.page-about {
  background-color: var(--c-ink);
  color: var(--c-white);
  font-family: var(--f-body);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding: clamp(26px, 4.5vw, 52px) 0 clamp(40px, 6vw, 76px);
  border-bottom: 1px solid var(--c-hairline);
  background-color: var(--c-ink);
  background-image:
    radial-gradient(118% 88% at 86% 0%, rgba(20, 96, 74, .58), rgba(6, 35, 28, 0) 62%),
    radial-gradient(70% 60% at 4% 100%, rgba(56, 225, 214, .09), rgba(6, 35, 28, 0) 70%);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, var(--c-hairline) 1px, transparent 1px),
    linear-gradient(to bottom, var(--c-hairline) 1px, transparent 1px);
  background-size: 88px 88px;
  opacity: .5;
}

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

.page-about .breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: rgba(242, 247, 245, .58);
}

.page-about .breadcrumbs a {
  color: rgba(242, 247, 245, .78);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--t-fast), border-color var(--t-fast);
}

.page-about .breadcrumbs a:hover,
.page-about .breadcrumbs a:focus-visible {
  color: var(--c-cyan);
  border-bottom-color: var(--c-cyan);
}

.page-about .bc-sep {
  color: rgba(242, 247, 245, .34);
}

.page-about .about-hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(26px, 4vw, 48px);
  margin-top: clamp(22px, 3vw, 36px);
}

.page-about .coord {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--c-cyan);
  margin: 0;
}

.page-about .about-hero h1 {
  font-family: var(--f-display);
  font-weight: 700;
  font-size: clamp(38px, 8vw, 76px);
  line-height: 1.02;
  letter-spacing: .03em;
  margin: 14px 0 0;
  color: var(--c-white);
}

.page-about .about-hero__lede {
  max-width: 62ch;
  margin: 18px 0 0;
  font-size: 16px;
  line-height: 1.78;
  color: rgba(242, 247, 245, .82);
}

.page-about .about-hero__stats {
  display: flex;
  flex-wrap: wrap;
  gap: 16px 30px;
  margin: 30px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-hero__stats li {
  display: flex;
  flex-direction: column;
  gap: 3px;
  min-width: 0;
}

.page-about .about-hero__stats .mono {
  font-family: var(--f-mono);
  font-size: 22px;
  line-height: 1.1;
  letter-spacing: .04em;
  color: var(--c-cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .about-hero__stats span:last-child {
  font-size: 12px;
  letter-spacing: .09em;
  color: rgba(242, 247, 245, .56);
}

.page-about .about-hero__media {
  margin: 0;
  border-radius: var(--r-lg);
  overflow: hidden;
  border: 1px solid var(--c-hairline);
  background-color: var(--c-pitch);
}

.page-about .media img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
}

.page-about .media__caption {
  font-size: 12px;
  letter-spacing: .06em;
  color: rgba(242, 247, 245, .55);
  padding: 10px 2px 0;
}

.page-about .about-ch--paper .media {
  border-color: var(--c-hairline-dark);
  background-color: rgba(16, 35, 29, .08);
}

.page-about .about-ch--paper .media__caption {
  color: rgba(16, 35, 29, .6);
}

/* ---------- 主体骨架 ---------- */
.page-about .about-main {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(22px, 4vw, 44px);
  align-items: start;
  padding-top: clamp(34px, 5vw, 72px);
  padding-bottom: clamp(46px, 7vw, 96px);
}

.page-about .axis-rail {
  display: none;
}

.page-about .about-chapters {
  display: flex;
  flex-direction: column;
  gap: clamp(26px, 4vw, 52px);
  min-width: 0;
}

/* ---------- 章节卡片 ---------- */
.page-about .about-ch {
  position: relative;
  min-width: 0;
  scroll-margin-top: 108px;
  padding: clamp(22px, 3.4vw, 44px);
  border-radius: var(--r-lg);
  border: 1px solid var(--c-hairline);
  background-color: var(--c-pitch);
  background-image: repeating-linear-gradient(135deg, rgba(242, 247, 245, .035) 0 1px, transparent 1px 14px);
}

.page-about .about-ch--paper {
  background-color: var(--c-paper);
  background-image: repeating-linear-gradient(135deg, rgba(16, 35, 29, .032) 0 1px, transparent 1px 14px);
  border-color: var(--c-hairline-dark);
  color: var(--c-ink-on-paper);
}

.page-about .about-ch--final {
  background-color: var(--c-emerald);
  background-image: repeating-linear-gradient(135deg, rgba(242, 247, 245, .05) 0 1px, transparent 1px 14px);
  border-color: rgba(56, 225, 214, .42);
}

.page-about .about-ch--paper .coord {
  color: var(--c-emerald);
}

.page-about .about-ch__title {
  font-family: var(--f-display);
  font-weight: 700;
  font-size: clamp(25px, 3.6vw, 40px);
  line-height: 1.14;
  letter-spacing: .035em;
  margin: 10px 0 0;
  color: var(--c-white);
}

.page-about .about-ch--paper .about-ch__title {
  color: var(--c-ink-on-paper);
}

.page-about .prose {
  margin: 18px 0 0;
  max-width: 74ch;
  font-size: 16px;
  line-height: 1.78;
  color: rgba(242, 247, 245, .82);
}

.page-about .about-ch--paper .prose {
  color: rgba(16, 35, 29, .8);
}

/* ---------- 旁注 ---------- */
.page-about .with-note {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(18px, 3vw, 36px);
  align-items: start;
  margin-top: 6px;
}

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

.page-about .aside-note {
  min-width: 0;
  padding-top: 14px;
  border-top: 1px solid var(--c-emerald);
  font-size: 13px;
  line-height: 1.72;
  letter-spacing: .02em;
  color: rgba(242, 247, 245, .64);
}

.page-about .aside-note p {
  margin: 0 0 10px;
}

.page-about .aside-note p:last-child {
  margin-bottom: 0;
}

.page-about .aside-note a {
  color: var(--c-amber);
  text-decoration: none;
  border-bottom: 1px solid rgba(255, 178, 94, .45);
  transition: color var(--t-fast), border-color var(--t-fast);
}

.page-about .aside-note a:hover,
.page-about .aside-note a:focus-visible {
  color: var(--c-cyan);
  border-bottom-color: var(--c-cyan);
}

.page-about .about-ch--paper .aside-note {
  border-top-color: rgba(16, 35, 29, .28);
  color: rgba(16, 35, 29, .66);
}

.page-about .about-ch--paper .aside-note .coord {
  color: var(--c-emerald);
}

.page-about .about-ch--paper .aside-note a {
  color: var(--c-emerald);
  border-bottom-color: rgba(20, 96, 74, .4);
}

/* ---------- 编号拆解盒 ---------- */
.page-about .codebox {
  margin-top: 26px;
  display: grid;
  gap: 18px;
  padding: clamp(16px, 2.4vw, 26px);
  border-radius: var(--r-md);
  border: 1px dashed var(--c-emerald);
  background-color: rgba(20, 96, 74, .22);
}

.page-about .codebox__code {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 6px 16px;
  width: 100%;
  padding: 2px 0 14px;
  border: 0;
  border-bottom: 1px solid var(--c-hairline);
  border-radius: var(--r-sm);
  background: none;
  text-align: left;
  cursor: copy;
  transition: outline-color var(--t-fast), border-color var(--t-fast);
}

.page-about .codebox__code:focus-visible {
  outline: 2px solid var(--c-cyan);
  outline-offset: 6px;
}

.page-about .codebox__code[data-copied] {
  outline: 2px solid var(--c-cyan);
  outline-offset: 6px;
  border-bottom-color: var(--c-cyan);
}

.page-about .codebox__value {
  font-family: var(--f-mono);
  font-size: clamp(20px, 3.4vw, 32px);
  font-weight: 600;
  letter-spacing: .08em;
  color: var(--c-cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .codebox__hint {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: .14em;
  color: rgba(242, 247, 245, .5);
}

.page-about .codebox__parts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px 20px;
  margin: 0;
}

.page-about .codebox__parts div {
  min-width: 0;
}

.page-about .codebox__parts dt {
  margin-bottom: 5px;
  font-size: 12px;
  letter-spacing: .09em;
  color: rgba(242, 247, 245, .58);
}

.page-about .codebox__parts dd {
  margin: 0;
  font-family: var(--f-mono);
  font-size: 16px;
  letter-spacing: .06em;
  color: var(--c-amber);
  font-variant-numeric: tabular-nums;
}

/* ---------- 标签页 ---------- */
.page-about .about-tabs {
  margin-top: 28px;
}

.page-about .tablist {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 10px;
  scrollbar-width: thin;
}

.page-about .tab {
  flex: 0 0 auto;
  padding: 9px 16px;
  border-radius: var(--r-pill);
  border: 1px solid var(--c-hairline);
  background-color: transparent;
  color: rgba(242, 247, 245, .74);
  font-family: var(--f-mono);
  font-size: 13px;
  letter-spacing: .05em;
  cursor: pointer;
  transition: background-color var(--t-fast), color var(--t-fast), border-color var(--t-fast);
}

.page-about .tab:hover,
.page-about .tab:focus-visible {
  border-color: var(--c-amber);
  color: var(--c-white);
}

.page-about .tab[aria-selected="true"] {
  background-color: var(--c-signal);
  border-color: var(--c-signal);
  color: #200D02;
  font-weight: 600;
}

.page-about .tabpanel {
  margin-top: 18px;
  padding: clamp(16px, 2.4vw, 24px);
  border-radius: var(--r-md);
  border: 1px solid var(--c-emerald);
  background-color: rgba(6, 35, 28, .5);
}

.page-about .tabpanel + .tabpanel {
  margin-top: 10px;
}

.page-about .panel__title {
  font-family: var(--f-display);
  font-size: 18px;
  letter-spacing: .06em;
  margin: 0;
  color: var(--c-white);
}

.page-about .panel__text {
  margin: 10px 0 0;
  font-size: 15px;
  line-height: 1.75;
  color: rgba(242, 247, 245, .78);
}

/* ---------- 工序流程 ---------- */
.page-about .steps {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .steps__item {
  position: relative;
  padding: 16px 18px 18px 62px;
  border-radius: var(--r-md);
  border: 1px solid rgba(255, 255, 255, .1);
  background-color: rgba(255, 255, 255, .05);
}

.page-about .about-ch--paper .steps__item {
  background-color: rgba(255, 255, 255, .72);
  border-color: rgba(16, 35, 29, .14);
}

.page-about .steps__num {
  position: absolute;
  left: 18px;
  top: 17px;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--c-cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .about-ch--paper .steps__num {
  color: var(--c-emerald);
}

.page-about .steps__title {
  font-family: var(--f-display);
  font-size: 19px;
  letter-spacing: .06em;
  margin: 0;
  color: var(--c-white);
}

.page-about .about-ch--paper .steps__title {
  color: var(--c-ink-on-paper);
}

.page-about .steps__text {
  margin: 8px 0 0;
  font-size: 15px;
  line-height: 1.75;
  color: rgba(242, 247, 245, .78);
}

.page-about .about-ch--paper .steps__text {
  color: rgba(16, 35, 29, .78);
}

.page-about .steps__media {
  list-style: none;
  margin: 4px 0;
}

.page-about .about-steps__media,
.page-about .about-archive__media {
  margin: 0;
  border-radius: var(--r-md);
  overflow: hidden;
  border: 1px solid var(--c-hairline-dark);
}

.page-about .about-steps__media img {
  aspect-ratio: 10 / 7;
  object-fit: cover;
}

.page-about .about-archive__media {
  margin-top: 26px;
  border-color: var(--c-hairline);
  background-color: var(--c-emerald);
}

.page-about .about-archive__media img {
  aspect-ratio: 2 / 1;
  object-fit: cover;
}

/* ---------- 版本时间线 ---------- */
.page-about .timeline {
  position: relative;
  list-style: none;
  margin: 28px 0 0;
  padding: 0 0 0 30px;
  display: grid;
  gap: 24px;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  border-radius: 2px;
  background-image: linear-gradient(180deg, var(--c-cyan), var(--c-emerald) 58%, rgba(20, 96, 74, 0));
}

.page-about .timeline__item {
  position: relative;
  min-width: 0;
}

.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: -30px;
  top: 6px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background-color: var(--c-ink);
  border: 2px solid var(--c-cyan);
  box-shadow: 0 0 0 4px rgba(56, 225, 214, .13);
}

.page-about .timeline__stage {
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--c-cyan);
  margin: 0;
  font-variant-numeric: tabular-nums;
}

.page-about .timeline__title {
  font-family: var(--f-display);
  font-size: 21px;
  letter-spacing: .05em;
  margin: 7px 0 0;
  color: var(--c-white);
}

.page-about .timeline__text {
  margin: 8px 0 0;
  max-width: 70ch;
  font-size: 15px;
  line-height: 1.75;
  color: rgba(242, 247, 245, .78);
}

/* ---------- 边界条目 ---------- */
.page-about .limits {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .limits__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 14px;
  padding: 15px 18px;
  border-radius: var(--r-md);
  border-left: 3px solid var(--c-alert);
  background-color: rgba(226, 59, 59, .1);
}

.page-about .limits__item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: rgba(16, 35, 29, .84);
}

.page-about .limits__mark {
  font-family: var(--f-mono);
  font-size: 15px;
  line-height: 1.6;
  color: var(--c-alert);
}

/* ---------- 结尾行动 ---------- */
.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

.page-about .about-ch--final .coord {
  color: var(--c-cyan);
}

.page-about .about-ch--final .prose {
  color: rgba(242, 247, 245, .9);
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .codebox__parts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .steps__item {
    padding-left: 74px;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.3fr) minmax(0, 1fr);
    align-items: end;
  }

  .page-about .about-main {
    grid-template-columns: var(--rail) minmax(0, 1fr);
    gap: clamp(26px, 3vw, 46px);
  }

  .page-about .axis-rail {
    display: flex;
    flex-direction: column;
    gap: 2px;
    position: sticky;
    top: 104px;
    padding: 6px 0;
    border-left: 1px solid var(--c-hairline);
  }

  .page-about .axis-rail__item {
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 3px;
    padding: 10px 12px 10px 16px;
    text-decoration: none;
    color: rgba(242, 247, 245, .55);
    font-size: 13px;
    transition: color var(--t-fast);
  }

  .page-about .axis-rail__item::before {
    content: "";
    position: absolute;
    left: -1px;
    top: 12px;
    bottom: 12px;
    width: 2px;
    border-radius: 2px;
    background-color: transparent;
    transition: background-color var(--t-fast), box-shadow var(--t-fast);
  }

  .page-about .axis-rail__item .mono {
    font-family: var(--f-mono);
    font-size: 11px;
    letter-spacing: .14em;
    font-variant-numeric: tabular-nums;
    color: inherit;
  }

  .page-about .axis-rail__item span:last-child {
    font-family: var(--f-display);
    letter-spacing: .06em;
  }

  .page-about .axis-rail__item:hover,
  .page-about .axis-rail__item:focus-visible {
    color: var(--c-white);
  }

  .page-about .axis-rail__item:hover::before,
  .page-about .axis-rail__item:focus-visible::before {
    background-color: var(--c-amber);
  }

  .page-about .axis-rail__item[aria-current="true"] {
    color: var(--c-cyan);
  }

  .page-about .axis-rail__item[aria-current="true"]::before {
    background-color: var(--c-cyan);
    box-shadow: 0 0 12px rgba(56, 225, 214, .6);
  }

  .page-about .timeline {
    padding-left: 34px;
  }

  .page-about .timeline__item::before {
    left: -34px;
  }
}

@media (min-width: 1080px) {
  .page-about .with-note {
    grid-template-columns: minmax(0, 1fr) var(--note);
    gap: clamp(24px, 3vw, 44px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .breadcrumbs a,
  .page-about .tab,
  .page-about .axis-rail__item,
  .page-about .axis-rail__item::before,
  .page-about .aside-note a,
  .page-about .codebox__code {
    transition: none;
  }
}