.page-about {
  --about-gap: clamp(20px, 3vw, 40px);
  color: var(--paper);
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumb {
  padding-top: clamp(88px, 11vh, 132px);
  padding-bottom: 16px;
}
.page-about .breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
}
.page-about .breadcrumb a {
  color: var(--steel);
  text-decoration: none;
}
.page-about .breadcrumb a:hover {
  color: var(--fox-warm);
}
.page-about .breadcrumb li:not(:last-child)::after {
  content: "/";
  margin-left: 10px;
  color: var(--line-600);
}
.page-about .breadcrumb [aria-current="page"] {
  color: var(--paper);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding-bottom: clamp(28px, 4vw, 56px);
}
.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: clamp(72px, 9vh, 116px) 0 auto 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line-600) 18%, var(--line-600) 82%, transparent);
  pointer-events: none;
}
.page-about .about-hero__grid {
  display: grid;
  gap: clamp(22px, 3vw, 36px);
}
.page-about .about-eyebrow {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--fox);
}
.page-about .about-hero h1 {
  margin: 0 0 18px;
  font-family: var(--font-display);
  font-size: clamp(36px, 7.6vw, 74px);
  line-height: 1.02;
  letter-spacing: 0.005em;
  color: var(--paper);
  text-wrap: balance;
}
.page-about .about-hero__sub {
  margin: 0 0 26px;
  max-width: 60ch;
  font-size: clamp(15px, 1.7vw, 17px);
  line-height: 1.85;
  color: var(--steel);
}
.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}
.page-about .about-hero__meta {
  align-self: end;
  padding-top: 16px;
  border-top: 1px solid var(--line-600);
}
.page-about .about-hero__meta dl {
  margin: 0;
}
.page-about .about-meta-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  padding: 10px 0;
  border-bottom: 1px solid var(--line-400);
}
.page-about .about-meta-row dt {
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--steel);
}
.page-about .about-meta-row dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--amber);
}
.page-about .about-hero__frame {
  margin: 0;
}

/* ---------- 图片 ---------- */
.page-about .about-figure {
  margin: 0;
}
.page-about .about-figure figcaption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--steel);
}
.page-about .media-frame img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
}

/* ---------- 主体骨架 ---------- */
.page-about .about-shell {
  display: grid;
  gap: clamp(26px, 4vw, 52px);
  padding-block: clamp(34px, 5vw, 68px) clamp(48px, 6vw, 88px);
}
.page-about .about-toc {
  align-self: start;
}
.page-about .about-toc__title {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--steel);
}
.page-about .about-toc__list {
  display: flex;
  gap: 8px;
  margin: 0;
  padding: 0 0 6px;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: thin;
}
.page-about .about-toc__link {
  display: block;
  padding: 8px 15px;
  border: 1px solid var(--line-400);
  border-radius: var(--radius-pill);
  color: var(--steel);
  font-size: 14px;
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--fast) var(--ease), border-color var(--fast) var(--ease), background var(--fast) var(--ease);
}
.page-about .about-toc__link:hover,
.page-about .about-toc__link:focus-visible {
  color: var(--paper);
  border-color: var(--fox);
  background: var(--fox-soft);
}

/* ---------- 章节 ---------- */
.page-about .about-section {
  padding-block: clamp(28px, 4vw, 50px);
  border-top: 1px solid var(--line-400);
}
.page-about .about-section__head {
  display: grid;
  gap: 10px;
  margin-bottom: clamp(16px, 2.4vw, 30px);
}
.page-about .about-index {
  font-family: var(--font-mono);
  font-size: clamp(26px, 4vw, 40px);
  line-height: 1;
  color: var(--fox);
}
.page-about .about-section h2 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(25px, 3.6vw, 40px);
  line-height: 1.15;
  letter-spacing: 0.01em;
  color: var(--paper);
}
.page-about .about-lede {
  margin: 0 0 clamp(18px, 2.4vw, 28px);
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.85;
  color: var(--steel);
}
.page-about .about-cols {
  display: grid;
  gap: clamp(20px, 3vw, 36px);
}
.page-about .about-body-copy p {
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.85;
  color: var(--paper);
}
.page-about .about-body-copy p:last-child {
  margin-bottom: 0;
}
.page-about .about-note {
  padding: 4px 0 4px 18px;
  border-left: 2px solid var(--fox);
  font-size: 15px;
  line-height: 1.8;
  color: var(--steel);
}
.page-about .about-note p {
  margin: 0;
}
.page-about .about-note strong {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--amber);
}
.page-about .about-inline-link {
  margin: clamp(18px, 2.4vw, 28px) 0 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--steel);
}
.page-about .about-inline-link a {
  color: var(--link);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---------- 标签页 ---------- */
.page-about .about-tabs__bar {
  display: flex;
  gap: 8px;
  padding-bottom: 8px;
  overflow-x: auto;
  border-bottom: 1px solid var(--line-400);
  scrollbar-width: thin;
}
.page-about .about-tab {
  flex: 0 0 auto;
  padding: 10px 18px;
  border: 1px solid var(--line-400);
  border-radius: var(--radius-pill);
  background: transparent;
  color: var(--steel);
  font-family: var(--font-display);
  font-size: 16px;
  letter-spacing: 0.04em;
  cursor: pointer;
  transition: color var(--fast) var(--ease), border-color var(--fast) var(--ease), background var(--fast) var(--ease);
}
.page-about .about-tab:hover {
  color: var(--paper);
  border-color: var(--fox);
}
.page-about .about-tab:focus-visible {
  outline: 2px solid var(--live);
  outline-offset: 2px;
}
.page-about .about-tab[aria-selected="true"] {
  background: var(--fox);
  border-color: var(--fox);
  color: var(--ink-900);
}
.page-about .about-panel {
  padding-top: clamp(18px, 2.6vw, 30px);
}
.page-about .about-panel h3 {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-size: clamp(19px, 2.2vw, 24px);
  line-height: 1.3;
  color: var(--fox-warm);
}
.page-about .about-panel p {
  margin: 0 0 16px;
  max-width: 66ch;
  font-size: 16px;
  line-height: 1.85;
  color: var(--paper);
}
.page-about .about-panel ul {
  display: grid;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about .about-panel li {
  position: relative;
  padding-left: 20px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--steel);
}
.page-about .about-panel li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--live);
}

/* ---------- 版本时间线 ---------- */
.page-about .about-timeline {
  margin: clamp(20px, 3vw, 34px) 0 0;
  padding: 0 0 0 4px;
  list-style: none;
}
.page-about .about-tl-item {
  position: relative;
  padding: 0 0 clamp(22px, 3vw, 32px) 32px;
  border-left: 1px solid var(--line-400);
}
.page-about .about-tl-item:last-child {
  padding-bottom: 0;
  border-left-color: transparent;
}
.page-about .about-tl-item::before {
  content: "";
  position: absolute;
  left: -7px;
  top: 4px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--ink-900);
  border: 2px solid var(--line-600);
  transition: border-color var(--fast) var(--ease), background var(--fast) var(--ease), box-shadow var(--fast) var(--ease);
}
.page-about .about-tl-item:hover::before {
  border-color: var(--fox);
  background: var(--fox);
  box-shadow: 0 0 0 4px var(--fox-soft);
}
.page-about .about-tl-ver {
  display: inline-block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: 0.14em;
  color: var(--amber);
}
.page-about .about-tl-item h3 {
  margin: 0 0 6px;
  font-family: var(--font-display);
  font-size: clamp(18px, 2vw, 22px);
  color: var(--paper);
}
.page-about .about-tl-item p {
  margin: 0;
  max-width: 60ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--steel);
}

/* ---------- 步骤 ---------- */
.page-about .about-steps {
  counter-reset: about-step;
  display: grid;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about .about-steps li {
  position: relative;
  padding: 16px 18px 16px 62px;
  border: 1px solid var(--line-400);
  border-radius: var(--radius-md);
  background: var(--ink-700);
  transition: border-color var(--fast) var(--ease), transform var(--fast) var(--ease);
}
.page-about .about-steps li:hover {
  border-color: var(--fox);
  transform: translateY(-2px);
}
.page-about .about-steps li::before {
  counter-increment: about-step;
  content: counter(about-step, decimal-leading-zero);
  position: absolute;
  left: 18px;
  top: 16px;
  font-family: var(--font-mono);
  font-size: 16px;
  color: var(--fox);
}
.page-about .about-steps h3 {
  margin: 0 0 6px;
  font-family: var(--font-display);
  font-size: 18px;
  letter-spacing: 0.02em;
  color: var(--paper);
}
.page-about .about-steps p {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--steel);
}

/* ---------- 联系区 ---------- */
.page-about .about-section--last {
  border-bottom: 1px solid var(--line-400);
}
.page-about .about-cta {
  display: grid;
  gap: clamp(18px, 2.6vw, 28px);
  padding: clamp(22px, 3.6vw, 42px);
  border: 1px solid var(--line-400);
  border-radius: var(--radius-lg);
  background:
    radial-gradient(circle at 92% 8%, var(--fox-soft), transparent 58%),
    linear-gradient(140deg, var(--ink-700), var(--ink-800));
}
.page-about .about-cta__text p {
  margin: 0 0 12px;
  max-width: 64ch;
  font-size: 16px;
  line-height: 1.85;
  color: var(--paper);
}
.page-about .about-cta__note {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--live);
}
.page-about .about-contact {
  display: grid;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about .about-contact li {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line-400);
}
.page-about .about-contact__label {
  min-width: 74px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--steel);
}
.page-about .about-contact__value {
  font-family: var(--font-mono);
  font-size: 15px;
  word-break: break-word;
  color: var(--amber);
}
.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 回到顶部 ---------- */
.page-about .about-foot {
  display: flex;
  justify-content: flex-end;
  padding-top: clamp(18px, 2.4vw, 30px);
}
.page-about .about-top {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.12em;
  color: var(--steel);
  text-decoration: none;
  border-bottom: 1px solid var(--line-600);
  padding-bottom: 3px;
  transition: color var(--fast) var(--ease), border-color var(--fast) var(--ease);
}
.page-about .about-top:hover {
  color: var(--fox-warm);
  border-color: var(--fox);
}

/* ---------- 响应式 ---------- */
@media (min-width: 760px) {
  .page-about .about-section__head {
    grid-template-columns: 92px minmax(0, 1fr);
    align-items: start;
  }
  .page-about .about-steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.3fr) minmax(260px, 0.7fr);
    align-items: end;
  }
  .page-about .about-hero__frame {
    grid-column: 1 / -1;
  }
  .page-about .about-cols {
    grid-template-columns: minmax(0, 1.6fr) minmax(230px, 0.9fr);
    align-items: start;
  }
  .page-about .about-contact {
    max-width: 720px;
  }
}

@media (min-width: 1080px) {
  .page-about .about-shell {
    grid-template-columns: 208px minmax(0, 1fr);
  }
  .page-about .about-toc {
    position: sticky;
    top: 108px;
  }
  .page-about .about-toc__list {
    flex-direction: column;
    gap: 6px;
    padding-bottom: 0;
    overflow: visible;
  }
  .page-about .about-toc__link {
    border-color: transparent;
    border-left: 2px solid var(--line-400);
    border-radius: 0;
    padding: 6px 12px;
    white-space: normal;
  }
  .page-about .about-toc__link:hover,
  .page-about .about-toc__link:focus-visible {
    border-left-color: var(--fox);
    background: transparent;
    color: var(--paper);
  }
}

@media (min-width: 1180px) {
  .page-about .about-steps {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .about-steps li {
    padding: 62px 18px 20px;
  }
  .page-about .about-steps li::before {
    left: 18px;
    top: 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-tab,
  .page-about .about-toc__link,
  .page-about .about-steps li,
  .page-about .about-tl-item::before,
  .page-about .about-top {
    transition: none;
  }
  .page-about .about-steps li:hover {
    transform: none;
  }
}