.page-about {
  --about-rail-w: 172px;
  --about-num-size: clamp(32px, 5.4vw, 58px);
  --about-grid-line: rgba(44, 56, 115, .28);
  color: var(--mist-050);
  background-color: var(--ink-900);
  background-image:
    linear-gradient(var(--about-grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--about-grid-line) 1px, transparent 1px);
  background-size: 34px 34px;
  padding-bottom: clamp(48px, 8vw, 96px);
}

.page-about .breadcrumb {
  padding-top: clamp(20px, 3vw, 32px);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding: clamp(28px, 5vw, 56px) 0 clamp(36px, 6vw, 72px);
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(24px, 4vw, 44px);
  align-items: end;
}

@media (min-width: 940px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.08fr) minmax(0, .92fr);
    gap: clamp(32px, 4vw, 56px);
  }
}

.page-about .about-hero h1 {
  margin: 14px 0 20px;
  font-size: clamp(32px, 5.6vw, 66px);
  font-weight: 300;
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--mist-050);
}

.page-about .about-hero__intro {
  margin: 0;
  max-width: 48ch;
  font-size: 16px;
  line-height: 1.78;
  color: var(--slate-300);
}

.page-about .about-hero__facts {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .about-hero__facts li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 6px 14px;
  align-items: baseline;
  padding: 11px 0;
  border-top: 1px solid var(--line-600);
  font-size: 14px;
  line-height: 1.66;
  color: var(--mist-050);
}

.page-about .about-hero__facts li:last-child {
  border-bottom: 1px solid var(--line-600);
}

.page-about .about-hero__key {
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--teal-400);
}

/* ---------- 图片框微调 ---------- */
.page-about .media-frame {
  margin: 0;
  background: var(--ink-800);
}

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

.page-about .media-frame__caption {
  padding: 10px 14px;
  font-size: 12px;
  line-height: 1.6;
  letter-spacing: .02em;
  color: var(--slate-300);
}

/* ---------- 主体两栏 ---------- */
.page-about .about-body {
  display: grid;
  gap: clamp(28px, 4vw, 44px);
}

@media (min-width: 1040px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: 56px;
    align-items: start;
  }
}

/* ---------- 左侧刻度带 ---------- */
.page-about .about-rail__label {
  margin: 0 0 10px;
  color: var(--slate-300);
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 6px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-rail__link {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  padding: 9px 12px;
  border: 2px solid var(--line-600);
  border-radius: var(--radius);
  background: var(--ink-800);
  color: var(--slate-300);
  font-size: 13px;
  line-height: 1.3;
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--mist-050);
  border-color: var(--teal-400);
  background: var(--ink-700);
  outline: none;
}

.page-about .about-rail__link:focus-visible {
  box-shadow: 0 0 0 2px var(--teal-400);
}

.page-about .about-rail__num {
  font-size: 11px;
  letter-spacing: .08em;
  color: var(--orange-500);
}

@media (min-width: 1040px) {
  .page-about .about-rail {
    position: sticky;
    top: 104px;
    align-self: start;
  }

  .page-about .about-rail__list {
    flex-direction: column;
    gap: 6px;
    overflow: visible;
    padding-bottom: 0;
    border-left: 2px solid var(--line-600);
    padding-left: 14px;
  }

  .page-about .about-rail__link {
    width: 100%;
    border-color: transparent;
    background: transparent;
    padding: 8px 10px;
  }

  .page-about .about-rail__link:hover,
  .page-about .about-rail__link:focus-visible {
    border-color: var(--line-600);
    background: var(--ink-700);
  }
}

/* ---------- 章节 ---------- */
.page-about .about-chapter {
  scroll-margin-top: 112px;
}

.page-about .about-chapter + .about-chapter {
  margin-top: clamp(40px, 6vw, 72px);
  padding-top: clamp(36px, 5vw, 56px);
  border-top: 2px solid var(--line-600);
}

.page-about .about-chapter__head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 6px 18px;
  align-items: start;
  margin-bottom: 22px;
}

.page-about .about-chapter__num {
  font-size: var(--about-num-size);
  font-weight: 300;
  line-height: .95;
  letter-spacing: -0.02em;
  color: var(--teal-400);
}

.page-about .about-chapter__head h2 {
  margin: 4px 0 0;
  font-size: clamp(22px, 3.1vw, 32px);
  font-weight: 700;
  line-height: 1.28;
  letter-spacing: -0.01em;
  color: var(--mist-050);
}

.page-about .about-chapter__kicker {
  margin: 8px 0 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--slate-300);
}

.page-about .about-chapter__body p {
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.78;
  color: var(--slate-300);
}

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

.page-about .about-chapter__tail {
  margin: 22px 0 0;
  padding-left: 16px;
  border-left: 8px solid var(--teal-400);
  font-size: 14px;
  line-height: 1.76;
  color: var(--slate-300);
}

.page-about .about-chapter__tail a {
  color: var(--teal-400);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-chapter__tail a:hover,
.page-about .about-chapter__tail a:focus-visible {
  color: var(--mist-050);
}

.page-about .about-chapter__figure {
  margin: 0 0 22px;
}

/* ---------- 版本卡片 ---------- */
.page-about .version-list {
  display: grid;
  gap: 12px;
}

.page-about .version-card {
  border: 2px solid var(--line-600);
  border-radius: var(--radius);
  background: var(--ink-800);
  box-shadow: var(--shadow-soft);
  transition: border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}

.page-about .version-card[open] {
  border-color: var(--line-600);
  box-shadow: var(--shadow-hard);
}

.page-about .version-card__head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  gap: 8px 14px;
  align-items: baseline;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
  transition: background-color var(--dur) var(--ease);
}

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

.page-about .version-card__head:hover {
  background: var(--ink-700);
}

.page-about .version-card__head:focus-visible {
  outline: 2px solid var(--teal-400);
  outline-offset: -2px;
}

.page-about .version-card__tag {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: .06em;
  color: var(--orange-500);
  border: 2px solid var(--orange-500);
  border-radius: var(--radius);
  padding: 2px 7px;
  line-height: 1.3;
}

.page-about .version-card__title {
  font-size: 16px;
  font-weight: 500;
  line-height: 1.45;
  color: var(--mist-050);
}

.page-about .version-card__toggle {
  font-family: var(--font-mono);
  font-size: 17px;
  line-height: 1;
  color: var(--teal-400);
}

.page-about .version-card__toggle::before {
  content: "+";
}

.page-about .version-card[open] .version-card__toggle::before {
  content: "−";
}

.page-about .version-card__body {
  padding: 16px 18px 20px;
  border-top: 2px solid var(--line-600);
}

.page-about .version-card__body p {
  margin: 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--slate-300);
}

.page-about .version-card__list {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 8px;
}

.page-about .version-card__list li {
  position: relative;
  padding-left: 18px;
  font-size: 14px;
  line-height: 1.68;
  color: var(--mist-050);
}

.page-about .version-card__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 8px;
  height: 2px;
  background: var(--teal-400);
}

/* ---------- 团队 ---------- */
.page-about .about-team {
  display: grid;
  gap: 12px;
}

@media (min-width: 880px) {
  .page-about .about-team {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.page-about .team-card {
  border: 2px solid var(--line-600);
  border-left: 8px solid var(--line-600);
  border-radius: var(--radius);
  background: var(--ink-700);
  padding: 20px 18px 22px;
  box-shadow: var(--shadow-soft);
  transition: transform var(--dur) var(--ease), box-shadow var(--dur) var(--ease), border-left-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .team-card:hover,
.page-about .team-card:focus-within {
  transform: translateY(-2px);
  border-left-color: var(--teal-400);
  background: var(--ink-800);
  box-shadow: var(--shadow-hard);
}

.page-about .team-card__count {
  display: block;
  font-size: clamp(42px, 6vw, 60px);
  font-weight: 300;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--teal-400);
}

.page-about .team-card__title {
  margin: 12px 0 0;
  font-size: 17px;
  font-weight: 500;
  line-height: 1.4;
  color: var(--mist-050);
}

.page-about .team-card__desc {
  margin: 10px 0 0;
  font-size: 14px;
  line-height: 1.76;
  color: var(--slate-300);
}

.page-about .about-team__figure {
  margin: 8px 0 0;
  width: 100%;
  max-width: 620px;
  justify-self: center;
}

@media (min-width: 880px) {
  .page-about .about-team__figure {
    grid-column: 1 / -1;
  }
}

/* ---------- 规模 ---------- */
.page-about .about-scale {
  display: grid;
  gap: 24px;
}

@media (min-width: 720px) {
  .page-about .about-scale {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 28px 20px;
  }
}

@media (min-width: 1040px) {
  .page-about .about-scale {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .about-scale__item {
  padding-top: 16px;
  border-top: 2px solid var(--teal-400);
}

.page-about .about-scale__num {
  display: block;
  font-size: clamp(34px, 5.2vw, 48px);
  font-weight: 300;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--mist-050);
}

.page-about .about-scale__label {
  display: block;
  margin-top: 10px;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: .08em;
  color: var(--orange-500);
}

.page-about .about-scale__note {
  margin: 8px 0 0;
  font-size: 13px;
  line-height: 1.74;
  color: var(--slate-300);
}

/* ---------- 路线图 ---------- */
.page-about .about-roadmap {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .about-roadmap__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 4px 18px;
  align-items: start;
  padding: 18px 20px;
  border: 2px solid var(--line-600);
  border-radius: var(--radius);
  background: var(--ink-800);
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .about-roadmap__item:hover {
  border-color: var(--teal-400);
  background: var(--ink-700);
}

.page-about .about-roadmap__num {
  grid-row: span 2;
  font-size: 22px;
  font-weight: 300;
  line-height: 1.2;
  color: var(--orange-500);
}

.page-about .about-roadmap__item h3 {
  margin: 0;
  font-size: 16px;
  font-weight: 500;
  line-height: 1.45;
  color: var(--mist-050);
}

.page-about .about-roadmap__item p {
  margin: 6px 0 0;
  font-size: 14px;
  line-height: 1.74;
  color: var(--slate-300);
}

/* ---------- 收尾 ---------- */
.page-about .about-cta {
  margin-top: clamp(48px, 7vw, 84px);
  padding: clamp(24px, 4vw, 36px);
  border: 2px solid var(--paper-050);
  border-radius: var(--radius);
  background: var(--ink-800);
  box-shadow: var(--shadow-hard);
}

.page-about .about-cta__title {
  margin: 0;
  font-size: clamp(20px, 2.8vw, 27px);
  font-weight: 700;
  line-height: 1.32;
  letter-spacing: -0.01em;
  color: var(--mist-050);
}

.page-about .about-cta__text {
  margin: 12px 0 0;
  max-width: 54ch;
  font-size: 14px;
  line-height: 1.78;
  color: var(--slate-300);
}

.page-about .about-cta__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}