.page-about {
  --about-rail-w: 208px;
  --about-rail-top: 104px;
  --about-edge: clamp(0.9rem, 2.2vw, 1.4rem);
  padding-bottom: clamp(2.5rem, 7vw, 5rem);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding: clamp(1rem, 3vw, 1.6rem) 0 clamp(2.2rem, 5.5vw, 3.6rem);
  background:
    radial-gradient(120% 92% at 86% -10%, rgba(255, 90, 31, 0.2), transparent 62%),
    linear-gradient(180deg, rgba(42, 45, 49, 0.92), rgba(30, 32, 35, 0));
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  right: -12%;
  top: 4%;
  width: 52%;
  height: 130%;
  background: linear-gradient(158deg, rgba(255, 90, 31, 0.18), rgba(0, 229, 255, 0.07));
  clip-path: polygon(30% 0, 100% 0, 70% 100%, 0 100%);
  pointer-events: none;
}

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

.page-about .about-hero .eyebrow {
  margin-top: clamp(1rem, 3vw, 1.8rem);
}

.page-about .about-hero h1 {
  margin: 0.5rem 0 0;
  font-family: var(--font-display);
  font-size: clamp(2.15rem, 7.6vw, 4.6rem);
  line-height: 0.96;
  letter-spacing: -0.02em;
  max-width: 15ch;
}

.page-about .about-lede {
  margin: clamp(1rem, 2.6vw, 1.5rem) 0 0;
  max-width: 56ch;
  font-size: clamp(0.98rem, 1.6vw, 1.12rem);
  line-height: 1.85;
  color: var(--c-dust);
}

.page-about .hero-stats {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: clamp(1.5rem, 4vw, 2.4rem) 0 0;
  padding: 0;
  background: var(--c-steel);
  border-bottom: 2px solid var(--c-orange);
}

.page-about .hero-stat {
  background: var(--c-graphite);
  padding: 0.85rem 0.9rem;
  display: grid;
  gap: 0.15rem;
}

.page-about .hero-stat b {
  font-family: var(--font-display);
  font-size: clamp(1.7rem, 5vw, 2.5rem);
  line-height: 1;
  letter-spacing: -0.01em;
  color: var(--c-cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .hero-stat span {
  font-size: 0.8rem;
  color: var(--c-dust);
  letter-spacing: 0.02em;
}

/* ---------- 分屏骨架 ---------- */
.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(1.2rem, 3vw, 2.4rem);
  padding-top: clamp(1.6rem, 4vw, 3rem);
}

/* ---------- 左侧纵向时间轴 ---------- */
.page-about .about-rail {
  min-width: 0;
}

.page-about .rail-sticky {
  position: static;
}

.page-about .rail-title {
  margin: 0 0 0.5rem;
  font-size: 0.75rem;
  letter-spacing: 0.18em;
  color: var(--c-dust);
  text-transform: uppercase;
}

.page-about .rail-list {
  list-style: none;
  display: flex;
  gap: 0.5rem;
  margin: 0;
  padding: 0 0 0.7rem;
  overflow-x: auto;
  border-bottom: 1px solid var(--c-steel);
  scrollbar-width: thin;
}

.page-about .rail-list::before {
  content: none;
}

.page-about .rail-item {
  flex: 0 0 auto;
}

.page-about .rail-node {
  position: relative;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 0.7rem;
  border: 1px solid var(--c-steel);
  background: var(--c-graphite);
  color: var(--c-dust);
  font-size: 0.82rem;
  line-height: 1.2;
  text-decoration: none;
  white-space: nowrap;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease), background 0.2s var(--ease);
}

.page-about .rail-node:hover,
.page-about .rail-node:focus-visible {
  color: var(--c-bone);
  border-color: var(--c-orange);
}

.page-about .rail-node.is-current {
  color: var(--c-concrete);
  background: var(--c-orange);
  border-color: var(--c-orange);
}

.page-about .node-dot {
  display: none;
}

.page-about .node-label {
  display: block;
}

.page-about .node-meta {
  display: none;
  font-size: 0.7rem;
  color: var(--c-steel);
  font-variant-numeric: tabular-nums;
}

.page-about .rail-node.is-current .node-meta {
  color: var(--c-orange-deep);
}

/* ---------- 章节通用 ---------- */
.page-about .about-section {
  padding-block: clamp(1.6rem, 4vw, 2.8rem);
  border-top: 1px solid var(--c-steel);
}

.page-about .about-section:first-child {
  padding-top: 0;
  border-top: 0;
}

.page-about .sec-index {
  margin: 0 0 0.35rem;
  font-family: var(--font-display);
  font-size: clamp(2.2rem, 6vw, 3.4rem);
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1.4px var(--c-steel);
  letter-spacing: 0.02em;
}

.page-about .about-section h2 {
  margin: 0 0 1rem;
  font-family: var(--font-display);
  font-size: clamp(1.55rem, 4.4vw, 2.5rem);
  line-height: 1.14;
  letter-spacing: -0.01em;
  color: var(--c-bone);
}

.page-about .about-section > p {
  margin: 0 0 1rem;
  max-width: 62ch;
  font-size: clamp(0.94rem, 1.5vw, 1rem);
  line-height: 1.85;
  color: var(--c-bone);
}

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

.page-about .img-frame {
  margin: clamp(1.3rem, 3.4vw, 2.1rem) 0 0;
}

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

.page-about .img-frame-caption {
  margin: 0.6rem 0 1.2rem;
  padding-left: 0.75rem;
  border-left: 2px solid var(--c-orange);
  font-size: 0.82rem;
  line-height: 1.7;
  color: var(--c-dust);
  max-width: 52ch;
}

/* ---------- 斜切引文块 ---------- */
.page-about .pull-quote {
  position: relative;
  margin: clamp(1.5rem, 4vw, 2.4rem) 0 0;
  padding: clamp(1.15rem, 3vw, 1.9rem) clamp(1.15rem, 3.6vw, 2.3rem);
  background: var(--c-bone);
  color: var(--c-concrete);
  clip-path: polygon(0 18px, 100% 0, 100% calc(100% - 18px), 0 100%);
  border-left: 4px solid var(--c-orange);
}

.page-about .pull-quote p {
  margin: 0 0 0.7rem;
  max-width: 42ch;
  font-size: clamp(1rem, 2.2vw, 1.3rem);
  font-weight: 700;
  line-height: 1.55;
  color: var(--c-concrete);
}

.page-about .quote-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.83rem;
  font-weight: 700;
  color: var(--c-orange-deep);
  text-decoration: none;
  border-bottom: 1px solid rgba(196, 61, 11, 0.45);
  padding-bottom: 1px;
  transition: opacity 0.2s var(--ease), transform 0.2s var(--ease);
}

.page-about .pull-quote:hover .quote-link,
.page-about .quote-link:focus-visible {
  transform: translateX(4px);
  border-bottom-color: var(--c-orange-deep);
  outline: none;
}

.page-about .quote-link:focus-visible {
  outline: 2px solid var(--c-cyan-deep);
  outline-offset: 3px;
}

/* ---------- 核对步骤 ---------- */
.page-about .check-steps {
  list-style: none;
  display: grid;
  gap: 1px;
  margin: clamp(1.2rem, 3vw, 1.9rem) 0 0;
  padding: 0;
  background: var(--c-steel);
  border-left: 3px solid var(--c-orange);
}

.page-about .check-steps li {
  background: var(--c-graphite);
  padding: 0.85rem 1rem;
  display: grid;
  gap: 0.25rem;
}

.page-about .check-steps b {
  font-size: 0.86rem;
  letter-spacing: 0.06em;
  color: var(--c-orange);
}

.page-about .check-steps span {
  font-size: 0.88rem;
  line-height: 1.75;
  color: var(--c-dust);
}

/* ---------- 版本台阶 ---------- */
.page-about .ver-list {
  display: grid;
  gap: 0.55rem;
  margin: clamp(1.2rem, 3vw, 1.9rem) 0 0;
}

.page-about .ver-item {
  background: var(--c-graphite);
  border-left: 3px solid var(--c-steel);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 12px), calc(100% - 12px) 100%, 0 100%);
  transition: border-color 0.2s var(--ease);
}

.page-about .ver-item[open] {
  border-left-color: var(--c-orange);
}

.page-about .ver-item summary {
  display: grid;
  grid-template-columns: 3.2rem minmax(0, 1fr) 1.1rem;
  align-items: center;
  gap: 0.6rem;
  padding: 0.8rem 1rem;
  cursor: pointer;
  list-style: none;
}

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

.page-about .ver-item summary:focus-visible {
  outline: 2px solid var(--c-cyan);
  outline-offset: -2px;
}

.page-about .ver-tag {
  font-family: var(--font-display);
  font-size: 1.05rem;
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--c-orange);
  font-variant-numeric: tabular-nums;
}

.page-about .ver-title {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--c-bone);
}

.page-about .ver-plus {
  font-size: 1.1rem;
  line-height: 1;
  color: var(--c-dust);
  text-align: center;
  transition: transform 0.22s var(--ease), color 0.2s var(--ease);
}

.page-about .ver-item[open] .ver-plus {
  transform: rotate(45deg);
  color: var(--c-cyan);
}

.page-about .ver-body {
  margin: 0;
  padding: 0 1rem 0.95rem;
  font-size: 0.88rem;
  line-height: 1.8;
  color: var(--c-dust);
}

.page-about .ver-stairs {
  display: block;
  width: 100%;
  height: auto;
  margin-top: clamp(1.1rem, 3vw, 1.7rem);
}

/* ---------- 团队方块图 ---------- */
.page-about .team-blocks {
  display: grid;
  gap: 1rem;
  margin: clamp(1.3rem, 3.4vw, 2rem) 0 0;
  padding: clamp(1rem, 2.6vw, 1.4rem);
  background: var(--c-graphite);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 16px), calc(100% - 16px) 100%, 0 100%);
}

.page-about .team-head {
  display: flex;
  align-items: baseline;
  gap: 0.4rem;
  margin: 0 0 0.45rem;
}

.page-about .team-num {
  font-family: var(--font-display);
  font-size: 1.9rem;
  line-height: 1;
  color: var(--c-orange);
  font-variant-numeric: tabular-nums;
}

.page-about .team-name {
  font-size: 0.82rem;
  color: var(--c-dust);
}

.page-about .team-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
}

.page-about .team-cell {
  width: 15px;
  height: 15px;
  display: block;
}

.page-about .team-cell--editing {
  background: var(--c-orange);
}

.page-about .team-cell--eng {
  background: var(--c-cyan);
}

.page-about .team-cell--design {
  background: var(--c-bone);
}

/* ---------- 合作统计 ---------- */
.page-about .partner-stats {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: clamp(1.2rem, 3vw, 1.9rem) 0 1.3rem;
  padding: 0;
  background: var(--c-steel);
  border-top: 2px solid var(--c-cyan);
}

.page-about .partner-stats li {
  background: var(--c-graphite);
  padding: 0.85rem 0.9rem;
  display: grid;
  gap: 0.2rem;
}

.page-about .partner-stats b {
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 4.4vw, 2.2rem);
  line-height: 1;
  color: var(--c-cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .partner-stats span {
  font-size: 0.8rem;
  line-height: 1.5;
  color: var(--c-dust);
}

.page-about .text-link {
  color: var(--c-cyan);
  font-size: 0.9rem;
  font-weight: 700;
  text-decoration: none;
  border-bottom: 1px solid rgba(0, 229, 255, 0.4);
  padding-bottom: 1px;
  transition: border-color 0.2s var(--ease), color 0.2s var(--ease);
}

.page-about .text-link:hover,
.page-about .text-link:focus-visible {
  color: var(--c-bone);
  border-bottom-color: var(--c-bone);
}

/* ---------- 接下来 ---------- */
.page-about .next-list {
  list-style: none;
  display: grid;
  gap: 1rem;
  margin: clamp(1.2rem, 3vw, 1.9rem) 0 1.3rem;
  padding: 0;
}

.page-about .next-list li {
  padding-left: 0.9rem;
  border-left: 2px solid var(--c-steel);
  transition: border-color 0.2s var(--ease);
}

.page-about .next-list li:hover {
  border-left-color: var(--c-orange);
}

.page-about .next-list b {
  display: block;
  margin-bottom: 0.3rem;
  font-size: 0.95rem;
  color: var(--c-bone);
}

.page-about .next-list span {
  display: block;
  font-size: 0.87rem;
  line-height: 1.78;
  color: var(--c-dust);
}

.page-about .about-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  margin-top: clamp(1.3rem, 3.4vw, 2rem);
}

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

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

  .page-about .team-blocks {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.2rem;
  }

  .page-about .team-bar {
    max-width: 100%;
  }
}

/* ---------- 桌面：左轴 + 右文 ---------- */
@media (min-width: 900px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: clamp(2rem, 4.5vw, 4rem);
    align-items: start;
  }

  .page-about .rail-sticky {
    position: sticky;
    top: var(--about-rail-top);
  }

  .page-about .rail-list {
    display: block;
    overflow: visible;
    border-bottom: 0;
    padding: 0;
  }

  .page-about .rail-list::before {
    content: "";
    position: absolute;
    left: 4px;
    top: 10px;
    bottom: 10px;
    width: 2px;
    background: linear-gradient(180deg, var(--c-orange), var(--c-steel) 70%, transparent);
  }

  .page-about .rail-item {
    position: relative;
  }

  .page-about .rail-node {
    display: block;
    padding: 0.5rem 0 0.5rem 1.85rem;
    border: 0;
    background: transparent;
    white-space: normal;
  }

  .page-about .rail-node:hover,
  .page-about .rail-node:focus-visible {
    background: transparent;
  }

  .page-about .rail-node.is-current {
    background: transparent;
    color: var(--c-bone);
  }

  .page-about .node-dot {
    display: block;
    position: absolute;
    left: 0;
    top: 0.78rem;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--c-steel);
    transition: background 0.24s var(--ease), box-shadow 0.24s var(--ease), transform 0.24s var(--ease);
  }

  .page-about .rail-node:hover .node-dot {
    background: var(--c-orange-deep);
  }

  .page-about .rail-node.is-current .node-dot {
    background: var(--c-orange);
    transform: scale(1.3);
    box-shadow: 0 0 0 5px rgba(255, 90, 31, 0.18);
  }

  .page-about .node-label {
    font-size: 0.88rem;
    font-weight: 700;
  }

  .page-about .node-meta {
    display: block;
    margin-top: 0.1rem;
    font-size: 0.72rem;
    color: var(--c-steel);
  }

  .page-about .check-steps {
    border-left-width: 3px;
  }

  .page-about .about-section > p,
  .page-about .pull-quote p {
    max-width: 60ch;
  }
}

@media (min-width: 1120px) {
  .page-about {
    --about-rail-w: 232px;
  }

  .page-about .about-hero h1 {
    max-width: 17ch;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .rail-node,
  .page-about .node-dot,
  .page-about .quote-link,
  .page-about .ver-plus,
  .page-about .text-link,
  .page-about .next-list li {
    transition: none;
  }
}