.page-about {
  --ab-rule: var(--jn-line);
  --ab-measure: 42em;
}

.page-about .jn-crumbs {
  margin-block: 20px 0;
}

.page-about a:focus-visible,
.page-about .ab-tier:focus-visible {
  outline: 2px solid var(--jn-lake);
  outline-offset: 2px;
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  display: grid;
  gap: 30px;
  padding-block: 26px 54px;
}

.page-about .ab-hero__text {
  max-width: 680px;
}

.page-about .ab-hero__text .jn-lead {
  margin: 14px 0 0;
  max-width: 38em;
}

.page-about .ab-hero__stats {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--ab-rule);
  border: 1px solid var(--ab-rule);
}

.page-about .ab-hero__stats li {
  background: var(--jn-paper-3);
  padding: 12px 14px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.page-about .ab-stat__num {
  font-family: var(--jn-mono-font);
  font-variant-numeric: tabular-nums;
  font-size: 26px;
  font-weight: 700;
  line-height: 1.15;
  color: var(--jn-lake-deep);
}

.page-about .ab-stat__label {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--jn-graphite);
}

.page-about .ab-hero__figure {
  margin: 0;
}

.page-about .ab-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  border: 1px solid var(--ab-rule);
}

.page-about .ab-hero__figure figcaption {
  margin-top: 10px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--jn-graphite);
}

/* ---------- 主体：阶段导航 + 长文 ---------- */
.page-about .ab-body {
  display: grid;
  gap: 34px;
  padding-block: 0 76px;
}

.page-about .ab-rail {
  border-top: 3px solid var(--jn-gold);
  padding-top: 14px;
}

.page-about .ab-rail__list {
  list-style: none;
  margin: 12px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
}

.page-about .ab-rail__list a {
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  font-size: 14px;
  color: var(--jn-night);
  text-decoration: none;
  border-bottom: 1px solid var(--ab-rule);
  padding-bottom: 2px;
}

.page-about .ab-rail__list a:hover {
  color: var(--jn-lake);
  border-bottom-color: var(--jn-lake);
}

.page-about .ab-rail__list .jn-num {
  font-family: var(--jn-mono-font);
  font-size: 12px;
  color: var(--jn-gold);
}

.page-about .ab-rail__note {
  margin: 14px 0 0;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--jn-graphite);
}

/* ---------- 章节骨架 ---------- */
.page-about .ab-section {
  border-top: 1px solid var(--ab-rule);
  padding-block: 34px 40px;
}

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

.page-about .ab-section__head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  column-gap: 16px;
  row-gap: 8px;
  margin-bottom: 24px;
}

.page-about .ab-section__no {
  font-family: var(--jn-mono-font);
  font-variant-numeric: tabular-nums;
  font-size: 22px;
  font-weight: 700;
  line-height: 1;
  padding-top: 6px;
  color: var(--jn-gold);
}

.page-about .ab-section__head .jn-h2 {
  grid-column: 2;
  margin: 0;
}

.page-about .ab-section__lead {
  grid-column: 2;
  margin: 0;
  max-width: 40em;
  font-size: 15px;
  line-height: 1.72;
  color: var(--jn-graphite);
}

.page-about .ab-section__body > p {
  margin: 0 0 16px;
  max-width: var(--ab-measure);
  font-size: 16.5px;
  line-height: 1.82;
  color: var(--jn-night);
}

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

/* ---------- 分档方法 ---------- */
.page-about .ab-method {
  display: grid;
  gap: 22px;
  margin-bottom: 26px;
}

.page-about .ab-method__chart {
  background: var(--jn-paper-2);
  border: 1px solid var(--ab-rule);
  padding: 14px;
}

.page-about .ab-method__chart svg {
  display: block;
  width: 100%;
  height: auto;
}

.page-about .ab-method__text p {
  margin: 0 0 14px;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--jn-night);
}

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

.page-about .ab-tiers {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--ab-rule);
  border: 1px solid var(--ab-rule);
}

.page-about .ab-tier {
  background: var(--jn-paper-3);
  padding: 18px 18px 16px;
  transition: background 0.25s var(--jn-ease);
}

.page-about .ab-tier:hover,
.page-about .ab-tier:focus {
  background: var(--jn-paper-2);
}

.page-about .ab-tier__no {
  font-family: var(--jn-mono-font);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--jn-gold);
}

.page-about .ab-tier .jn-h3 {
  margin: 6px 0 8px;
}

.page-about .ab-tier__desc {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--jn-night);
}

.page-about .ab-tier__note {
  margin: 0;
  padding: 0 10px;
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  border-left: 3px solid var(--jn-gold);
  background: var(--jn-paper-2);
  font-size: 13px;
  line-height: 1.65;
  color: var(--jn-lake-deep);
  transition: max-height 0.35s var(--jn-ease), opacity 0.25s var(--jn-ease), padding 0.35s var(--jn-ease);
}

.page-about .ab-tier:hover .ab-tier__note,
.page-about .ab-tier:focus-within .ab-tier__note,
.page-about .ab-tier:focus .ab-tier__note {
  max-height: 160px;
  opacity: 1;
  padding: 10px;
}

.page-about .ab-figure {
  margin: 30px 0 0;
}

.page-about .ab-figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 14 / 9;
  object-fit: cover;
  border: 1px solid var(--ab-rule);
}

.page-about .ab-figure figcaption {
  margin-top: 10px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--jn-graphite);
}

/* ---------- 团队 ---------- */
.page-about .ab-team {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 26px;
}

.page-about .ab-team__item {
  display: grid;
  justify-items: start;
  gap: 10px;
}

.page-about .ab-team__item .jn-h3 {
  margin: 0;
}

.page-about .ab-team__item p {
  margin: 0;
  max-width: 34em;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--jn-graphite);
}

.page-about .ab-ring {
  --p: 0%;
  --c: var(--jn-lake);
  position: relative;
  display: grid;
  place-items: center;
  width: 96px;
  height: 96px;
  border-radius: 50%;
  background: conic-gradient(from -90deg, var(--c) var(--p), var(--jn-line) var(--p));
}

.page-about .ab-ring::after {
  content: "";
  position: absolute;
  inset: 11px;
  border-radius: 50%;
  background: var(--jn-paper-3);
}

.page-about .ab-ring__num {
  position: relative;
  z-index: 1;
  font-family: var(--jn-mono-font);
  font-variant-numeric: tabular-nums;
  font-size: 24px;
  font-weight: 700;
  color: var(--jn-night);
}

.page-about .ab-fold {
  border-top: 1px solid var(--ab-rule);
  margin-top: 26px;
}

.page-about .ab-fold:last-of-type {
  border-bottom: 1px solid var(--ab-rule);
}

.page-about .ab-fold .jn-fold__summary {
  cursor: pointer;
  padding: 14px 0;
  font-size: 15.5px;
  font-weight: 600;
  color: var(--jn-night);
}

.page-about .ab-fold .jn-fold__summary:hover {
  color: var(--jn-lake);
}

.page-about .ab-fold .jn-fold__body {
  padding: 0 0 18px;
}

.page-about .ab-fold .jn-fold__body p {
  margin: 0 0 12px;
  max-width: var(--ab-measure);
  font-size: 15px;
  line-height: 1.78;
  color: var(--jn-graphite);
}

.page-about .ab-fold .jn-fold__body p:last-child {
  margin-bottom: 0;
}

/* ---------- 互校主题带 ---------- */
.page-about .ab-cross {
  border-top: 0;
  background: var(--jn-lake);
  padding: 30px 22px;
}

.page-about .ab-cross .jn-h2 {
  color: var(--jn-paper);
}

.page-about .ab-cross .ab-section__lead {
  color: var(--jn-lake-light);
}

.page-about .ab-cross .ab-section__body p {
  max-width: var(--ab-measure);
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.8;
  color: var(--jn-paper-2);
}

.page-about .ab-cross .ab-section__body p:last-of-type {
  margin-bottom: 0;
}

.page-about .ab-cross__list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: rgba(244, 239, 227, 0.25);
  border: 1px solid rgba(244, 239, 227, 0.25);
}

.page-about .ab-cross__list li {
  display: flex;
  align-items: baseline;
  gap: 10px;
  background: var(--jn-lake-deep);
  padding: 12px 14px;
  font-size: 14.5px;
  line-height: 1.65;
  color: var(--jn-paper-2);
}

.page-about .ab-cross__list .jn-num {
  font-family: var(--jn-mono-font);
  font-size: 18px;
  font-weight: 700;
  color: var(--jn-gold);
}

/* ---------- 年度册 ---------- */
.page-about .ab-series {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--ab-rule);
  border: 1px solid var(--ab-rule);
}

.page-about .ab-series__item {
  background: var(--jn-paper-3);
  padding: 18px;
}

.page-about .ab-series__item .jn-label {
  display: block;
  margin: 0 0 6px;
  color: var(--jn-gold);
}

.page-about .ab-series__item .jn-h3 {
  margin: 0 0 8px;
}

.page-about .ab-series__item p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--jn-graphite);
}

.page-about .ab-issues {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--ab-rule);
}

.page-about .ab-issues li {
  display: flex;
  align-items: baseline;
  gap: 10px;
  background: var(--jn-paper-2);
  padding: 10px 12px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--jn-night);
}

.page-about .ab-issues .jn-num {
  font-family: var(--jn-mono-font);
  font-size: 12px;
  white-space: nowrap;
  color: var(--jn-lake-deep);
}

/* ---------- 时间轴 ---------- */
.page-about .ab-timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}

.page-about .ab-timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 10px;
  bottom: 10px;
  width: 1px;
  background: var(--ab-rule);
}

.page-about .ab-timeline__item {
  position: relative;
  padding: 0 0 30px 34px;
}

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

.page-about .ab-timeline__dot {
  position: absolute;
  left: 0;
  top: 8px;
  width: 15px;
  height: 15px;
  background: var(--jn-paper);
  border: 1px solid var(--jn-lake);
}

.page-about .ab-timeline__item:last-child .ab-timeline__dot {
  background: var(--jn-lake);
}

.page-about .ab-timeline__item .jn-label {
  margin: 0 0 4px;
  color: var(--jn-gold);
}

.page-about .ab-timeline__item .jn-h3 {
  margin: 0 0 8px;
}

.page-about .ab-timeline__item p {
  margin: 0;
  max-width: 40em;
  font-size: 15px;
  line-height: 1.78;
  color: var(--jn-graphite);
}

/* ---------- 入口列表 ---------- */
.page-about .ab-next__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--ab-rule);
  border: 1px solid var(--ab-rule);
}

.page-about .ab-next__list a {
  display: grid;
  gap: 4px;
  padding: 16px 18px;
  background: var(--jn-paper-3);
  color: inherit;
  text-decoration: none;
  transition: background 0.25s var(--jn-ease);
}

.page-about .ab-next__list a:hover {
  background: var(--jn-paper-2);
}

.page-about .ab-next__t {
  font-size: 16px;
  font-weight: 700;
  color: var(--jn-lake-deep);
}

.page-about .ab-next__d {
  font-size: 13.5px;
  line-height: 1.65;
  color: var(--jn-graphite);
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .ab-tiers {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .ab-method {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    align-items: start;
    gap: 26px;
  }

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

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

@media (min-width: 900px) {
  .page-about .ab-hero {
    grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.92fr);
    gap: clamp(32px, 4vw, 64px);
    align-items: start;
    padding-block: 36px 72px;
  }

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

  .page-about .ab-team {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1px;
    background: var(--ab-rule);
    border: 1px solid var(--ab-rule);
  }

  .page-about .ab-team__item {
    background: var(--jn-paper-3);
    padding: 22px 20px;
  }

  .page-about .ab-cross {
    padding: 36px 30px;
  }
}

@media (min-width: 1040px) {
  .page-about .ab-body {
    grid-template-columns: 210px minmax(0, 1fr);
    gap: clamp(36px, 5vw, 80px);
  }

  .page-about .ab-rail {
    position: sticky;
    top: 104px;
    align-self: start;
  }

  .page-about .ab-rail__list {
    flex-direction: column;
    gap: 0;
  }

  .page-about .ab-rail__list li {
    border-bottom: 1px solid var(--ab-rule);
  }

  .page-about .ab-rail__list a {
    display: flex;
    width: 100%;
    padding: 9px 0;
    border-bottom: 0;
  }
}

@media (min-width: 1180px) {
  .page-about .ab-tiers {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (hover: none) {
  .page-about .ab-tier__note {
    max-height: none;
    opacity: 1;
    padding: 10px;
  }
}
<<<END>>>