.page-about {
  --about-toc: 230px;
  --about-gap: clamp(20px, 3vw, 40px);
  color: var(--ink);
  background: var(--snow);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding: clamp(22px, 4vw, 42px) 0 clamp(30px, 5vw, 62px);
  background: linear-gradient(180deg, var(--snow) 0%, var(--ice-pale) 100%);
  border-bottom: 1px solid var(--line);
  overflow: hidden;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(
    90deg,
    rgba(44, 122, 148, 0.075) 0 1px,
    transparent 1px 78px
  );
  pointer-events: none;
}

.page-about .about-hero .container {
  position: relative;
  z-index: 1;
}

.page-about .about-hero .breadcrumb {
  margin-bottom: clamp(22px, 4vw, 40px);
}

.page-about .about-hero__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(20px, 3vw, 36px);
}

.page-about .about-hero__title {
  margin: 10px 0 0;
  font-size: clamp(40px, 7vw, 96px);
  font-weight: 900;
  line-height: 1.02;
  letter-spacing: -0.03em;
}

.page-about .about-hero__title em {
  font-style: normal;
  color: var(--maple);
}

.page-about .about-hero .eyebrow {
  color: var(--ice);
}

.page-about .about-hero__aside {
  border-left: 2px solid var(--ice);
  padding-left: clamp(16px, 2vw, 26px);
}

.page-about .about-hero__aside .lede {
  margin: 0;
  font-size: clamp(16px, 1.9vw, 19px);
  line-height: 1.85;
  color: var(--ink);
}

/* ---------- 首图 ---------- */
.page-about .about-figure {
  margin: clamp(30px, 5vw, 56px) 0 0;
}

.page-about .about-figure .figure__frame {
  border: 1px solid var(--line);
  background: var(--paper);
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.page-about .about-figure .figure__caption {
  margin-top: 10px;
  font-size: 12.5px;
  line-height: 1.7;
  color: var(--slate);
  letter-spacing: 0.02em;
}

/* ---------- 正文骨架 ---------- */
.page-about .about-body__inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(26px, 4vw, 48px);
  padding-top: clamp(36px, 6vw, 76px);
  padding-bottom: clamp(44px, 7vw, 92px);
}

/* ---------- 侧栏目录 ---------- */
.page-about .about-toc {
  border-top: 1px solid var(--line-strong);
  padding-top: 14px;
}

.page-about .about-toc .toc__title {
  margin: 0 0 10px;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.18em;
  color: var(--slate);
  text-transform: uppercase;
}

.page-about .about-toc .toc__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2px 10px;
}

.page-about .about-toc .toc__link {
  display: block;
  padding: 6px 0 6px 11px;
  border-left: 1px solid var(--line);
  font-size: 12.5px;
  line-height: 1.55;
  color: var(--slate);
  text-decoration: none;
  transition: color 0.2s ease, border-color 0.2s ease;
}

.page-about .about-toc .toc__link:hover,
.page-about .about-toc .toc__link:focus-visible {
  color: var(--ice);
  border-left-color: var(--ice);
}

.page-about .about-toc .toc__link[aria-current="true"] {
  color: var(--maple);
  border-left-color: var(--maple);
  font-weight: 700;
}

/* ---------- 章节 ---------- */
.page-about .about-flow {
  min-width: 0;
}

.page-about .about-chapter {
  padding-bottom: clamp(40px, 6vw, 76px);
}

.page-about .about-chapter + .about-chapter {
  border-top: 1px solid var(--line);
  padding-top: clamp(30px, 5vw, 54px);
}

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

.page-about .about-chapter__head {
  display: grid;
  grid-template-columns: var(--num-col) minmax(0, 1fr);
  gap: 0 16px;
  align-items: start;
}

.page-about .about-chapter__num {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--gold-ink);
  border-top: 2px solid var(--gold);
  padding-top: 7px;
}

.page-about .about-chapter__title {
  margin: 0;
  font-size: clamp(24px, 3.4vw, 38px);
  font-weight: 900;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.page-about .about-chapter__body {
  margin-top: clamp(16px, 2.5vw, 26px);
}

.page-about .about-chapter__body > p {
  margin: 0 0 16px;
  font-size: 17px;
  line-height: 1.85;
  max-width: 62ch;
}

.page-about .about-chapter__body a {
  color: var(--ice);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}

.page-about .about-chapter__body a:hover {
  color: var(--maple-hot);
}

.page-about .about-cols {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0 var(--about-gap);
}

.page-about .about-cols p {
  margin: 0 0 16px;
  font-size: 17px;
  line-height: 1.85;
}

.page-about .about-note {
  border-left: 2px solid var(--gold);
  padding: 2px 0 2px 16px;
  font-size: 14.5px !important;
  line-height: 1.8 !important;
  color: var(--slate);
}

.page-about .about-small {
  font-size: 14px !important;
  line-height: 1.75 !important;
  color: var(--slate);
  margin: 0 !important;
}

.page-about .about-quote {
  margin: clamp(20px, 3vw, 32px) 0 0;
  padding: clamp(20px, 3vw, 30px) clamp(20px, 3vw, 34px);
  background: var(--deep);
  color: var(--snow);
  border-left: 6px solid var(--maple);
  font-size: clamp(16px, 2.1vw, 20px);
  font-weight: 500;
  line-height: 1.75;
  letter-spacing: 0.01em;
}

/* ---------- 三阶段 ---------- */
.page-about .about-phases {
  list-style: none;
  margin: clamp(22px, 3vw, 34px) 0 0;
  padding: 0;
}

.page-about .about-phase {
  display: grid;
  grid-template-columns: var(--num-col) minmax(0, 1fr);
  gap: 0 16px;
  padding: 20px 0;
  border-top: 1px solid var(--line);
  transition: background-color 0.2s ease;
}

.page-about .about-phase:last-child {
  border-bottom: 1px solid var(--line);
}

.page-about .about-phase:hover {
  background: rgba(221, 239, 244, 0.5);
}

.page-about .about-phase__num {
  font-family: var(--font-mono);
  font-size: 24px;
  font-weight: 700;
  color: var(--maple);
  line-height: 1.3;
}

.page-about .about-phase__title {
  margin: 0 0 8px;
  font-size: 18px;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.page-about .about-phase p {
  margin: 0 0 10px;
  font-size: 16px;
  line-height: 1.8;
}

.page-about .about-phase__link {
  margin: 0 !important;
  font-size: 14px !important;
}

/* ---------- 版本条目 ---------- */
.page-about .about-versions {
  list-style: none;
  margin: clamp(20px, 3vw, 30px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 10px;
}

.page-about .about-version {
  padding: 14px 16px;
  background: var(--paper);
  border: 1px solid var(--line);
  transition: border-color 0.2s ease, background-color 0.2s ease, transform 0.2s ease;
}

.page-about .about-version:hover {
  border-color: var(--ice);
  background: var(--snow);
  transform: translateX(3px);
}

.page-about .about-version__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 4px 12px;
  margin: 0 0 5px;
}

.page-about .about-version__name {
  font-size: 15px;
  font-weight: 700;
}

.page-about .about-version__code {
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 700;
  color: var(--maple);
  letter-spacing: 0.04em;
}

.page-about .about-version__note {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--slate);
}

/* ---------- 规模数字 ---------- */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line-strong);
  border: 1px solid var(--line-strong);
  margin-bottom: clamp(20px, 3vw, 28px);
}

.page-about .about-stat {
  background: var(--paper);
  padding: 18px 16px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.page-about .about-stat__num {
  font-family: var(--font-mono);
  font-size: clamp(28px, 4.4vw, 42px);
  font-weight: 700;
  line-height: 1;
  color: var(--ice);
}

.page-about .about-stat__label {
  font-size: 12.5px;
  letter-spacing: 0.04em;
  color: var(--slate);
}

/* ---------- 分类清单 ---------- */
.page-about .about-cats {
  list-style: none;
  margin: 14px 0 20px;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px 16px;
}

.page-about .about-cats li {
  position: relative;
  padding-left: 16px;
  font-size: 15.5px;
  line-height: 1.7;
  color: var(--ink);
}

.page-about .about-cats li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 6px;
  height: 6px;
  background: var(--gold);
}

/* ---------- 下一条路径 ---------- */
.page-about .about-next__routes {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 10px;
  margin: clamp(20px, 3vw, 28px) 0 18px;
}

.page-about .about-route {
  display: grid;
  gap: 5px;
  padding: 16px 18px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-left: 4px solid var(--ice);
  text-decoration: none !important;
  transition: border-left-color 0.2s ease, background-color 0.2s ease, transform 0.2s ease;
}

.page-about .about-route:hover {
  border-left-color: var(--maple);
  background: var(--ice-pale);
  transform: translateY(-2px);
}

.page-about .about-route__tag {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.16em;
  color: var(--gold-ink);
  text-transform: uppercase;
}

.page-about .about-route__title {
  font-size: 17px;
  font-weight: 700;
  line-height: 1.4;
  color: var(--ink);
}

.page-about .about-route__meta {
  font-size: 13px;
  line-height: 1.6;
  color: var(--slate);
}

/* ---------- 断点 ---------- */
@media (min-width: 760px) {
  .page-about .about-hero__grid {
    grid-template-columns: 7fr 5fr;
    align-items: end;
  }

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

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

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

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

@media (min-width: 960px) {
  .page-about .about-body__inner {
    grid-template-columns: var(--about-toc) minmax(0, 1fr);
    gap: clamp(30px, 4vw, 60px);
  }

  .page-about .about-toc {
    position: sticky;
    top: 112px;
    align-self: start;
  }

  .page-about .about-toc .toc__list {
    grid-template-columns: minmax(0, 1fr);
  }

  .page-about .about-chapter__body {
    padding-left: calc(var(--num-col) + 16px);
  }

  .page-about .about-chapter__body > p,
  .page-about .about-cols p {
    max-width: 68ch;
  }
}
</br>