.page-about {
  --about-rule: rgba(242, 240, 233, .14);
  --about-soft: rgba(242, 240, 233, .06);
  display: block;
}

.page-about a:focus-visible,
.page-about button:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 3px;
}

/* ---------- 顶部条 ---------- */
.page-about .about-topline {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem 1.5rem;
  align-items: baseline;
  justify-content: space-between;
  padding-top: 1.25rem;
  padding-bottom: 1rem;
  border-bottom: 2px solid var(--ink-600);
}

.page-about .about-topline__meta {
  margin: 0;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .08em;
  color: var(--stone);
}

/* ---------- 首屏 ---------- */
.page-about .about-masthead {
  padding-top: 2.75rem;
  padding-bottom: 2.5rem;
}

.page-about .about-masthead__kicker {
  margin: 0 0 1rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .2em;
  color: var(--cyan);
}

.page-about .about-masthead__head {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
}

.page-about .about-masthead__title {
  margin: 0 0 2rem;
  max-width: 15em;
  font-size: clamp(1.9rem, 6.4vw, 3.4rem);
  font-weight: 900;
  line-height: 1.12;
  letter-spacing: -.015em;
}

.page-about .about-masthead__side {
  flex: none;
  padding-top: .4rem;
  writing-mode: vertical-rl;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .3em;
  color: var(--stone);
  user-select: none;
}

.page-about .about-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 2rem;
}

.page-about .about-lead p {
  margin: 0 0 1.1rem;
  max-width: var(--measure);
  line-height: 1.9;
  color: var(--paper);
}

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

/* ---------- 章节索引卡 ---------- */
.page-about .about-index {
  border: 2px solid var(--ink-600);
  background: var(--ink-800);
  box-shadow: var(--shadow-hard);
  padding: 1.15rem 1.15rem 1rem;
}

.page-about .about-index__legend {
  margin: 0 0 .9rem;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .18em;
  color: var(--stone);
}

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

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

.page-about .about-index__link {
  display: flex;
  align-items: baseline;
  gap: .8rem;
  padding: .55rem 0;
  color: var(--paper);
  text-decoration: none;
  font-size: .95rem;
  transition: color var(--t-fast);
}

.page-about .about-index__link:hover {
  color: var(--cyan);
}

.page-about .about-index__num {
  flex: none;
  min-width: 1.9em;
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .08em;
  color: var(--cyan);
}

/* ---------- 呼吸区 ---------- */
.page-about .about-breather {
  height: 3.25rem;
  background-image:
    linear-gradient(var(--about-soft) 1px, transparent 1px),
    linear-gradient(90deg, var(--about-soft) 1px, transparent 1px);
  background-size: 34px 34px;
}

/* ---------- 章节通用 ---------- */
.page-about .about-block {
  padding-top: 2.5rem;
  padding-bottom: 3rem;
}

.page-about .about-chapter {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: baseline;
  column-gap: 1rem;
  row-gap: .4rem;
  padding-bottom: 1rem;
  margin-bottom: 2rem;
  border-bottom: 2px solid var(--ink-600);
}

.page-about .about-chapter__num {
  margin: 0;
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 5vw, 2.5rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--cyan);
}

.page-about .about-chapter__title {
  margin: 0;
  font-size: clamp(1.15rem, 3.4vw, 1.65rem);
  line-height: 1.3;
}

.page-about .about-chapter__note {
  grid-column: 1 / -1;
  margin: 0;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .08em;
  color: var(--stone);
}

.page-about .about-prose p {
  margin: 0 0 1rem;
  max-width: var(--measure);
  line-height: 1.9;
}

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

.page-about .about-prose--after {
  margin-top: 2.25rem;
}

.page-about .about-callout {
  margin: 1.75rem 0 0;
  max-width: var(--measure);
  padding: .2rem 0 .2rem 1rem;
  border-left: 3px solid var(--amber);
  font-family: var(--font-mono);
  font-size: .78rem;
  line-height: 1.85;
  color: var(--stone);
}

/* ---------- 图片 ---------- */
.page-about .about-figure {
  margin: 0 0 2rem;
  border: 2px solid var(--ink-600);
  background: var(--ink-800);
  box-shadow: var(--shadow-hard);
}

.page-about .about-figure--tight {
  margin-bottom: 0;
}

.page-about .about-figure--square {
  max-width: 30rem;
  margin-top: 2.5rem;
  margin-bottom: 0;
}

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

.page-about .about-figure__cap {
  margin: 0;
  padding: .7rem .9rem;
  border-top: 2px solid var(--ink-600);
  font-family: var(--font-mono);
  font-size: .7rem;
  line-height: 1.7;
  letter-spacing: .04em;
  color: var(--stone);
}

/* ---------- 时间轴 ---------- */
.page-about .timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 1.75rem;
  list-style: none;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 6px;
  top: .55rem;
  bottom: .55rem;
  width: 2px;
  background: var(--ink-600);
}

.page-about .timeline__stage {
  position: relative;
  padding-bottom: 2.1rem;
}

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

.page-about .timeline__stage::before {
  content: "";
  position: absolute;
  left: calc(-1.75rem + 1px);
  top: .5rem;
  width: 12px;
  height: 12px;
  background: var(--ink-900);
  border: 2px solid var(--cyan);
  transition: background var(--t-fast);
}

.page-about .timeline__stage:hover::before,
.page-about .timeline__stage:focus-within::before {
  background: var(--cyan);
}

.page-about .timeline__code {
  margin: 0 0 .3rem;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .18em;
  color: var(--amber);
}

.page-about .timeline__period {
  margin: 0 0 .45rem;
  font-family: var(--font-mono);
  font-size: .95rem;
  font-weight: 700;
  color: var(--cyan);
}

.page-about .timeline__title {
  margin: 0 0 .5rem;
  font-size: 1.05rem;
  line-height: 1.5;
}

.page-about .timeline__text {
  margin: 0 0 .6rem;
  max-width: var(--measure);
  line-height: 1.85;
}

.page-about .timeline__meta {
  margin: 0;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .06em;
  color: var(--stone);
}

/* ---------- 维护小组 ---------- */
.page-about .team-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 2rem;
}

.page-about .team-map {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.15rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .team-node {
  height: 100%;
  padding: 1.1rem 1.1rem 1.2rem;
  border: 2px solid var(--ink-600);
  background: var(--ink-800);
  box-shadow: var(--shadow-hard);
  transition: border-color var(--t-base);
}

.page-about .team-node:hover,
.page-about .team-node:focus-within {
  border-color: var(--cyan);
}

.page-about .team-node__code {
  margin: 0 0 .45rem;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .18em;
  color: var(--amber);
}

.page-about .team-node__name {
  margin: 0 0 .6rem;
  font-size: 1.05rem;
  line-height: 1.4;
}

.page-about .team-node__duty {
  margin: 0 0 .85rem;
  font-size: .92rem;
  line-height: 1.85;
}

.page-about .team-node__hand {
  margin: 0;
  padding-top: .7rem;
  border-top: 1px solid var(--about-rule);
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .05em;
  color: var(--cyan);
}

/* ---------- 版本阶梯 ---------- */
.page-about .ladder {
  margin: 2rem 0 0;
  padding: 0;
  list-style: none;
}

.page-about .ladder__step {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: .4rem;
  padding: 1rem 0 1.2rem;
  border-top: 2px solid var(--ink-600);
}

.page-about .ladder__step:last-child {
  border-bottom: 2px solid var(--ink-600);
}

.page-about .ladder__step--current {
  background-image: linear-gradient(90deg, rgba(53, 224, 208, .1), transparent 70%);
}

.page-about .ladder__code {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--cyan);
}

.page-about .ladder__step--current .ladder__code {
  color: var(--amber);
}

.page-about .ladder__title {
  margin: 0;
  font-size: 1rem;
  line-height: 1.5;
}

.page-about .ladder__text {
  margin: 0;
  max-width: var(--measure);
  line-height: 1.85;
  color: var(--stone);
}

/* ---------- 地区口径 ---------- */
.page-about .region-rules {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.25rem;
  align-items: start;
}

.page-about .region-rule {
  padding: 1.1rem 1.1rem 1.2rem;
  border: 2px solid var(--ink-600);
  border-top-width: 6px;
  background: var(--ink-800);
}

.page-about .region-rule--gz {
  border-top-color: var(--cyan);
}

.page-about .region-rule--cd {
  border-top-color: var(--clay);
}

.page-about .region-rule--nj {
  border-top-color: var(--moss);
}

.page-about .region-rule__tag {
  display: inline-block;
  margin: 0 0 .75rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .16em;
}

.page-about .region-rule__title {
  margin: 0 0 .6rem;
  font-size: 1.05rem;
  line-height: 1.45;
}

.page-about .region-rule__text {
  margin: 0 0 .8rem;
  font-size: .92rem;
  line-height: 1.85;
}

.page-about .region-rule__meta {
  margin: 0;
  padding-top: .65rem;
  border-top: 1px solid var(--about-rule);
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .05em;
  color: var(--stone);
}

/* ---------- 归档 ---------- */
.page-about .archive-list {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0;
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 2px solid var(--ink-600);
}

.page-about .archive-item {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: .4rem;
  padding: 1.1rem 0;
  border-bottom: 1px solid var(--about-rule);
}

.page-about .archive-item__code {
  margin: 0;
  font-family: var(--font-mono);
  font-size: .75rem;
  letter-spacing: .18em;
  color: var(--amber);
}

.page-about .archive-item__text {
  margin: 0;
  max-width: var(--measure);
  line-height: 1.85;
}

/* ---------- 关联入口 ---------- */
.page-about .about-links {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1rem;
  margin-top: 2.5rem;
}

.page-about .about-links__item {
  display: flex;
  flex-direction: column;
  gap: .5rem;
  padding: 1rem 1.1rem;
  border: 2px dashed var(--ink-600);
  color: var(--paper);
  text-decoration: none;
  transition: border-color var(--t-base), color var(--t-base);
}

.page-about .about-links__item:hover {
  border-color: var(--cyan);
  border-style: solid;
  color: var(--cyan);
}

.page-about .about-links__label {
  font-size: 1rem;
  font-weight: 700;
}

.page-about .about-links__desc {
  font-size: .84rem;
  line-height: 1.7;
  color: var(--stone);
}

/* ---------- 收尾 ---------- */
.page-about .about-outro {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  margin-top: 2.5rem;
  padding: 1.35rem 1.25rem;
  border: 2px solid var(--paper);
  background: var(--ink-800);
  box-shadow: var(--shadow-hard-cyan);
}

.page-about .about-outro__text {
  margin: 0;
  max-width: var(--measure);
  line-height: 1.85;
}

.page-about .about-outro__actions {
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
}

/* ---------- 断点 ---------- */
@media (max-width: 639px) {
  .page-about .about-masthead__side {
    display: none;
  }
}

@media (min-width: 720px) {
  .page-about .about-split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: 3rem;
    align-items: start;
  }

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

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

  .page-about .ladder__step {
    grid-template-columns: 7rem minmax(0, 1fr);
    align-items: baseline;
    column-gap: 1.5rem;
    padding: 1.15rem 0 1.4rem;
  }

  .page-about .ladder__code {
    grid-column: 1;
    grid-row: 1 / span 2;
  }

  .page-about .ladder__title,
  .page-about .ladder__text {
    grid-column: 2;
  }

  .page-about .ladder__step:nth-child(2) { margin-inline-start: 6%; }
  .page-about .ladder__step:nth-child(3) { margin-inline-start: 12%; }
  .page-about .ladder__step:nth-child(4) { margin-inline-start: 18%; }
  .page-about .ladder__step:nth-child(5) { margin-inline-start: 24%; }

  .page-about .archive-item {
    grid-template-columns: 5.5rem minmax(0, 1fr);
    align-items: baseline;
    column-gap: 1.5rem;
    padding: 1.2rem 0;
  }

  .page-about .about-outro {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    gap: 2rem;
    padding: 1.6rem 1.5rem;
  }
}

@media (min-width: 900px) {
  .page-about .team-layout {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    gap: 2.75rem;
    align-items: start;
  }

  .page-about .about-block {
    padding-top: 3.25rem;
    padding-bottom: 3.75rem;
  }

  .page-about .about-breather {
    height: 4.5rem;
  }
}

@media (min-width: 1000px) {
  .page-about .region-rules {
    grid-template-columns: repeat(12, minmax(0, 1fr));
    gap: 1.5rem;
  }

  .page-about .region-rule:nth-child(1) {
    grid-column: 1 / span 5;
  }

  .page-about .region-rule:nth-child(2) {
    grid-column: 6 / span 4;
    margin-top: 2.5rem;
  }

  .page-about .region-rule:nth-child(3) {
    grid-column: 10 / span 3;
    margin-top: 5rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about * {
    transition-duration: 1ms !important;
  }
}