.page-about {
  --about-rail-w: 236px;
  --about-tick: 11px;
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumbs {
  max-width: var(--shell-max);
  margin: 0 auto;
  padding: 16px var(--gutter) 0;
}

.page-about .about-crumbs ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: var(--step-2);
  color: var(--slate-deep);
}

.page-about .about-crumbs li {
  display: inline-flex;
  align-items: center;
}

.page-about .about-crumbs li + li::before {
  content: "/";
  color: var(--rule);
  margin-right: 8px;
}

.page-about .about-crumbs a {
  color: var(--bronze);
  text-decoration: none;
  border-bottom: 1px solid transparent;
}

.page-about .about-crumbs a:hover,
.page-about .about-crumbs a:focus-visible {
  border-bottom-color: var(--bronze);
}

/* ---------- 首屏：对角错位色块 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  margin-top: 18px;
  padding: 34px 0 52px;
  color: var(--paper-2);
  background: linear-gradient(142deg, var(--bronze-deep) 0%, #1B4F52 48%, var(--slate-deep) 100%);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 22px), 0 100%);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  top: -32%;
  right: -9%;
  width: 58%;
  height: 168%;
  background: linear-gradient(180deg, rgba(214, 154, 60, .30), rgba(34, 107, 102, 0) 78%);
  clip-path: polygon(52% 0, 100% 0, 100% 100%, 0 100%);
  pointer-events: none;
}

.page-about .about-hero__inner {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 30px;
  align-items: center;
}

.page-about .about-hero__kicker {
  display: inline-block;
  margin: 0 0 16px;
  padding-bottom: 6px;
  font-family: var(--mono);
  font-size: var(--label);
  letter-spacing: .18em;
  color: var(--amber-light);
  border-bottom: 1px solid rgba(241, 200, 127, .5);
}

.page-about .about-hero__title {
  margin: 0 0 16px;
  font-family: var(--sans);
  font-weight: 900;
  font-size: 30px;
  line-height: 1.2;
  letter-spacing: -.01em;
  color: var(--paper-2);
}

.page-about .about-hero__lead {
  max-width: 48ch;
  margin: 0 0 22px;
  font-size: var(--step0);
  line-height: 1.85;
  color: rgba(244, 239, 230, .88);
}

.page-about .about-hero__marks {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 10px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-hero__marks li {
  font-family: var(--mono);
  font-size: var(--label);
  letter-spacing: .06em;
  color: var(--amber-light);
  border: 1px solid rgba(241, 200, 127, .45);
  padding: 4px 9px;
  background: rgba(20, 64, 62, .35);
}

.page-about .about-hero__figure {
  position: relative;
  margin: 0;
  overflow: hidden;
  border: 1px solid rgba(241, 200, 127, .4);
  background: rgba(20, 64, 62, .45);
  box-shadow: 8px 8px 0 rgba(0, 0, 0, .2);
}

.page-about .about-hero__figure::after {
  content: "";
  position: absolute;
  top: 10px;
  right: 10px;
  width: 18px;
  height: 18px;
  border-top: 2px solid var(--amber);
  border-right: 2px solid var(--amber);
  pointer-events: none;
}

.page-about .about-hero__photo {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  filter: saturate(.92);
}

/* ---------- 页面主体网格 ---------- */
.page-about .about-layout {
  max-width: var(--shell-max);
  margin: 0 auto;
  padding: 38px var(--gutter) 64px;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 34px;
  align-items: start;
}

/* ---------- 左侧竖向时间轴 ---------- */
.page-about .about-rail {
  position: relative;
}

.page-about .about-rail__label {
  margin: 0 0 18px;
  padding-bottom: 9px;
  font-family: var(--serif);
  font-weight: 600;
  font-size: var(--step-1);
  letter-spacing: .06em;
  color: var(--bronze);
  border-bottom: 1px solid var(--rule);
}

.page-about .about-rail__list {
  position: relative;
  margin: 0;
  padding: 0 0 0 22px;
  list-style: none;
}

.page-about .about-rail__list::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--bronze) 0%, var(--slate) 58%, var(--rule-soft) 100%);
}

.page-about .about-rail__item {
  position: relative;
  padding-bottom: 20px;
}

.page-about .about-rail__item::before {
  content: "";
  position: absolute;
  left: -21px;
  top: 8px;
  width: var(--about-tick);
  height: var(--about-tick);
  background: var(--paper);
  border: 2px solid var(--slate);
  border-radius: 50%;
  transition: background-color .18s ease, border-color .18s ease;
}

.page-about .about-rail__item.is-lit::before,
.page-about .about-rail__item:hover::before,
.page-about .about-rail__item:focus-within::before {
  background: var(--amber);
  border-color: var(--bronze);
}

.page-about .about-rail__link {
  display: block;
  color: inherit;
  text-decoration: none;
}

.page-about .about-rail__link:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 3px;
}

.page-about .about-rail__num {
  display: block;
  margin-bottom: 2px;
  font-family: var(--mono);
  font-size: var(--label);
  letter-spacing: .14em;
  color: var(--slate);
}

.page-about .about-rail__title {
  display: block;
  font-size: var(--step-1);
  font-weight: 700;
  line-height: 1.5;
  color: var(--ink);
}

.page-about .about-rail__desc {
  display: block;
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  font-size: var(--step-2);
  line-height: 1.7;
  color: var(--slate-deep);
  transition: max-height .22s ease, opacity .22s ease, margin-top .22s ease;
}

.page-about .about-rail__item:hover .about-rail__desc,
.page-about .about-rail__item:focus-within .about-rail__desc {
  max-height: 6em;
  margin-top: 6px;
  opacity: 1;
}

/* ---------- 右侧章节 ---------- */
.page-about .about-sections {
  display: flex;
  flex-direction: column;
  gap: 48px;
  min-width: 0;
}

.page-about .about-section {
  scroll-margin-top: 96px;
}

.page-about .about-section__head {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 0 0 22px;
  padding: 11px 28px 11px 16px;
  background: var(--bronze);
  color: var(--paper-2);
  clip-path: polygon(0 0, calc(100% - 18px) 0, 100% 100%, 0 100%);
}

.page-about .about-section--amber .about-section__head {
  background: var(--amber);
  color: var(--ink);
}

.page-about .about-section--slate .about-section__head {
  background: var(--slate-deep);
  color: var(--paper-2);
}

.page-about .about-section__num {
  font-family: var(--mono);
  font-size: var(--label);
  letter-spacing: .12em;
  color: var(--amber-light);
}

.page-about .about-section--amber .about-section__num {
  color: var(--bronze-deep);
}

.page-about .about-section__title {
  margin: 0;
  font-family: var(--sans);
  font-weight: 800;
  font-size: var(--step2);
  line-height: 1.3;
  letter-spacing: -.005em;
  color: inherit;
}

.page-about .about-section__body {
  min-width: 0;
}

.page-about .about-section__body > p {
  max-width: 68ch;
  margin: 0 0 14px;
  font-size: var(--step0);
  line-height: 1.85;
  color: var(--ink);
}

.page-about .about-note {
  max-width: 68ch;
  margin: 18px 0 0;
  padding: 12px 14px;
  font-size: var(--step-1);
  line-height: 1.78;
  color: var(--slate-deep);
  background: var(--wash);
  border-left: 3px solid var(--bronze);
}

/* ---------- 数字卡片 ---------- */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  margin: 20px 0 0;
  background: var(--rule);
  border: 1px solid var(--rule);
}

.page-about .about-stats__item {
  padding: 16px 10px;
  background: var(--paper-2);
  text-align: center;
}

.page-about .about-stats__num {
  display: block;
  font-family: var(--mono);
  font-size: 28px;
  font-weight: 600;
  line-height: 1.2;
  color: var(--bronze);
}

.page-about .about-stats__label {
  display: block;
  margin-top: 6px;
  font-size: var(--step-2);
  line-height: 1.5;
  color: var(--slate-deep);
}

/* ---------- 编号三段 ---------- */
.page-about .about-code {
  display: grid;
  gap: 1px;
  margin: 20px 0 22px;
  padding: 0;
  list-style: none;
  background: var(--rule-soft);
  border: 1px solid var(--rule-soft);
}

.page-about .about-code__part {
  display: grid;
  grid-template-columns: 82px minmax(0, 1fr);
  gap: 14px;
  padding: 14px 16px;
  background: var(--paper-2);
  align-items: start;
}

.page-about .about-code__seg {
  display: block;
  padding: 5px 6px;
  font-family: var(--mono);
  font-size: 17px;
  letter-spacing: .06em;
  text-align: center;
  color: var(--bronze);
  background: var(--wash);
  border: 1px solid rgba(34, 107, 102, .24);
}

.page-about .about-code__name {
  margin: 0 0 4px;
  font-size: var(--step1);
  font-weight: 700;
  color: var(--ink);
}

.page-about .about-code__part p {
  margin: 0;
  font-size: var(--step-1);
  line-height: 1.75;
  color: var(--slate-deep);
}

/* ---------- 归档触发情形 ---------- */
.page-about .about-rules {
  counter-reset: about-rule;
  margin: 6px 0 16px;
  padding: 0;
  list-style: none;
}

.page-about .about-rules__item {
  position: relative;
  margin-bottom: 12px;
  padding-left: 34px;
}

.page-about .about-rules__item::before {
  counter-increment: about-rule;
  content: counter(about-rule, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 3px;
  padding: 0 4px;
  font-family: var(--mono);
  font-size: var(--label);
  line-height: 18px;
  color: var(--bronze);
  border: 1px solid var(--amber);
  background: var(--wash-amber);
}

.page-about .about-rules__item p {
  max-width: 66ch;
  margin: 0;
  font-size: var(--step-1);
  line-height: 1.8;
  color: var(--ink);
}

/* ---------- 图片容器 ---------- */
.page-about .about-figure {
  margin: 22px 0;
  padding: 13px;
  background: var(--paper-2);
  border: 1px solid var(--rule);
  box-shadow: var(--shadow-slab);
}

.page-about .about-figure__img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border: 1px solid var(--rule-soft);
}

.page-about .about-figure__cap {
  margin-top: 10px;
  font-size: var(--step-2);
  line-height: 1.7;
  color: var(--slate-deep);
}

/* ---------- 字段定义列表 ---------- */
.page-about .about-fields {
  margin: 0 0 20px;
  border-top: 1px solid var(--rule);
}

.page-about .about-fields__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 4px;
  padding: 13px 0;
  border-bottom: 1px solid var(--rule-soft);
}

.page-about .about-fields__row dt {
  font-size: var(--step-1);
  font-weight: 700;
  color: var(--bronze);
}

.page-about .about-fields__row dd {
  margin: 0;
  font-size: var(--step-1);
  line-height: 1.8;
  color: var(--ink);
}

/* ---------- 五个等级 ---------- */
.page-about .about-levels {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  margin: 20px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-levels__item {
  padding: 14px 16px 16px;
  background: var(--paper-2);
  border: 1px solid var(--rule);
  border-left: 4px solid var(--bronze);
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}

.page-about .about-levels__item--b { border-left-color: var(--amber); }
.page-about .about-levels__item--c { border-left-color: var(--slate); }
.page-about .about-levels__item--d { border-left-color: var(--slate-deep); }
.page-about .about-levels__item--e { border-left-color: var(--ember); }

.page-about .about-levels__item:hover {
  transform: translateY(-3px);
  border-color: var(--bronze);
  box-shadow: var(--shadow-slab);
}

.page-about .about-levels__tag {
  display: inline-block;
  padding: 3px 9px;
  font-family: var(--mono);
  font-size: var(--label);
  letter-spacing: .06em;
  color: var(--bronze-deep);
  background: var(--wash-amber);
  border: 1px solid rgba(214, 154, 60, .48);
}

.page-about .about-levels__item--d .about-levels__tag {
  color: var(--paper-2);
  background: var(--slate-deep);
  border-color: var(--slate-deep);
}

.page-about .about-levels__item--e .about-levels__tag {
  color: var(--paper-2);
  background: var(--ember);
  border-color: var(--ember);
}

.page-about .about-levels__item p {
  margin: 9px 0 0;
  font-size: var(--step-1);
  line-height: 1.75;
  color: var(--slate-deep);
}

/* ---------- 三个小组 ---------- */
.page-about .about-groups {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
  margin: 20px 0 20px;
  padding: 0;
  list-style: none;
}

.page-about .about-groups__item {
  position: relative;
  padding: 20px 16px 20px;
  background: var(--paper-2);
  border: 1px solid var(--rule);
}

.page-about .about-groups__item::before {
  content: attr(data-group-code);
  position: absolute;
  top: -1px;
  right: -1px;
  padding: 3px 9px;
  font-family: var(--mono);
  font-size: var(--label);
  letter-spacing: .1em;
  color: var(--amber-light);
  background: var(--bronze-deep);
}

.page-about .about-groups__name {
  margin: 0 0 8px;
  font-size: var(--step1);
  font-weight: 800;
  color: var(--ink);
}

.page-about .about-groups__item p {
  margin: 0;
  font-size: var(--step-1);
  line-height: 1.78;
  color: var(--slate-deep);
}

/* ---------- 页面底部速查 ---------- */
.page-about .about-check {
  margin-top: 8px;
  padding: 22px 20px;
  color: var(--paper-2);
  background: var(--bronze-deep);
  border-top: 3px solid var(--amber);
}

.page-about .about-check__lead {
  margin: 0 0 8px;
  font-family: var(--serif);
  font-weight: 600;
  font-size: var(--step2);
  color: var(--amber-light);
}

.page-about .about-check p {
  max-width: 64ch;
  margin: 0;
  font-size: var(--step-1);
  line-height: 1.8;
  color: rgba(244, 239, 230, .9);
}

.page-about .about-check a {
  color: var(--amber-light);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-check a:hover,
.page-about .about-check a:focus-visible {
  text-decoration-thickness: 2px;
}

/* ---------- 断点 ---------- */
@media (min-width: 620px) {
  .page-about .about-levels {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-fields__row {
    grid-template-columns: 124px minmax(0, 1fr);
    gap: 18px;
  }
}

@media (min-width: 720px) {
  .page-about .about-hero {
    padding: 44px 0 62px;
  }

  .page-about .about-hero__title {
    font-size: 38px;
  }

  .page-about .about-section__title {
    font-size: var(--step3);
  }

  .page-about .about-code__part {
    grid-template-columns: 96px minmax(0, 1fr);
    gap: 18px;
  }
}

@media (min-width: 900px) {
  .page-about .about-groups {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

  .page-about .about-hero__inner {
    grid-template-columns: minmax(0, 1.02fr) minmax(0, .98fr);
    gap: 46px;
  }
}

@media (min-width: 1000px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: 54px;
    padding-top: 56px;
    padding-bottom: 96px;
  }

  .page-about .about-rail {
    position: sticky;
    top: 92px;
  }
}

@media (min-width: 1100px) {
  .page-about .about-hero__title {
    font-size: 44px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail__desc,
  .page-about .about-rail__item::before,
  .page-about .about-levels__item {
    transition: none;
  }

  .page-about .about-levels__item:hover {
    transform: none;
  }
}