/* ===== 使命与档案 / page-about ===== */

.page-about {
  --about-rail: 56px;
  --paper-ink: #16233C;
  --paper-body: #445169;
  --paper-muted: #5F6C85;
  --paper-line: #D5DCE8;
}

/* --- 首屏 --- */
.page-about .about-open {
  padding-block: clamp(36px, 6vw, 76px) clamp(40px, 6vw, 80px);
}

.page-about .about-open .breadcrumb {
  margin-bottom: clamp(20px, 3vw, 32px);
}

.page-about .about-open .display {
  margin: 16px 0 0;
  max-width: 24ch;
}

.page-about .about-open .lede {
  margin: 20px 0 0;
  max-width: 62ch;
}

/* --- 三栏统计条 --- */
.page-about .about-stats {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin: clamp(32px, 5vw, 56px) 0 0;
  padding: 0;
  background: var(--grid);
  border: 1px solid var(--grid);
}

.page-about .about-stats__item {
  background: var(--ink-900);
  padding: 20px 22px 22px;
  min-width: 0;
}

.page-about .about-stats__label {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.page-about .about-stats__value {
  margin: 12px 0 0;
  font-family: var(--font-mono);
  font-size: clamp(30px, 7vw, 44px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.page-about .about-stats__value span {
  margin-left: 8px;
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.page-about .about-stats__item--key .about-stats__value {
  color: var(--draw-red);
}

@media (min-width: 700px) {
  .page-about .about-stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

/* --- 左侧竖向刻度栏 --- */
.page-about .rail {
  display: grid;
  grid-template-columns: 1fr;
}

.page-about .rail__marks {
  display: none;
}

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

@media (min-width: 900px) {
  .page-about .rail {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    column-gap: clamp(28px, 4vw, 48px);
  }

  .page-about .rail__marks {
    display: block;
    position: relative;
    border-left: 1px solid var(--grid);
    background-image: repeating-linear-gradient(
      to bottom,
      var(--grid) 0,
      var(--grid) 1px,
      transparent 1px,
      transparent 28px
    );
    background-repeat: repeat-y;
    background-size: 12px 100%;
    background-position: left top;
    min-height: 100%;
  }

  .page-about .rail__marks::before {
    content: "";
    position: absolute;
    left: -4px;
    top: 0;
    width: 7px;
    height: 7px;
    background: var(--warm-gold);
  }
}

/* --- 使命陈述 --- */
.page-about .about-mission {
  padding-block: clamp(36px, 6vw, 72px);
}

.page-about .about-mission .h2 {
  margin-top: 14px;
  max-width: 20ch;
}

.page-about .about-mission .prose {
  margin-top: 18px;
}

.page-about .about-mission__figure {
  margin: clamp(28px, 4vw, 48px) 0 0;
}

/* --- 版本演进时间轴 --- */
.page-about .about-stages {
  padding-block: clamp(40px, 6vw, 84px);
}

.page-about .about-stages .h2 {
  margin-top: 14px;
  max-width: 22ch;
}

.page-about .about-stages .prose {
  margin-top: 18px;
  max-width: 62ch;
}

.page-about .stage-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  margin: clamp(28px, 4vw, 44px) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .stage-item {
  position: relative;
  border-top: 1px solid var(--grid);
  padding-top: 20px;
  margin-bottom: 24px;
  min-width: 0;
}

.page-about .stage-item::before {
  content: "";
  position: absolute;
  top: -4px;
  left: 0;
  width: 7px;
  height: 7px;
  background: var(--chart-cyan);
}

.page-about .stage-item:last-child {
  margin-bottom: 0;
}

.page-about .stage__head {
  display: flex;
  align-items: baseline;
  gap: 10px;
  list-style: none;
  cursor: pointer;
}

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

.page-about .stage__head::marker {
  content: "";
}

.page-about .stage__head:focus-visible {
  outline: 1px solid var(--warm-gold);
  outline-offset: 3px;
}

.page-about .stage__mark {
  flex: 0 0 auto;
  width: 7px;
  height: 7px;
  background: var(--draw-red);
}

.page-about .stage__name {
  font-family: var(--font-sans);
  font-size: clamp(20px, 2.4vw, 25px);
  font-weight: 800;
  color: var(--text-primary);
}

.page-about .stage__tag {
  margin-left: auto;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--warm-gold);
}

.page-about .stage__body p {
  margin: 12px 0 0;
  font-family: var(--font-serif);
  font-size: 17px;
  line-height: 1.75;
  color: var(--text-muted);
  max-width: 44ch;
}

.page-about .about-stages__figure {
  margin: clamp(28px, 4vw, 44px) 0 0;
}

@media (min-width: 820px) {
  .page-about .stage-list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    border-top: 1px solid var(--grid);
  }

  .page-about .stage-item {
    border-top: 0;
    padding: 26px 26px 0 0;
    margin-bottom: 0;
  }
}

/* --- 案例合集（反白档案纸） --- */
.page-about .about-cases {
  background: var(--paper);
  color: var(--paper-body);
  padding-block: clamp(40px, 6vw, 84px);
}

.page-about .about-cases .eyebrow {
  color: var(--paper-muted);
}

.page-about .about-cases .h2 {
  color: var(--paper-ink);
  margin-top: 14px;
  max-width: 22ch;
}

.page-about .about-cases .prose {
  margin-top: 18px;
  max-width: 62ch;
  color: var(--paper-body);
}

.page-about .about-cases .chips {
  margin-top: clamp(24px, 4vw, 34px);
  flex-wrap: wrap;
  gap: 8px;
}

.page-about .about-cases .chip {
  background: transparent;
  border: 1px solid var(--paper-line);
  color: var(--paper-ink);
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.04em;
  padding: 7px 14px;
  cursor: pointer;
  transition: background 200ms var(--ease), color 200ms var(--ease), border-color 200ms var(--ease);
}

.page-about .about-cases .chip:hover {
  border-color: var(--paper-ink);
}

.page-about .about-cases .chip[aria-pressed="true"] {
  background: var(--ink-900);
  border-color: var(--ink-900);
  color: var(--paper);
}

.page-about .case-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin: clamp(22px, 3vw, 32px) 0 0;
  padding: 0;
  list-style: none;
  background: var(--paper-line);
  border: 1px solid var(--paper-line);
}

.page-about .case {
  background: var(--paper);
  padding: 22px 20px 24px;
  min-width: 0;
}

.page-about .case__no {
  display: block;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--paper-muted);
}

.page-about .case:nth-child(3n + 1) .case__no {
  color: #B03A34;
}

.page-about .case:nth-child(3n + 2) .case__no {
  color: #2E7C8A;
}

.page-about .case__title {
  margin: 10px 0 0;
  font-family: var(--font-sans);
  font-size: 19px;
  font-weight: 800;
  color: var(--paper-ink);
}

.page-about .case__text {
  margin: 10px 0 0;
  font-family: var(--font-serif);
  font-size: 16px;
  line-height: 1.7;
  color: var(--paper-body);
}

.page-about .case-note {
  margin: clamp(22px, 3vw, 30px) 0 0;
  font-family: var(--font-serif);
  font-size: 16px;
  line-height: 1.75;
  color: var(--paper-muted);
}

.page-about .case-note a {
  color: var(--paper-ink);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .case-note a:hover {
  color: #B03A34;
}

@media (min-width: 700px) {
  .page-about .case-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1060px) {
  .page-about .case-list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

/* --- 档案规则 --- */
.page-about .about-rules {
  padding-block: clamp(44px, 7vw, 92px);
}

.page-about .about-rules .h2 {
  margin-top: 14px;
  max-width: 24ch;
}

.page-about .about-rules .prose {
  margin-top: 18px;
  max-width: 58ch;
}

.page-about .field-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin: clamp(26px, 4vw, 38px) 0 0;
  padding: 0;
  list-style: none;
  background: var(--grid);
  border: 1px solid var(--grid);
}

.page-about .field {
  background: var(--ink-800);
  padding: 18px 18px 20px;
  min-width: 0;
}

.page-about .field__no {
  display: block;
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--chart-cyan);
}

.page-about .field__name {
  margin: 10px 0 0;
  font-family: var(--font-sans);
  font-size: 17px;
  font-weight: 700;
  color: var(--text-primary);
}

.page-about .field__desc {
  margin: 8px 0 0;
  font-family: var(--font-serif);
  font-size: 15px;
  line-height: 1.7;
  color: var(--text-muted);
}

@media (min-width: 620px) {
  .page-about .field-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1080px) {
  .page-about .field-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .rule-split {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(24px, 4vw, 40px);
  margin-top: clamp(30px, 5vw, 48px);
}

.page-about .rule-split__figure {
  margin: 0;
}

.page-about .rule-split__text .h3 {
  margin: 0;
}

.page-about .rule-split__text p {
  margin: 14px 0 0;
  font-family: var(--font-serif);
  font-size: 17px;
  line-height: 1.75;
  color: var(--text-muted);
  max-width: 52ch;
}

.page-about .rule-split .plate-fold {
  margin-top: 22px;
  border-top: 1px solid var(--grid);
  border-bottom: 1px solid var(--grid);
  padding: 14px 0;
}

.page-about .rule-split .plate-fold summary {
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--warm-gold);
}

.page-about .rule-split .plate-fold__body p {
  margin: 12px 0 0;
  font-size: 15px;
  color: var(--text-muted);
  max-width: 52ch;
}

.page-about .rule-split .plate-fold__body abbr {
  color: var(--chart-cyan);
  text-decoration: underline dotted;
  text-underline-offset: 3px;
  cursor: help;
}

@media (min-width: 900px) {
  .page-about .rule-split {
    grid-template-columns: minmax(0, 5fr) minmax(0, 6fr);
    align-items: start;
  }
}

/* --- 团队与排班 --- */
.page-about .about-team {
  padding-block: clamp(40px, 6vw, 80px);
}

.page-about .about-team .h2 {
  margin-top: 14px;
  max-width: 22ch;
}

.page-about .about-team .prose {
  margin-top: 18px;
  max-width: 60ch;
}

.page-about .team-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin: clamp(26px, 4vw, 38px) 0 0;
  padding: 0;
  list-style: none;
  background: var(--grid);
  border: 1px solid var(--grid);
}

.page-about .team {
  background: var(--ink-800);
  padding: 24px 22px 26px;
  min-width: 0;
}

.page-about .team__count {
  display: block;
  font-size: clamp(32px, 5vw, 42px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--warm-gold);
}

.page-about .team__role {
  margin: 12px 0 0;
  font-family: var(--font-sans);
  font-size: 18px;
  font-weight: 800;
  color: var(--text-primary);
}

.page-about .team__text {
  margin: 10px 0 0;
  font-family: var(--font-serif);
  font-size: 16px;
  line-height: 1.7;
  color: var(--text-muted);
}

.page-about .team-note {
  margin: clamp(22px, 3vw, 30px) 0 0;
  font-family: var(--font-serif);
  font-size: 16px;
  line-height: 1.75;
  color: var(--text-muted);
  max-width: 62ch;
}

.page-about .team-note a {
  color: var(--chart-cyan);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .team-note a:hover {
  color: var(--warm-gold);
}

@media (min-width: 800px) {
  .page-about .team-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

/* --- 地区与备案 --- */
.page-about .about-region {
  padding-block: clamp(40px, 6vw, 84px);
}

.page-about .about-region .h2 {
  margin-top: 14px;
}

.page-about .about-region .prose {
  margin-top: 18px;
  max-width: 58ch;
}

.page-about .region-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin: clamp(26px, 4vw, 38px) 0 0;
  padding: 0;
  background: var(--grid);
  border: 1px solid var(--grid);
}

.page-about .region-list__row {
  background: var(--ink-900);
  padding: 16px 20px;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px 18px;
  min-width: 0;
}

.page-about .region-list__row dt {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.page-about .region-list__row dd {
  margin: 0;
  flex: 1 1 200px;
  min-width: 0;
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.6;
  color: var(--text-primary);
  overflow-wrap: anywhere;
}

.page-about .region-note {
  margin: clamp(20px, 3vw, 28px) 0 0;
  font-family: var(--font-serif);
  font-size: 16px;
  line-height: 1.75;
  color: var(--text-muted);
  max-width: 62ch;
}

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

/* --- 继续翻阅 --- */
.page-about .about-next {
  padding-block: clamp(32px, 5vw, 60px);
  border-top: 1px solid var(--grid);
}

.page-about .next-links {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
  background: var(--grid);
  border: 1px solid var(--grid);
}

.page-about .next-links a {
  display: block;
  background: var(--ink-900);
  padding: 18px 18px 20px;
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  transition: background 200ms var(--ease), color 200ms var(--ease);
}

.page-about .next-links a:hover,
.page-about .next-links a:focus-visible {
  background: var(--ink-700);
  color: var(--warm-gold);
}

@media (min-width: 700px) {
  .page-about .next-links {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

/* --- 动效退化 --- */
@media (prefers-reduced-motion: reduce) {
  .page-about .about-cases .chip,
  .page-about .next-links a {
    transition: none;
  }
}