.page-about {
  background: var(--c-paper);
  color: var(--c-ink);
  font-family: var(--font-body);
  overflow-x: hidden;
}

/* ---------- 首屏 ---------- */
.page-about__hero {
  position: relative;
  isolation: isolate;
  padding: calc(var(--header-h) + 56px) 0 72px;
  background:
    radial-gradient(90% 130% at 6% -18%, #14507A 0%, rgba(20, 80, 122, 0) 58%),
    radial-gradient(70% 100% at 102% 4%, rgba(232, 180, 74, 0.24) 0%, rgba(232, 180, 74, 0) 62%),
    var(--c-deep);
  color: var(--c-paper);
  overflow: hidden;
}

.page-about__hero::before {
  content: "";
  position: absolute;
  left: -20%;
  right: -20%;
  bottom: -58%;
  height: 78%;
  background:
    radial-gradient(closest-side, rgba(232, 180, 74, 0.20), transparent 72%),
    radial-gradient(closest-side at 32% 42%, rgba(47, 168, 143, 0.16), transparent 70%);
  filter: blur(8px);
  pointer-events: none;
  z-index: -1;
}

.page-about .breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin: 0 0 30px;
  padding: 0;
  list-style: none;
  font-size: 13px;
  letter-spacing: 0.06em;
}

.page-about .breadcrumb li {
  display: flex;
  align-items: center;
  gap: 10px;
}

.page-about .breadcrumb li + li::before {
  content: "›";
  color: rgba(232, 180, 74, 0.7);
}

.page-about .breadcrumb a {
  color: rgba(251, 246, 236, 0.7);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .breadcrumb a:hover,
.page-about .breadcrumb a:focus-visible {
  color: var(--c-gold);
  border-bottom-color: var(--c-gold);
}

.page-about .breadcrumb [aria-current="page"] {
  color: var(--c-gold);
}

.page-about__plate {
  background: rgba(232, 180, 74, 0.14);
  border-color: rgba(232, 180, 74, 0.5);
  color: var(--c-gold);
}

.page-about .page-about__h1 {
  margin: 20px 0 0;
  max-width: 15ch;
  font-family: var(--font-display);
  font-size: clamp(30px, 7.4vw, 54px);
  line-height: 1.22;
  letter-spacing: 0.04em;
  color: var(--c-paper);
}

.page-about__hero-lede {
  margin: 22px 0 0;
  max-width: 46ch;
  font-size: 16px;
  line-height: 1.9;
  color: rgba(251, 246, 236, 0.84);
}

.page-about__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px 26px;
  margin: 44px 0 0;
  padding: 26px 0 0;
  border-top: 1px solid rgba(232, 180, 74, 0.28);
}

.page-about__stat dt {
  font-size: 12px;
  letter-spacing: 0.18em;
  color: rgba(251, 246, 236, 0.6);
}

.page-about__stat dd {
  margin: 8px 0 0;
  font-family: var(--font-display);
  font-size: clamp(22px, 4.6vw, 30px);
  line-height: 1.15;
  color: var(--c-gold);
  letter-spacing: 0.03em;
}

.page-about__hero-ann {
  position: absolute;
  right: 12px;
  bottom: 26px;
  color: rgba(232, 180, 74, 0.7);
  writing-mode: vertical-rl;
}

/* ---------- 章节通用 ---------- */
.page-about__section {
  position: relative;
  padding: 68px 0 76px;
}

.page-about__section .section-head {
  margin-bottom: 34px;
}

.page-about .page-about__h2 {
  font-family: var(--font-display);
  font-size: clamp(24px, 5.2vw, 38px);
  line-height: 1.3;
  letter-spacing: 0.03em;
  margin: 14px 0 0;
  color: var(--c-ink);
}

.page-about .lead,
.page-about .lede {
  max-width: 56ch;
}

.page-about__section .lede {
  margin-top: 16px;
  font-size: 16px;
  line-height: 1.9;
  color: var(--c-ink-soft);
}

.page-about__fig {
  margin: 0 0 42px;
  border: 1px solid var(--c-line-soft);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-1);
}

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

/* ---------- 发展轴 ---------- */
.page-about__timeline {
  background: var(--c-paper);
}

.page-about__stages {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 20px;
}

.page-about__dot {
  display: none;
}

.page-about__stage-card {
  padding: 26px 22px 24px;
  border: 1px solid var(--c-line);
  background: #fff;
  transition: transform var(--dur) var(--ease), box-shadow var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about__stage-card:hover,
.page-about__stage-card:focus-within {
  transform: translateY(-2px);
  border-color: var(--c-gold);
  box-shadow: var(--shadow-2);
}

.page-about__stage-year {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-size: clamp(30px, 6.4vw, 44px);
  line-height: 1;
  letter-spacing: 0.06em;
  color: var(--c-gold-deep);
  padding-bottom: 10px;
  border-bottom: 1px solid var(--c-line-gold);
}

.page-about__stage-card .card-title {
  margin: 0 0 10px;
  font-size: 18px;
  line-height: 1.5;
  color: var(--c-ink);
}

.page-about__stage-card p {
  margin: 0;
  font-size: 15px;
  line-height: 1.9;
  color: var(--c-ink-soft);
}

/* ---------- 分类体系 ---------- */
.page-about__classes {
  background: var(--c-mist);
}

.page-about__class-intro {
  align-items: start;
  margin-bottom: 40px;
}

.page-about__class-fig {
  margin: 0;
  border: 1px solid var(--c-line-soft);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-1);
  background: #fff;
}

.page-about__class-note {
  position: relative;
  padding-top: 6px;
}

.page-about__note-ann {
  display: block;
  margin-bottom: 16px;
  color: var(--c-gold-deep);
  writing-mode: horizontal-tb;
}

.page-about__class-note p {
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--c-ink-soft);
}

.page-about .page-about__class-note .muted {
  font-size: 14px;
  color: var(--c-ink-soft);
}

.page-about__class-note a,
.page-about__dual-aside a,
.page-about__return-note a,
.page-about .muted a {
  color: var(--c-red);
  text-decoration: none;
  border-bottom: 1px solid rgba(200, 16, 46, 0.35);
  transition: border-color var(--dur) var(--ease);
}

.page-about__class-note a:hover,
.page-about__dual-aside a:hover,
.page-about__return-note a:hover,
.page-about .muted a:hover {
  border-bottom-color: var(--c-red);
}

.page-about__class-list {
  display: grid;
  gap: 12px;
}

.page-about .page-about__class {
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  background: #fff;
  box-shadow: var(--shadow-1);
  transition: border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.page-about .page-about__class[open] {
  border-color: var(--c-gold);
  box-shadow: var(--shadow-2);
}

.page-about .page-about__class summary {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 14px;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-body);
}

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

.page-about .page-about__class summary::after {
  content: "+";
  font-family: var(--font-display);
  font-size: 20px;
  line-height: 1;
  color: var(--c-gold-deep);
  transition: color var(--dur) var(--ease);
}

.page-about .page-about__class[open] summary::after {
  content: "−";
  color: var(--c-red);
}

.page-about .page-about__class summary:focus-visible {
  outline: 2px solid var(--c-gold);
  outline-offset: -4px;
}

.page-about__class-idx {
  font-family: var(--font-display);
  font-size: 15px;
  letter-spacing: 0.08em;
  color: var(--c-gold-deep);
  padding-top: 2px;
}

.page-about__class-main {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px;
}

.page-about__class-name {
  font-family: var(--font-display);
  font-size: 17px;
  letter-spacing: 0.04em;
  color: var(--c-ink);
}

.page-about__class-tag {
  font-size: 12px;
  letter-spacing: 0.14em;
  padding: 2px 9px;
  border-radius: 999px;
  color: var(--c-mid);
  background: rgba(20, 80, 122, 0.10);
  border: 1px solid rgba(20, 80, 122, 0.22);
}

.page-about .page-about__class .spec-body {
  padding: 0 18px 20px 50px;
}

.page-about .page-about__class .spec-body p {
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--c-ink-soft);
}

.page-about__class-meta {
  display: grid;
  gap: 8px;
  margin: 0;
  padding-top: 12px;
  border-top: 1px solid var(--c-line-soft);
}

.page-about__class-meta div {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  font-size: 13px;
}

.page-about__class-meta dt {
  min-width: 70px;
  color: var(--c-ink-faint);
  letter-spacing: 0.08em;
}

.page-about__class-meta dd {
  margin: 0;
  color: var(--c-ink);
}

/* ---------- 双端 ---------- */
.page-about__dual {
  background: var(--c-paper);
}

.page-about__dual-grid {
  align-items: start;
}

.page-about__dual-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about__dual-list li {
  display: grid;
  gap: 6px;
  padding: 20px 0;
  border-bottom: 1px solid var(--c-line-soft);
}

.page-about__dual-list li:first-child {
  padding-top: 0;
}

.page-about__dual-k {
  font-family: var(--font-display);
  font-size: 16px;
  letter-spacing: 0.06em;
  color: var(--c-mid);
}

.page-about__dual-v {
  font-size: 15px;
  line-height: 1.9;
  color: var(--c-ink-soft);
}

.page-about__dual-aside {
  padding: 24px 20px;
  border: 1px solid var(--c-line);
  background: var(--c-mist);
}

.page-about__dual-aside p {
  margin: 14px 0 0;
  font-size: 14px;
  line-height: 1.9;
  color: var(--c-ink-soft);
}

.page-about__dual-aside .plate {
  margin: 0;
  background: transparent;
  border-color: var(--c-line);
  color: var(--c-gold-deep);
}

/* ---------- 回归额度 ---------- */
.page-about__return {
  background:
    radial-gradient(85% 130% at 92% -10%, rgba(20, 80, 122, 0.9) 0%, rgba(20, 80, 122, 0) 62%),
    radial-gradient(60% 100% at 4% 110%, rgba(200, 16, 46, 0.30) 0%, rgba(200, 16, 46, 0) 64%),
    var(--c-deep);
  color: var(--c-paper);
}

.page-about .section-head--deep .plate {
  background: rgba(232, 180, 74, 0.14);
  border-color: rgba(232, 180, 74, 0.5);
  color: var(--c-gold);
}

.page-about .section-head--deep .page-about__h2 {
  color: var(--c-paper);
}

.page-about .section-head--deep .lede {
  color: rgba(251, 246, 236, 0.78);
}

.page-about__tiers {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 16px;
}

.page-about__tier {
  position: relative;
  padding: 22px 20px 20px;
  border: 1px solid rgba(232, 180, 74, 0.34);
  border-radius: var(--radius);
  background: rgba(11, 42, 69, 0.52);
  transition: transform var(--dur) var(--ease), border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}

.page-about__tier:hover,
.page-about__tier:focus-within {
  transform: translateY(-2px);
  border-color: rgba(232, 180, 74, 0.86);
  box-shadow: 0 22px 44px -28px rgba(0, 0, 0, 0.85);
}

.page-about__tier:nth-child(2) {
  border-color: rgba(232, 180, 74, 0.5);
}

.page-about__tier:nth-child(3) {
  border-color: rgba(200, 16, 46, 0.6);
  background: rgba(200, 16, 46, 0.16);
}

.page-about__tier-days {
  display: flex;
  align-items: baseline;
  gap: 8px;
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-size: clamp(34px, 7vw, 48px);
  line-height: 1;
  letter-spacing: 0.04em;
  color: var(--c-gold);
}

.page-about__tier-days span {
  font-family: var(--font-body);
  font-size: 13px;
  letter-spacing: 0.16em;
  color: rgba(251, 246, 236, 0.72);
}

.page-about__tier-desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.85;
  color: rgba(251, 246, 236, 0.78);
}

.page-about__return-steps {
  margin-top: 46px;
  padding-top: 30px;
  border-top: 1px solid rgba(232, 180, 74, 0.28);
}

.page-about__sub {
  margin: 0 0 20px;
  font-family: var(--font-display);
  font-size: 20px;
  letter-spacing: 0.05em;
  color: var(--c-paper);
}

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

.page-about__steps li {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 14px;
  align-items: start;
  font-size: 15px;
  line-height: 1.85;
  color: rgba(251, 246, 236, 0.82);
}

.page-about__step-idx {
  font-family: var(--font-display);
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--c-deep);
  background: var(--c-gold);
  border-radius: 999px;
  padding: 2px 9px;
  margin-top: 3px;
  white-space: nowrap;
}

.page-about__return-note {
  margin: 24px 0 0;
  font-size: 14px;
  color: rgba(251, 246, 236, 0.7);
}

.page-about__return-note a {
  color: var(--c-gold);
  border-bottom-color: rgba(232, 180, 74, 0.45);
}

.page-about__return-note a:hover {
  border-bottom-color: var(--c-gold);
}

/* ---------- 服务能力 ---------- */
.page-about__service {
  background: var(--c-mist);
}

.page-about__fig--service {
  margin-top: 0;
}

.page-about__service-grid {
  display: grid;
  gap: 16px;
}

.page-about__service-card {
  padding: 24px 20px 22px;
  background: var(--c-paper);
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-1);
  transition: transform var(--dur) var(--ease), box-shadow var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about__service-card:hover,
.page-about__service-card:focus-within {
  transform: translateY(-2px);
  border-color: var(--c-gold);
  box-shadow: var(--shadow-2);
}

.page-about__service-num {
  margin: 0 0 12px;
  font-family: var(--font-display);
  font-size: clamp(40px, 8vw, 54px);
  line-height: 1;
  letter-spacing: 0.04em;
  color: var(--c-gold-deep);
  padding-bottom: 10px;
  border-bottom: 1px solid var(--c-line-gold);
}

.page-about__service-card .card-title {
  margin: 0 0 10px;
  font-size: 17px;
  line-height: 1.5;
  color: var(--c-ink);
}

.page-about__service-card p:last-child {
  margin: 0;
  font-size: 14px;
  line-height: 1.85;
  color: var(--c-ink-soft);
}

.page-about__service-facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 20px 28px;
  margin: 40px 0 0;
  padding: 24px 0 0;
  border-top: 1px solid var(--c-line);
}

.page-about__service-facts dt {
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--c-ink-faint);
}

.page-about__service-facts dd {
  margin: 8px 0 0;
  font-family: var(--font-display);
  font-size: 22px;
  letter-spacing: 0.04em;
  color: var(--c-mid);
}

/* ---------- 运营主体 ---------- */
.page-about__operator {
  background: var(--c-paper);
  padding-bottom: 88px;
}

.page-about__operator-grid {
  align-items: start;
}

.page-about__operator p {
  font-size: 15px;
  line-height: 1.9;
  color: var(--c-ink-soft);
}

.page-about__operator-list {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
}

.page-about__operator-list li {
  display: grid;
  gap: 4px;
  padding: 13px 0;
  border-bottom: 1px solid var(--c-line-soft);
  font-size: 14px;
  color: var(--c-ink);
}

.page-about__operator-list span:first-child {
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--c-ink-faint);
}

.page-about__operator-list a {
  color: var(--c-red);
  text-decoration: none;
  border-bottom: 1px solid rgba(200, 16, 46, 0.32);
  word-break: break-all;
}

.page-about__operator-list a:hover {
  border-bottom-color: var(--c-red);
}

.page-about__operator-aside {
  display: grid;
  gap: 18px;
}

.page-about__seal {
  padding: 24px 20px;
  border: 1px solid var(--c-line);
  background: #fff;
}

.page-about__seal-label {
  margin: 0 0 6px;
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--c-ink-faint);
}

.page-about__seal-label + .page-about__seal-value {
  margin-bottom: 20px;
}

.page-about__seal-value {
  margin: 0;
  font-family: var(--font-display);
  font-size: 32px;
  line-height: 1.2;
  letter-spacing: 0.08em;
  color: var(--c-red);
}

.page-about__seal-value--sm {
  font-size: 17px;
  letter-spacing: 0.05em;
  color: var(--c-gold-deep);
}

.page-about__operator-aside .muted {
  margin: 0;
  font-size: 13px;
  line-height: 1.85;
  color: var(--c-ink-soft);
}

/* ---------- 断点 ---------- */
@media (min-width: 640px) {
  .page-about__stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about__class-list {
    gap: 14px;
  }

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

  .page-about__operator-list li {
    grid-template-columns: 108px 1fr;
    align-items: baseline;
    gap: 14px;
  }

  .page-about__operator-list span:first-child {
    padding-top: 2px;
  }
}

@media (min-width: 860px) {
  .page-about__hero {
    padding: calc(var(--header-h) + 78px) 0 96px;
  }

  .page-about__hero-lede {
    font-size: 17px;
  }

  .page-about__section {
    padding: 88px 0 96px;
  }

  .page-about__fig {
    margin-bottom: 52px;
  }

  .page-about__stages {
    gap: 26px;
  }

  .page-about__stages::before {
    content: "";
    position: absolute;
    left: 14px;
    top: 14px;
    bottom: 14px;
    width: 1px;
    background: linear-gradient(180deg, rgba(232, 180, 74, 0.8) 0%, rgba(232, 180, 74, 0.45) 60%, rgba(232, 180, 74, 0.06) 100%);
  }

  .page-about__stage {
    position: relative;
    padding-left: 62px;
  }

  .page-about__dot {
    display: block;
    position: absolute;
    left: 8px;
    top: 28px;
    width: 13px;
    height: 13px;
    border-radius: 50%;
    background: var(--c-paper);
    border: 2px solid var(--c-gold);
    transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease), transform var(--dur) var(--ease);
  }

  .page-about__stage:hover .page-about__dot,
  .page-about__stage:focus-within .page-about__dot {
    background: var(--c-red);
    border-color: var(--c-red);
    transform: scale(1.2);
  }

  .page-about__stage-card {
    padding: 30px 30px 28px;
  }

  .page-about__class-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px 20px;
  }

  .page-about .page-about__class summary {
    padding: 18px 22px;
  }

  .page-about .page-about__class .spec-body {
    padding: 0 22px 22px 58px;
  }

  .page-about__tiers {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 20px;
  }

  .page-about__tier {
    padding: 26px 24px 24px;
  }

  .page-about__steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px 28px;
  }

  .page-about__service-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about__dual-list li {
    grid-template-columns: 108px 1fr;
    gap: 20px;
    align-items: baseline;
  }

  .page-about__dual-k {
    padding-top: 2px;
  }
}

@media (min-width: 1100px) {
  .page-about__class-list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about__service-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about__stage-card,
  .page-about__tier,
  .page-about__service-card,
  .page-about__dot,
  .page-about .page-about__class {
    transition: none;
  }

  .page-about__stage-card:hover,
  .page-about__stage-card:focus-within,
  .page-about__tier:hover,
  .page-about__tier:focus-within,
  .page-about__service-card:hover,
  .page-about__service-card:focus-within {
    transform: none;
  }
}