fr) 1.15fr;
    gap: 50px;
    align-items: center;
  }
}

@media (min-width: 900px) {
  .page-about .hist-timeline::before {
    left: 50%;
    margin-left: -1.5px;
  }

  .page-about .hist-phase {
    padding: 9px 18px;
    text-align: center;
  }

  .page-about .hist-node {
    width: 50%;
    padding-left: 0;
    margin-bottom: 30px;
  }

  .page-about .hist-node--left {
    padding-right: 48px;
  }

  .page-about .hist-node--right {
    padding-left: 48px;
    margin-left: 50%;
  }

  .page-about .hist-node__dot {
    top: 26px;
  }

  .page-about .hist-node--left .hist-node__dot {
    left: auto;
    right: -10px;
  }

  .page-about .hist-node--right .hist-node__dot {
    left: -10px;
  }

  .page-about .hist-archive__grid {
    grid-template-columns: 1.15fr 0.85fr;
    gap: 50px;
    align-items: start;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .hist-card,
  .page-about .hist-next__card,
  .page-about .hist-scale__tick {
    transition: none;
  }

  .page-about .hist-card:hover {
    transform: none;
  }

  .page-about .hist-next__card:hover,
  .page-about .hist-next__card:focus-visible {
    transform: none;
  }
}