.page-about {
  --about-gap: clamp(24px, 3.4vw, 56px);
  --about-block-gap: clamp(36px, 5vw, 72px);
  background: var(--sand);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.85;
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */
.page-about .section.about-hero {
  position: relative;
  padding-top: clamp(24px, 4vw, 48px);
  padding-bottom: clamp(30px, 4.6vw, 60px);
  overflow: hidden;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  top: -12%;
  right: -14%;
  width: min(620px, 62vw);
  height: min(460px, 52vw);
  background: linear-gradient(135deg, var(--clay) 0%, var(--clay-deep) 100%);
  clip-path: polygon(20% 0, 100% 0, 100% 100%, 0 70%);
  opacity: .16;
  pointer-events: none;
}

.page-about .about-hero__inner {
  position: relative;
  z-index: 1;
}

.page-about .about-hero__title {
  margin: .5rem 0 0;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: clamp(2.1rem, 6.6vw, 4.4rem);
  line-height: 1.04;
  color: var(--clay-deep);
  max-width: 22ch;
}

.page-about .about-hero__lead {
  margin: clamp(14px, 2vw, 22px) 0 0;
  max-width: 62ch;
  color: var(--ink-soft);
  font-size: clamp(1rem, 1.6vw, 1.08rem);
}

.page-about .about-facts {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin-top: clamp(24px, 3.6vw, 44px);
  background: var(--line-soft);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-fact {
  background: var(--paper);
  padding: clamp(16px, 2.4vw, 28px);
  display: flex;
  flex-direction: column;
  gap: .3rem;
}

.page-about .about-fact__num {
  margin: 0;
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: clamp(2.2rem, 6.6vw, 3.4rem);
  line-height: 1;
  letter-spacing: .02em;
  color: var(--clay);
}

.page-about .about-fact--hours .about-fact__num { color: var(--gold); }
.page-about .about-fact--partners .about-fact__num { color: var(--peacock); }

.page-about .about-fact__label {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: clamp(.95rem, 1.6vw, 1.06rem);
  color: var(--ink);
}

.page-about .about-fact__note {
  margin: 0;
  font-size: .9rem;
  line-height: 1.75;
  color: var(--ink-mute);
}

/* ---------- 研究板骨架 ---------- */
.page-about .about-board {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--about-gap);
  padding-bottom: clamp(40px, 6vw, 80px);
}

.page-about .about-rail {
  border-top: 2px solid var(--clay);
  padding-top: 14px;
}

.page-about .about-rail__title {
  margin: 0 0 .7rem;
  font-size: .78rem;
  letter-spacing: .18em;
  color: var(--ink-mute);
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 6px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scroll-snap-type: x proximity;
  -webkit-overflow-scrolling: touch;
}

.page-about .about-rail__link {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  white-space: nowrap;
  padding: 8px 12px;
  border: 1px solid var(--line-soft);
  background: var(--paper);
  color: var(--ink-soft);
  text-decoration: none;
  font-size: .88rem;
  scroll-snap-align: start;
  transition: color var(--fast) var(--ease), border-color var(--fast) var(--ease), background var(--fast) var(--ease);
}

.page-about .about-rail__link::before {
  content: "";
  flex: 0 0 auto;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--line);
  transition: background var(--fast) var(--ease);
}

.page-about .about-rail__no {
  font-size: .78rem;
  color: var(--clay);
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--peacock-deep);
  border-color: var(--peacock);
}

.page-about .about-rail__link:hover::before,
.page-about .about-rail__link:focus-visible::before {
  background: var(--gold);
}

.page-about .about-stream {
  display: flex;
  flex-direction: column;
  gap: var(--about-block-gap);
  min-width: 0;
}

.page-about .about-block {
  border-top: 1px solid var(--line);
  padding-top: clamp(20px, 2.6vw, 32px);
  min-width: 0;
}

.page-about .about-block__head {
  display: grid;
  gap: .55rem;
  margin-bottom: clamp(18px, 2.6vw, 30px);
}

.page-about .about-block__no {
  margin: 0;
  width: max-content;
  padding: 3px 10px;
  background: var(--clay);
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .16em;
  line-height: 1.4;
}

.page-about .about-block__head h2 {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 800;
  color: var(--clay-deep);
}

.page-about .about-block__sum {
  margin: 0;
  max-width: 62ch;
  color: var(--ink-soft);
  font-size: 1rem;
}

/* ---------- 图片 ---------- */
.page-about .media {
  position: relative;
  margin: 0;
}

.page-about .media img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--line-soft);
  background: var(--paper);
}

.page-about .media__caption {
  margin-top: .6rem;
  font-size: .84rem;
  line-height: 1.7;
  color: var(--ink-mute);
}

.page-about .about-block__media {
  margin-bottom: clamp(18px, 2.6vw, 30px);
}

/* ---------- 三级培训路径 ---------- */
.page-about .about-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: clamp(14px, 2vw, 20px);
}

.page-about .about-step {
  background: var(--paper);
  border: 1px solid var(--line-soft);
  border-left: 4px solid var(--clay);
  padding: clamp(14px, 2vw, 24px);
  transition: transform var(--fast) var(--ease), border-left-color var(--fast) var(--ease);
}

.page-about .about-step--l1 { border-left-color: var(--clay-light); }
.page-about .about-step--l2 { border-left-color: var(--peacock); }
.page-about .about-step--l3 { border-left-color: var(--clay); }

.page-about .about-step:hover,
.page-about .about-step:focus-within {
  transform: translateX(4px);
}

.page-about .about-step__top {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
}

.page-about .about-step__no {
  margin: 0;
  font-family: var(--font-mono);
  font-size: .82rem;
  letter-spacing: .16em;
  color: var(--ink-mute);
}

.page-about .about-step__hours {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--clay-deep);
}

.page-about .about-step__title {
  margin: .35rem 0 .7rem;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: clamp(1.3rem, 3.4vw, 1.7rem);
  color: var(--ink);
}

.page-about .about-step__bar {
  height: 10px;
  background: rgba(143, 166, 162, .22);
  overflow: hidden;
}

.page-about .about-step__bar::after {
  content: "";
  display: block;
  height: 100%;
  width: 33.3%;
  background: var(--clay-light);
  transition: width var(--fast) var(--ease);
}

.page-about .about-step--l2 .about-step__bar::after {
  width: 66.7%;
  background: var(--peacock);
}

.page-about .about-step--l3 .about-step__bar::after {
  width: 100%;
  background: var(--clay);
}

.page-about .about-step__meta {
  margin: .9rem 0 0;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: .35rem .9rem;
  font-size: .92rem;
}

.page-about .about-step__meta dt {
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .08em;
  color: var(--peacock-deep);
  padding-top: .25rem;
}

.page-about .about-step__meta dd {
  margin: 0;
  color: var(--ink-soft);
}

/* ---------- 团队构成 ---------- */
.page-about .about-team {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(18px, 2.6vw, 32px);
  min-width: 0;
}

.page-about .about-bars {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: clamp(14px, 1.8vw, 22px);
}

.page-about .about-bar__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
}

.page-about .about-bar__name {
  font-family: var(--font-head);
  font-weight: 800;
  font-size: 1rem;
  color: var(--ink);
}

.page-about .about-bar__num {
  font-size: .95rem;
  color: var(--ink-mute);
}

.page-about .about-bar__track {
  height: 14px;
  margin-top: 8px;
  background: rgba(143, 166, 162, .22);
  overflow: hidden;
}

.page-about .about-bar__fill {
  display: block;
  height: 100%;
  width: 0;
  transition: width 480ms var(--ease);
}

.page-about .about-bar--teachers .about-bar__fill { width: 77.8%; background: var(--clay); }
.page-about .about-bar--specs .about-bar__fill { width: 100%; background: var(--peacock); }
.page-about .about-bar--channel .about-bar__fill { width: 66.7%; background: var(--gold); }
.page-about .about-bar--service .about-bar__fill { width: 44.4%; background: var(--peacock-deep); }

.page-about .about-bar__desc {
  margin: .5rem 0 0;
  font-size: .9rem;
  line-height: 1.75;
  color: var(--ink-mute);
}

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

/* ---------- 区域节点 ---------- */
.page-about .about-region__media {
  margin-bottom: clamp(18px, 2.6vw, 28px);
}

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

.page-about .about-node {
  position: relative;
  background: var(--paper);
  padding: clamp(14px, 2vw, 20px);
  padding-left: calc(clamp(14px, 2vw, 20px) + 16px);
  transition: background var(--fast) var(--ease);
}

.page-about .about-node::before {
  content: "";
  position: absolute;
  left: clamp(14px, 2vw, 20px);
  top: calc(clamp(14px, 2vw, 20px) + .62rem);
  width: 7px;
  height: 7px;
  background: var(--clay-light);
}

.page-about .about-node--main {
  background: var(--peacock-deep);
}

.page-about .about-node--main::before {
  background: var(--gold);
}

.page-about .about-node__name {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: 1.06rem;
  color: var(--ink);
}

.page-about .about-node--main .about-node__name {
  color: var(--paper);
  font-size: clamp(1.2rem, 3vw, 1.5rem);
}

.page-about .about-node__role {
  margin: .15rem 0 .45rem;
  font-size: .76rem;
  letter-spacing: .1em;
  color: var(--peacock);
}

.page-about .about-node--main .about-node__role {
  color: var(--gold);
}

.page-about .about-node__act {
  margin: 0;
  font-size: .9rem;
  line-height: 1.75;
  color: var(--ink-mute);
}

.page-about .about-node--main .about-node__act {
  color: rgba(251, 247, 241, .82);
  max-width: 62ch;
}

/* ---------- 资质 ---------- */
.page-about .about-certs {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(14px, 2vw, 22px);
}

.page-about .about-cert {
  background: var(--paper);
  border: 1px solid var(--peacock);
  padding: clamp(16px, 2.2vw, 26px);
}

.page-about .about-cert__code {
  margin: 0 0 .4rem;
  font-family: var(--font-mono);
  font-size: .82rem;
  letter-spacing: .14em;
  color: var(--peacock-deep);
  padding-bottom: .4rem;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .about-cert__title {
  margin: .5rem 0 .4rem;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: 1.15rem;
  color: var(--ink);
}

.page-about .about-cert__desc {
  margin: 0;
  font-size: .93rem;
  line-height: 1.8;
  color: var(--ink-soft);
}

/* ---------- 编号方法 ---------- */
.page-about .about-code {
  background: var(--paper);
  border: 1px solid var(--peacock);
  padding: clamp(16px, 2.4vw, 30px);
}

.page-about .about-code__sample {
  margin: 0 0 1rem;
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: clamp(1.4rem, 4.4vw, 2.2rem);
  letter-spacing: .02em;
  color: var(--peacock-deep);
  word-break: break-all;
}

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

.page-about .about-code__parts li {
  display: grid;
  grid-template-columns: minmax(4.5rem, auto) 1fr;
  gap: .9rem;
  align-items: baseline;
  padding: .7rem 0;
  border-top: 1px solid var(--line-soft);
  font-size: .94rem;
  color: var(--ink-soft);
}

.page-about .about-code__parts .mono {
  color: var(--clay);
  font-weight: 600;
}

.page-about .about-method {
  margin: clamp(16px, 2.2vw, 24px) 0 0;
  max-width: 64ch;
  font-size: .95rem;
  color: var(--ink-soft);
}

.page-about .about-method a,
.page-about .about-scope-tail a {
  color: var(--peacock-deep);
  text-decoration: underline;
  text-decoration-color: var(--peacock);
  text-underline-offset: 3px;
}

.page-about .about-method a:hover,
.page-about .about-scope-tail a:hover {
  color: var(--clay);
}

/* ---------- 边界 ---------- */
.page-about .about-limits {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}

.page-about .about-limits li {
  background: var(--sand);
  padding: clamp(13px, 2vw, 20px) clamp(14px, 2.2vw, 24px);
  display: flex;
  gap: .7rem;
  font-size: .94rem;
  line-height: 1.8;
  color: var(--ink-soft);
}

.page-about .about-limits li::before {
  content: "—";
  flex: 0 0 auto;
  color: var(--clay);
}

.page-about .about-scope-tail {
  margin: clamp(16px, 2.2vw, 24px) 0 0;
  font-size: .95rem;
  color: var(--ink-soft);
}

/* ---------- 继续核对 ---------- */
.page-about .section.about-next {
  background: var(--clay-deep);
  color: var(--paper);
  margin-top: clamp(20px, 3vw, 40px);
  padding-top: clamp(30px, 4.4vw, 56px);
  padding-bottom: clamp(30px, 4.4vw, 56px);
  border-top: 3px solid var(--gold);
}

.page-about .about-next__title {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 800;
  color: var(--paper);
}

.page-about .about-next__lead {
  margin: .5rem 0 clamp(18px, 2.6vw, 28px);
  max-width: 52ch;
  font-size: .95rem;
  color: rgba(251, 247, 241, .78);
}

.page-about .about-next__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: rgba(251, 247, 241, .22);
  border-top: 1px solid rgba(251, 247, 241, .22);
  border-bottom: 1px solid rgba(251, 247, 241, .22);
}

.page-about .about-next__link {
  display: flex;
  align-items: baseline;
  gap: .85rem;
  padding: clamp(13px, 1.8vw, 18px) 0;
  color: var(--paper);
  text-decoration: none;
  font-size: .98rem;
  transition: color var(--fast) var(--ease), padding-left var(--fast) var(--ease);
}

.page-about .about-next__link .mono {
  font-size: .78rem;
  color: var(--gold);
}

.page-about .about-next__link:hover,
.page-about .about-next__link:focus-visible {
  color: var(--gold);
  padding-left: 6px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .about-facts {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

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

  .page-about .about-node--main {
    grid-column: 1 / -1;
  }

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

@media (min-width: 900px) {
  .page-about .about-board {
    grid-template-columns: minmax(180px, 236px) minmax(0, 1fr);
    gap: clamp(32px, 4vw, 72px);
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--sticky-top) + 18px);
    padding-top: 12px;
  }

  .page-about .about-rail__list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .about-rail__link {
    width: 100%;
    border: 0;
    border-bottom: 1px solid var(--line-soft);
    background: transparent;
    padding: 11px 0;
    font-size: .92rem;
  }

  .page-about .about-rail__link:hover,
  .page-about .about-rail__link:focus-visible {
    border-bottom-color: var(--peacock);
  }

  .page-about .about-team {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, .85fr);
    align-items: start;
  }

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

  .page-about .about-node--main {
    grid-column: 1 / -1;
  }

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

@media (min-width: 1180px) {
  .page-about .about-steps {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: clamp(18px, 2vw, 26px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-bar__fill,
  .page-about .about-step,
  .page-about .about-next__link {
    transition: none;
  }

  .page-about .about-step:hover,
  .page-about .about-step:focus-within {
    transform: none;
  }

  .page-about .about-next__link:hover,
  .page-about .about-next__link:focus-visible {
    padding-left: 0;
  }
}