.page-about {
  --about-gap: 28px;
  --about-pad: 72px;
}

.page-about .about-crumb {
  padding-top: 24px;
}

.page-about .display-2 {
  margin: 10px 0 0;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding: 28px 0 64px;
}

.page-about .about-hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 32px;
  align-items: end;
}

.page-about .about-hero__title {
  margin: 12px 0 18px;
}

.page-about .about-hero__text {
  margin: 18px 0 0;
  max-width: 48ch;
  font-size: var(--fs-15);
  line-height: 1.9;
  color: var(--paper);
  opacity: .8;
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.page-about .about-hero__media {
  margin: 0;
}

.page-about .about-hero__media .media-window__img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

/* ---------- 统计条 ---------- */
.page-about .about-stats {
  margin-top: 48px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  border-top: 1px solid var(--hairline);
}

.page-about .about-stats .stat {
  display: flex;
  flex-direction: column;
  gap: 5px;
  padding: 18px 12px 18px 0;
  border-bottom: 1px solid var(--hairline-soft);
}

.page-about .about-stats .stat__value {
  font-family: var(--font-mono);
  font-size: var(--fs-26);
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--mint);
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
}

.page-about .about-stats .stat__label {
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: .06em;
  color: var(--line);
  line-height: 1.6;
}

/* ---------- 章节通用 ---------- */
.page-about .about-chapter {
  padding: var(--about-pad) 0;
  border-top: 1px solid var(--hairline-soft);
}

.page-about .about-chapter__lead {
  margin: 18px 0 0;
  max-width: 60ch;
  font-size: var(--fs-15);
  line-height: 1.9;
  opacity: .82;
}

/* ---------- 起点 ---------- */
.page-about .origin__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 36px;
  align-items: start;
}

.page-about .origin__copy p {
  margin: 18px 0 0;
  max-width: 58ch;
  font-size: var(--fs-15);
  line-height: 1.9;
  opacity: .82;
}

.page-about .origin__lead {
  font-family: var(--font-serif);
  font-size: var(--fs-20);
  line-height: 1.75;
  color: var(--mint-soft);
  opacity: 1 !important;
}

.page-about .axis-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .axis {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 6px 12px;
  padding: 18px 0;
  border-top: 1px solid var(--hairline);
}

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

.page-about .axis__key {
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  color: var(--mint);
  letter-spacing: .08em;
  padding-top: 3px;
}

.page-about .axis__name {
  font-size: var(--fs-17);
  font-weight: 700;
  letter-spacing: .01em;
}

.page-about .axis__desc {
  grid-column: 2;
  font-size: var(--fs-13);
  line-height: 1.85;
  color: var(--line);
}

/* ---------- 四条准则 ---------- */
.page-about .principles {
  margin-top: 32px;
}

.page-about .principle {
  border-top: 1px solid var(--hairline);
}

.page-about .principle:last-of-type {
  border-bottom: 1px solid var(--hairline);
}

.page-about .principle__head {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr) 20px;
  align-items: baseline;
  gap: 14px;
  padding: 22px 2px 22px 0;
  cursor: pointer;
  list-style: none;
}

.page-about .principle__head::-webkit-details-marker {
  display: none;
}

.page-about .principle__head:focus-visible {
  outline: 2px solid var(--mint);
  outline-offset: 4px;
}

.page-about .principle__num {
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  color: var(--mint);
  letter-spacing: .08em;
}

.page-about .principle__title {
  font-size: var(--fs-20);
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.45;
}

.page-about .principle__cue {
  font-family: var(--font-mono);
  font-size: var(--fs-17);
  color: var(--line);
  text-align: right;
  transition: transform var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .principle[open] .principle__cue {
  transform: rotate(45deg);
  color: var(--mint);
}

.page-about .principle__body {
  margin: 0 0 26px;
  padding-left: 48px;
  max-width: 64ch;
  font-size: var(--fs-15);
  line-height: 1.9;
  opacity: .82;
}

.page-about .principles__figure {
  margin: 40px 0;
  max-width: 100%;
}

.page-about .principles__figure .media-window__img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

/* ---------- 三道校验 ---------- */
.page-about .process__figure {
  margin: 32px 0 40px;
}

.page-about .process__figure .media-window__img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .process__track {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 28px;
}

.page-about .process__step {
  position: relative;
  border-top: 1px solid var(--hairline);
  padding-top: 20px;
}

.page-about .process__step::before {
  content: "";
  position: absolute;
  top: -3px;
  left: 0;
  width: 6px;
  height: 6px;
  background: var(--mint);
}

.page-about .process__num {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: .14em;
  color: var(--mint);
}

.page-about .process__name {
  margin: 10px 0 10px;
  font-size: var(--fs-17);
  font-weight: 700;
}

.page-about .process__text {
  margin: 0;
  font-size: var(--fs-15);
  line-height: 1.85;
  opacity: .82;
}

/* ---------- 团队分工 ---------- */
.page-about .team {
  list-style: none;
  margin: 36px 0 0;
  padding: 0;
}

.page-about .team__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 56px;
  align-items: center;
  gap: 8px 16px;
  padding: 18px 0;
  border-top: 1px solid var(--hairline);
}

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

.page-about .team__name {
  margin: 0;
  font-size: var(--fs-15);
  font-weight: 700;
  letter-spacing: .01em;
}

.page-about .team__count {
  font-family: var(--font-mono);
  font-size: var(--fs-17);
  color: var(--mint);
  text-align: right;
  font-variant-numeric: tabular-nums;
}

.page-about .team__bar {
  grid-column: 1 / -1;
  order: 3;
  height: 8px;
  background: var(--rail);
  overflow: hidden;
}

.page-about .team__fill {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--mint), var(--mint-soft));
}

.page-about .team__fill--edit { width: 43.75%; }
.page-about .team__fill--data { width: 18.75%; }
.page-about .team__fill--care { width: 23.4%; }
.page-about .team__fill--design { width: 14.1%; }

.page-about .team__duty {
  grid-column: 1 / -1;
  margin: 0;
  max-height: 0;
  opacity: 0;
  overflow: hidden;
  font-size: var(--fs-13);
  line-height: 1.8;
  color: var(--line);
  transition: max-height var(--dur) var(--ease), opacity var(--dur) var(--ease);
}

.page-about .team__row:hover .team__duty,
.page-about .team__row:focus-within .team__duty {
  max-height: 6em;
  opacity: 1;
}

/* ---------- 版本演进 ---------- */
.page-about .about-chapter--versions {
  background: var(--wine);
  border-top: 0;
  color: var(--paper);
}

.page-about .versions__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 36px;
  align-items: start;
}

.page-about .versions__jumps {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-top: 28px;
  padding-left: 22px;
}

.page-about .versions__jumps::before {
  content: "";
  position: absolute;
  left: 0;
  top: 6px;
  bottom: 6px;
  width: 1px;
  background: rgba(233, 242, 237, .35);
}

.page-about .versions__jump {
  position: relative;
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  letter-spacing: .1em;
  color: var(--paper);
  text-decoration: none;
  opacity: .72;
  transition: opacity var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .versions__jump::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 50%;
  width: 7px;
  height: 7px;
  margin-top: -4px;
  background: var(--wine);
  border: 1px solid rgba(233, 242, 237, .6);
  border-radius: 50%;
}

.page-about .versions__jump:hover,
.page-about .versions__jump[aria-current="true"] {
  opacity: 1;
  color: var(--amber);
}

.page-about .versions__jump[aria-current="true"]::before {
  background: var(--mint);
  border-color: var(--mint);
}

.page-about .versions__jump:focus-visible {
  outline: 2px solid var(--mint);
  outline-offset: 4px;
}

.page-about .version {
  border-top: 1px solid rgba(233, 242, 237, .28);
  padding: 26px 0;
}

.page-about .version:first-child {
  border-top: 0;
  padding-top: 0;
}

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

.page-about .version__num {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--fs-36);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1;
  color: var(--amber);
}

.page-about .version__title {
  margin: 14px 0 10px;
  font-size: var(--fs-20);
  font-weight: 700;
}

.page-about .version p {
  margin: 0;
  max-width: 62ch;
  font-size: var(--fs-15);
  line-height: 1.9;
}

/* ---------- 内容来源 ---------- */
.page-about .source__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 28px;
  align-items: start;
}

.page-about .source__body p {
  margin: 0 0 18px;
  max-width: 62ch;
  font-size: var(--fs-15);
  line-height: 1.9;
  opacity: .82;
}

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

.page-about .source__body a {
  color: var(--mint);
  text-decoration: none;
  border-bottom: 1px solid var(--hairline);
}

.page-about .source__body a:hover {
  color: var(--mint-soft);
}

/* ---------- 收束 ---------- */
.page-about .reasons {
  list-style: none;
  margin: 36px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0;
}

.page-about .reason {
  border-top: 1px solid var(--hairline);
  padding: 20px 0;
}

.page-about .reason__num {
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: .12em;
  color: var(--mint);
}

.page-about .reason__title {
  margin: 10px 0 10px;
  font-size: var(--fs-17);
  font-weight: 700;
}

.page-about .reason p {
  margin: 0;
  font-size: var(--fs-15);
  line-height: 1.85;
  opacity: .82;
}

.page-about .about-chapter--closing {
  padding-bottom: 96px;
}

.page-about .about-cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
  margin-top: 48px;
}

.page-about .about-cta p {
  margin: 0 20px 0 0;
  font-size: var(--fs-15);
  line-height: 1.8;
  opacity: .8;
}

/* ---------- 返回顶部 ---------- */
.page-about .to-top {
  position: fixed;
  right: 20px;
  bottom: 88px;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  background: var(--panel);
  border: 1px solid var(--hairline);
  color: var(--mint);
  font-family: var(--font-mono);
  font-size: var(--fs-15);
  cursor: pointer;
  z-index: 20;
}

.page-about .to-top:hover {
  border-color: var(--mint);
}

.page-about .to-top:focus-visible {
  outline: 2px solid var(--mint);
  outline-offset: 3px;
}

/* ---------- 断点 ---------- */
@media (min-width: 720px) {
  .page-about {
    --about-pad: 96px;
  }

  .page-about .about-stats .stat {
    padding-right: 18px;
  }

  .page-about .team__row {
    grid-template-columns: 150px minmax(0, 1fr) 56px;
    gap: 10px 24px;
  }

  .page-about .team__bar {
    grid-column: 2;
    order: 0;
  }

  .page-about .team__count {
    grid-column: 3;
  }

  .page-about .team__duty {
    grid-column: 2 / -1;
  }

  .page-about .to-top {
    right: 32px;
    bottom: 32px;
  }
}

@media (min-width: 900px) {
  .page-about {
    --about-pad: 120px;
  }

  .page-about .about-hero {
    padding: 40px 0 88px;
  }

  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    gap: 56px;
  }

  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    margin-top: 56px;
  }

  .page-about .about-stats .stat {
    padding: 22px 24px 22px 24px;
    border-bottom: 0;
    border-left: 1px solid var(--hairline-soft);
  }

  .page-about .about-stats .stat:first-child {
    padding-left: 0;
    border-left: 0;
  }

  .page-about .origin__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 4fr);
    gap: 72px;
  }

  .page-about .principles__figure {
    margin: 48px 0 48px auto;
    max-width: 400px;
  }

  .page-about .process__track {
    grid-template-columns: 5fr 4fr 3fr;
    gap: 32px;
  }

  .page-about .versions__grid {
    grid-template-columns: 240px minmax(0, 1fr);
    gap: 72px;
  }

  .page-about .versions__rail {
    position: sticky;
    top: 88px;
  }

  .page-about .source__grid {
    grid-template-columns: minmax(0, 4fr) minmax(0, 7fr);
    gap: 72px;
  }

  .page-about .reasons {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 32px;
  }

  .page-about .about-chapter--closing {
    padding-bottom: 140px;
  }
}

@media (hover: none) {
  .page-about .team__duty {
    max-height: none;
    opacity: 1;
    margin-top: 2px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .principle__cue,
  .page-about .team__duty,
  .page-about .versions__jump {
    transition: none;
  }
}