.page-about {
  --about-rail: 224px;
  --about-col-gap: clamp(24px, 4vw, 56px);
  display: block;
  background: var(--ink);
  color: var(--cream);
  padding-bottom: clamp(56px, 9vw, 120px);
}

.page-about .about-crumb {
  padding-top: calc(var(--header-h) + 22px);
  padding-bottom: 4px;
}

.page-about .about-masthead {
  padding: clamp(26px, 4vw, 52px) 0 clamp(34px, 5vw, 66px);
}

.page-about .about-masthead__kicker {
  color: var(--gold);
  margin: 0 0 18px;
}

.page-about .about-masthead__title {
  margin: 0 0 20px;
  max-width: 20ch;
  font-family: var(--font-cn);
  font-size: clamp(2.1rem, 5.6vw, 4.4rem);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--cream);
}

.page-about .about-masthead__lede {
  max-width: 64ch;
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

@media (min-width: 760px) {
  .page-about .about-masthead__lede {
    font-size: 16px;
  }
}

.page-about .about-masthead__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: clamp(30px, 4.5vw, 54px) 0 0;
  background: var(--line);
  border-top: 1px solid var(--copper);
  border-bottom: 1px solid var(--line);
}

@media (min-width: 720px) {
  .page-about .about-masthead__stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .about-masthead__stats > div {
  background: var(--ink);
  padding: 16px clamp(10px, 2vw, 22px);
}

.page-about .about-masthead__stats dt {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--mist);
}

.page-about .about-masthead__stats dd {
  margin: 10px 0 0;
  font-family: var(--font-mono);
  font-size: clamp(1.4rem, 3.4vw, 2.3rem);
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--gold);
}

/* 主体两栏：左侧年份索引 + 右侧堆叠画板 */
.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(32px, 5vw, 56px);
}

@media (min-width: 1000px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: var(--about-col-gap);
  }
}

.page-about .about-rail {
  align-self: start;
  border-top: 1px solid var(--copper);
  padding-top: 14px;
}

@media (min-width: 1000px) {
  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h) + 26px);
  }
}

.page-about .about-rail__title {
  margin: 0 0 12px;
  color: var(--mist);
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 6px;
  display: flex;
  gap: 10px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

@media (min-width: 1000px) {
  .page-about .about-rail__list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    padding-bottom: 0;
  }
}

.page-about .about-rail__year {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 9px 0 10px;
  border-bottom: 1px solid var(--line);
  color: var(--mist);
  font-size: 13px;
  text-decoration: none;
  white-space: nowrap;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

@media (min-width: 1000px) {
  .page-about .about-rail__year {
    border-bottom: 0;
    border-left: 1px solid var(--line);
    padding: 10px 0 10px 14px;
    font-size: 12px;
  }
}

.page-about .about-rail__year .num {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.02em;
  color: var(--gold);
}

.page-about .about-rail__year:hover,
.page-about .about-rail__year:focus-visible {
  color: var(--gold-hot);
  border-color: var(--gold);
}

/* 堆叠画板 */
.page-about .about-sec {
  border-top: 1px solid var(--copper);
  padding-top: clamp(22px, 3vw, 38px);
  padding-bottom: clamp(40px, 6vw, 78px);
  scroll-margin-top: calc(var(--header-h) + 24px);
}

.page-about .about-sec:last-of-type {
  padding-bottom: 0;
  border-bottom: 1px solid var(--line);
}

.page-about .about-sec__lede {
  max-width: 62ch;
  margin: 0 0 clamp(20px, 3vw, 32px);
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

/* 沿革时间线 */
.page-about .about-timeline {
  display: grid;
}

.page-about .about-era {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 8px;
  padding: 20px 0 20px 20px;
  border-left: 1px solid var(--line);
  scroll-margin-top: calc(var(--header-h) + 24px);
}

.page-about .about-era::before {
  content: "";
  position: absolute;
  left: -1px;
  top: 26px;
  width: 10px;
  height: 1px;
  background: var(--gold);
}

.page-about .about-era + .about-era {
  border-top: 1px solid var(--line);
}

@media (min-width: 720px) {
  .page-about .about-era {
    grid-template-columns: 108px minmax(0, 1fr);
    align-items: start;
    gap: clamp(16px, 2.4vw, 34px);
    padding-left: 26px;
  }
}

.page-about .about-era__year {
  font-family: var(--font-mono);
  font-size: clamp(1.4rem, 3vw, 2rem);
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--gold);
}

.page-about .about-era h3 {
  margin: 0 0 8px;
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--cream);
}

.page-about .about-era p {
  max-width: 66ch;
  margin: 0 0 8px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

.page-about .about-era__meta {
  margin: 12px 0 0;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--jade);
}

/* 职责矩阵 */
.page-about .about-matrix {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

@media (min-width: 760px) {
  .page-about .about-matrix {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.page-about .about-cell {
  background: var(--ink);
  padding: clamp(18px, 2.6vw, 28px);
  transition: background 0.3s var(--ease);
}

.page-about .about-cell:hover,
.page-about .about-cell:focus-within {
  background: var(--panel);
}

.page-about .about-cell:focus-visible {
  outline: 1px solid var(--gold);
  outline-offset: -1px;
}

.page-about .about-cell__idx {
  color: var(--gold);
}

.page-about .about-cell h3 {
  margin: 10px 0 6px;
  font-size: 1.2rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--cream);
}

.page-about .about-cell__size {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--jade);
}

.page-about .about-cell__duties {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 7px;
}

.page-about .about-cell__duties li {
  position: relative;
  padding-left: 16px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--mist);
}

.page-about .about-cell__duties li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.82em;
  width: 8px;
  height: 1px;
  background: var(--copper);
}

.page-about .about-cell__more {
  margin: 14px 0 0;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  font-size: 13px;
  line-height: 1.7;
  color: var(--cream);
  max-height: 260px;
  opacity: 1;
  overflow: hidden;
  transition: max-height 0.32s var(--ease), opacity 0.32s var(--ease);
}

@media (hover: hover) and (min-width: 900px) {
  .page-about .about-cell__more {
    max-height: 0;
    opacity: 0;
    padding-top: 0;
    border-top-color: transparent;
    transition: max-height 0.32s var(--ease), opacity 0.32s var(--ease), padding-top 0.32s var(--ease);
  }

  .page-about .about-cell:hover .about-cell__more,
  .page-about .about-cell:focus-within .about-cell__more {
    max-height: 260px;
    opacity: 1;
    padding-top: 12px;
    border-top-color: var(--line);
  }
}

.page-about .about-media {
  margin: clamp(26px, 4vw, 46px) 0 0;
}

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

/* 编审流程 */
.page-about .about-flow {
  margin: clamp(22px, 3.5vw, 40px) 0 0;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  padding-bottom: 6px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-flow__svg {
  display: block;
  width: 100%;
  min-width: 640px;
  height: auto;
  padding: 16px 0;
}

.page-about .about-flow__axis {
  stroke: var(--copper);
  stroke-width: 1;
}

.page-about .about-flow__node circle {
  fill: var(--ink);
  stroke: var(--gold);
  stroke-width: 1.5;
}

.page-about .about-flow__node text {
  fill: var(--cream);
  font-family: var(--font-cn);
  font-size: 16px;
  font-weight: 700;
  letter-spacing: -0.01em;
  text-anchor: middle;
}

.page-about .about-flow__node .about-flow__sub {
  fill: var(--mist);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 400;
  letter-spacing: 0.05em;
}

.page-about .about-folds {
  margin-top: clamp(22px, 3.5vw, 38px);
  border-top: 1px solid var(--line);
}

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

.page-about .about-fold summary {
  position: relative;
  padding: 15px 30px 15px 0;
  list-style: none;
  cursor: pointer;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: -0.005em;
  color: var(--cream);
  transition: color 0.2s var(--ease);
}

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

.page-about .about-fold summary::after {
  content: "+";
  position: absolute;
  right: 4px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--gold);
}

.page-about .about-fold[open] summary::after {
  content: "−";
}

.page-about .about-fold summary:hover,
.page-about .about-fold summary:focus-visible {
  color: var(--gold-hot);
}

.page-about .about-fold__body {
  max-width: 70ch;
  padding: 0 0 20px;
}

.page-about .about-fold__body p {
  margin: 0 0 10px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

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

/* 版本追溯 */
.page-about .about-trace {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 36px);
  align-items: start;
}

@media (min-width: 860px) {
  .page-about .about-trace {
    grid-template-columns: minmax(0, 7fr) minmax(0, 4fr);
  }
}

.page-about .about-trace__text p {
  max-width: 64ch;
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

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

.page-about .about-trace .about-media {
  margin: 0;
}

.page-about .about-trace__chain {
  list-style: none;
  margin: clamp(22px, 3.2vw, 36px) 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-trace__chain li {
  background: var(--ink);
}

.page-about .about-trace__chain a {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px 16px;
  padding: 12px 4px;
  font-size: 14px;
  color: var(--cream);
  text-decoration: none;
  transition: color 0.2s var(--ease), padding-left 0.2s var(--ease);
}

.page-about .about-trace__chain a:hover,
.page-about .about-trace__chain a:focus-visible {
  color: var(--gold-hot);
  padding-left: 12px;
}

.page-about .about-trace__chain .mono {
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--mist);
}

/* 更新节奏 */
.page-about .about-cadence {
  display: grid;
  gap: 1px;
  background: var(--line);
  border-top: 1px solid var(--copper);
  border-bottom: 1px solid var(--line);
}

.page-about .about-cadence__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 10px;
  background: var(--ink);
  padding: clamp(18px, 2.6vw, 28px) clamp(12px, 2vw, 22px);
}

@media (min-width: 720px) {
  .page-about .about-cadence__row {
    grid-template-columns: minmax(0, 200px) minmax(0, 1fr);
    align-items: center;
    gap: clamp(16px, 3vw, 44px);
  }
}

.page-about .about-cadence__num {
  font-family: var(--font-mono);
  font-size: clamp(2.3rem, 6vw, 4.2rem);
  line-height: 0.88;
  letter-spacing: -0.045em;
  color: var(--gold);
}

.page-about .about-cadence__row h3 {
  margin: 0 0 8px;
  font-size: 1.05rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--cream);
}

.page-about .about-cadence__row p {
  max-width: 62ch;
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--mist);
}

/* 联系与纠错 */
.page-about .about-contact {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(18px, 3vw, 34px);
}

@media (min-width: 820px) {
  .page-about .about-contact {
    grid-template-columns: minmax(0, 6fr) minmax(0, 5fr);
    align-items: start;
  }
}

.page-about .about-contact__main p {
  max-width: 58ch;
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

.page-about .about-contact__mail {
  margin: 18px 0 0;
  padding-left: 14px;
  border-left: 2px solid var(--gold);
  font-family: var(--font-mono);
  font-size: clamp(14px, 1.9vw, 17px);
  letter-spacing: 0.01em;
  color: var(--gold-hot);
  overflow-wrap: anywhere;
}

.page-about .about-contact__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 8px;
  align-content: start;
}

.page-about .about-contact__list li {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  border: 1px solid var(--line);
  font-size: 14px;
  line-height: 1.6;
  color: var(--mist);
}

.page-about .about-contact__list li::before {
  content: "";
  flex: none;
  width: 6px;
  height: 6px;
  background: var(--jade);
  transform: rotate(45deg);
}

.page-about .about-contact__boundary {
  margin: clamp(20px, 3vw, 32px) 0 0;
  padding: 16px 18px;
  border-left: 2px solid var(--clay);
  background: var(--ink-deep);
  font-size: 13px;
  line-height: 1.75;
  color: var(--mist);
}

.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(20px, 3vw, 30px);
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition: none !important;
    animation: none !important;
  }
}