.page-about {
  --rail-w: 196px;
  --about-gap: 32px;
  padding-bottom: 88px;
  background:
    radial-gradient(1100px 620px at 88% -8%, rgba(31, 107, 69, 0.3), transparent 62%),
    linear-gradient(180deg, var(--bg) 0%, var(--bg) 62%, var(--bg-2) 100%);
  color: var(--mist);
}

.page-about .breadcrumbs {
  padding: 18px 0 0;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--gray);
}

.page-about .breadcrumbs a {
  color: var(--mint);
  text-decoration: none;
}

.page-about .breadcrumbs a:hover {
  color: var(--lime);
}

.page-about .breadcrumbs span[aria-hidden] {
  margin: 0 8px;
  color: var(--line);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero__grid {
  display: grid;
  gap: 28px;
  padding: 26px 0 44px;
}

.page-about .about-title {
  margin: 12px 0 16px;
  font-size: clamp(40px, 10vw, 78px);
  font-weight: 200;
  line-height: 1.02;
  letter-spacing: -0.03em;
  color: var(--mist);
}

.page-about .lede {
  max-width: 52ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--gray);
}

.page-about .hero-points {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 22px;
  margin: 22px 0 0;
  padding: 0;
  list-style: none;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--gray);
}

.page-about .hero-points .num {
  color: var(--lime);
  margin-right: 6px;
}

.page-about .hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

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

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

.page-about .v-figure,
.page-about .sites-grid .media-frame {
  margin: 0;
}

/* ---------- 阅读方式 ---------- */
.page-about .read-strip {
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: 40px 0 44px;
  background: linear-gradient(180deg, rgba(16, 31, 26, 0.55), transparent);
}

.page-about .read-grid {
  margin-top: 26px;
}

.page-about .read-cell {
  padding: 18px 0 4px;
  border-top: 1px solid var(--line);
}

.page-about .read-cell h3 {
  margin: 12px 0 8px;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.01em;
}

.page-about .read-cell p {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--gray);
}

/* ---------- 索引轨骨架 ---------- */
.page-about .index-shell {
  display: grid;
  gap: var(--about-gap);
  padding-top: 44px;
}

.page-about .index-rail {
  padding-bottom: 18px;
  border-bottom: 1px solid var(--line);
}

.page-about .rail-title {
  margin: 0 0 12px;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.1em;
  color: var(--gray);
}

.page-about .rail-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .rail-list .index-link {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--gray);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .rail-list .index-link:hover,
.page-about .rail-list .index-link[aria-current="true"] {
  color: var(--lime);
  border-bottom-color: var(--lime);
}

.page-about .rail-note {
  margin: 16px 0 0;
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--turf);
}

.page-about .index-body {
  min-width: 0;
  display: grid;
  gap: 56px;
}

.page-about .index-body .section {
  min-width: 0;
}

.page-about .section-head {
  max-width: 74ch;
}

.page-about .section-title {
  font-size: clamp(24px, 4.4vw, 38px);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.01em;
  margin: 10px 0 12px;
}

.page-about .section-note {
  font-size: 14px;
  line-height: 1.75;
  color: var(--gray);
}

/* ---------- 版本时间轴 ---------- */
.page-about .v-track {
  position: relative;
  margin-top: 30px;
  padding-left: 20px;
}

.page-about .v-track::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(180deg, var(--lime), var(--turf) 48%, rgba(31, 107, 69, 0) 100%);
  transform: rotate(1.6deg);
  transform-origin: top center;
}

.page-about .v-item {
  display: grid;
  grid-template-columns: 58px minmax(0, 1fr);
  gap: 14px;
  padding: 24px 0;
  border-bottom: 1px solid var(--line);
  transition: transform var(--dur) var(--ease);
}

.page-about .v-item:first-child {
  border-top: 1px solid var(--line);
}

.page-about .v-num {
  font-size: clamp(30px, 6vw, 56px);
  font-weight: 200;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--turf);
  transition: color var(--dur) var(--ease);
}

.page-about .v-item:hover .v-num {
  color: var(--lime);
}

.page-about .v-title {
  margin: 4px 0 8px;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.01em;
}

.page-about .v-body p {
  margin: 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--gray);
}

.page-about .v-list {
  margin: 12px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 6px;
  font-size: 13px;
  color: var(--mint);
}

.page-about .v-list li {
  position: relative;
  padding-left: 16px;
}

.page-about .v-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.75em;
  width: 8px;
  height: 1px;
  background: var(--lime);
}

.page-about .v-figure {
  margin-top: 34px;
}

/* ---------- 场馆索引 ---------- */
.page-about .sites-grid {
  display: grid;
  gap: 24px;
  margin-top: 26px;
}

.page-about .sites-text p {
  margin: 0 0 18px;
  font-size: 14px;
  line-height: 1.78;
  color: var(--gray);
}

.page-about .term-list {
  margin: 0;
  border-top: 1px solid var(--line);
}

.page-about .term-row {
  display: grid;
  gap: 4px;
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .term-row dt {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--lime);
}

.page-about .term-row dd {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--gray);
}

/* ---------- 核定方法 ---------- */
.page-about .method-flow {
  display: block;
  width: 100%;
  height: auto;
  margin: 30px 0 10px;
}

.page-about .method-flow .flow-label text {
  font-family: var(--font-sans);
  font-size: 12px;
  letter-spacing: 0.08em;
  fill: var(--gray);
}

.page-about .method-steps {
  margin-top: 22px;
  border-top: 1px solid var(--line);
}

.page-about .method-step {
  border-bottom: 1px solid var(--line);
  padding: 16px 0;
}

.page-about .method-step summary {
  display: flex;
  align-items: baseline;
  gap: 14px;
  cursor: pointer;
  list-style: none;
  font-size: 15px;
  font-weight: 600;
  color: var(--mist);
}

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

.page-about .method-step summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  color: var(--turf);
  transition: color var(--dur) var(--ease);
}

.page-about .method-step[open] summary::after {
  content: "−";
  color: var(--lime);
}

.page-about .method-step summary:hover {
  color: var(--lime);
}

.page-about .step-idx {
  font-size: 12px;
  color: var(--mint);
}

.page-about .step-body {
  padding: 12px 0 2px 30px;
}

.page-about .step-body p {
  margin: 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--gray);
}

.page-about .boundary-box {
  margin-top: 28px;
  padding: 18px 20px;
  border-left: 2px solid var(--flare);
  background: linear-gradient(90deg, rgba(255, 90, 54, 0.08), transparent 70%);
}

.page-about .boundary-box p {
  margin: 10px 0 0;
  font-size: 13px;
  line-height: 1.75;
  color: var(--gray);
}

/* ---------- 团队与节奏 ---------- */
.page-about .team-panel {
  margin-top: 26px;
  padding: clamp(18px, 3vw, 30px);
  border: 1px solid var(--line);
  background: linear-gradient(160deg, var(--panel), rgba(14, 26, 22, 0.9));
}

.page-about .team-panel .stat-num {
  display: block;
  font-size: clamp(34px, 7vw, 54px);
  font-weight: 200;
  line-height: 1;
  color: var(--lime);
}

.page-about .team-panel .stat-label {
  display: block;
  margin-top: 8px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--gray);
}

.page-about .team-note {
  margin: 22px 0 0;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  font-size: 14px;
  line-height: 1.78;
  color: var(--gray);
}

.page-about .cadence {
  margin-top: 30px;
}

.page-about .cadence-item {
  display: grid;
  gap: 6px;
  padding: 14px 0;
  border-top: 1px solid var(--line);
}

.page-about .cadence-item:last-child {
  border-bottom: 1px solid var(--line);
}

.page-about .cadence-when {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--mint);
}

.page-about .cadence-item p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--gray);
}

/* ---------- 纠错循环 ---------- */
.page-about .loop-grid {
  margin-top: 26px;
}

.page-about .loop-panel {
  border: 1px solid var(--line);
  background: rgba(16, 31, 26, 0.7);
}

.page-about .loop-steps {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 12px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--gray);
}

.page-about .loop-steps .num {
  color: var(--lime);
  margin-right: 8px;
}

.page-about .loop-panel .panel-body p {
  margin: 0 0 14px;
  font-size: 14px;
  line-height: 1.78;
  color: var(--gray);
}

.page-about .loop-contact {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
}

.page-about .loop-contact .mono {
  color: var(--mist);
  font-size: 13px;
  word-break: break-all;
}

.page-about .loop-links {
  margin: 0;
}

.page-about .loop-links .index-link,
.page-about .next-links .index-link {
  color: var(--mint);
  font-size: 13px;
  letter-spacing: 0.06em;
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  padding-bottom: 2px;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .loop-links .index-link:hover,
.page-about .next-links .index-link:hover {
  color: var(--lime);
  border-bottom-color: var(--lime);
}

/* ---------- 数据边界与延伸阅读 ---------- */
.page-about .boundary-note {
  margin-top: 24px;
  padding: 22px 20px;
  border: 1px solid var(--line);
  background: linear-gradient(200deg, rgba(31, 107, 69, 0.22), rgba(10, 16, 32, 0.4));
}

.page-about .boundary-note p {
  margin: 0 0 14px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .boundary-note p:last-child {
  margin-bottom: 0;
  color: var(--gray);
}

.page-about .next-links {
  margin-top: 34px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.page-about .next-links ul {
  display: grid;
  gap: 12px;
  margin: 14px 0 0;
  padding: 0;
  list-style: none;
}

/* ---------- 平板与桌面 ---------- */
@media (min-width: 700px) {
  .page-about .term-row {
    grid-template-columns: 1fr 1.6fr;
    gap: 18px;
    align-items: baseline;
  }

  .page-about .cadence-item {
    grid-template-columns: 168px minmax(0, 1fr);
    gap: 22px;
    align-items: baseline;
  }

  .page-about .next-links ul {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px 28px;
  }
}

@media (min-width: 960px) {
  .page-about .about-hero__grid {
    grid-template-columns: 5fr 7fr;
    gap: 52px;
    align-items: center;
    padding: 48px 0 66px;
  }

  .page-about .sites-grid {
    grid-template-columns: 5fr 6fr;
    gap: 40px;
    align-items: start;
  }

  .page-about .v-track {
    padding-left: 26px;
  }

  .page-about .v-item {
    grid-template-columns: 92px minmax(0, 1fr);
    gap: 26px;
    padding: 32px 0;
  }

  .page-about .v-item:nth-child(even) {
    margin-left: 54px;
  }

  .page-about .v-item:nth-child(odd) {
    margin-right: 54px;
  }

  .page-about .method-steps,
  .page-about .cadence,
  .page-about .team-panel {
    max-width: 900px;
  }
}

@media (min-width: 1024px) {
  .page-about .index-shell {
    grid-template-columns: var(--rail-w) minmax(0, 1fr);
    gap: 52px;
    align-items: start;
  }

  .page-about .index-rail {
    position: sticky;
    top: 108px;
    padding-bottom: 0;
    border-bottom: 0;
    border-left: 1px solid var(--line);
    padding-left: 16px;
  }

  .page-about .rail-list {
    flex-direction: column;
    gap: 12px;
  }

  .page-about .rail-list .index-link {
    display: block;
    padding: 2px 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .v-item,
  .page-about .v-num,
  .page-about .rail-list .index-link,
  .page-about .loop-links .index-link,
  .page-about .next-links .index-link {
    transition: none;
  }
}