.page-about {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  background-color: var(--night);
  background-image:
    radial-gradient(1100px 560px at 78% -12%, rgba(31, 166, 166, .30), transparent 62%),
    radial-gradient(900px 520px at 6% 112%, rgba(18, 48, 90, .95), transparent 72%),
    linear-gradient(180deg, var(--night) 0%, var(--night-2) 100%);
  color: var(--data-bg);
  padding: calc(var(--head-h) + clamp(26px, 6vw, 68px)) 0 clamp(46px, 7vw, 92px);
  overflow: hidden;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(126, 217, 217, .07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(126, 217, 217, .07) 1px, transparent 1px);
  background-size: 76px 76px;
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, .85), transparent 88%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, .85), transparent 88%);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    radial-gradient(1.5px 1.5px at 14% 28%, rgba(232, 237, 243, .55), transparent 70%),
    radial-gradient(1.5px 1.5px at 41% 12%, rgba(232, 237, 243, .40), transparent 70%),
    radial-gradient(1.5px 1.5px at 70% 43%, rgba(232, 237, 243, .50), transparent 70%),
    radial-gradient(1.5px 1.5px at 88% 19%, rgba(232, 237, 243, .34), transparent 70%),
    radial-gradient(1.5px 1.5px at 26% 70%, rgba(232, 237, 243, .30), transparent 70%),
    radial-gradient(1.5px 1.5px at 61% 82%, rgba(232, 237, 243, .34), transparent 70%);
}

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

.page-about .about-hero-grid {
  display: grid;
  gap: clamp(26px, 4vw, 46px);
  margin-top: clamp(22px, 4vw, 48px);
}

.page-about .about-hero-grid > * {
  min-width: 0;
}

.page-about .about-hero .display {
  font-size: clamp(1.95rem, 6.2vw, 4.3rem);
  line-height: 1.07;
  letter-spacing: -.02em;
  font-weight: 800;
  color: #ffffff;
  margin: .42em 0 .62em;
  max-width: 18ch;
}

.page-about .about-hero .lede {
  max-width: 48ch;
  font-size: clamp(1rem, 1.5vw, 1.1rem);
  line-height: 1.8;
  color: rgba(232, 237, 243, .78);
  margin: 0;
}

.page-about .about-hero-panel {
  position: relative;
  background: rgba(18, 48, 90, .74);
  border: 1px solid rgba(242, 140, 40, .55);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lift);
  padding: clamp(18px, 2.6vw, 26px);
}

.page-about .about-hero-panel-title {
  margin: 0;
  font-size: .8125rem;
  letter-spacing: .16em;
  color: var(--teal-soft);
}

.page-about .about-facts {
  list-style: none;
  margin: 16px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .about-facts li {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line-dark);
}

.page-about .about-facts li:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

.page-about .about-fact-num {
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--flame);
  min-width: 3.8em;
  letter-spacing: -.01em;
}

.page-about .about-fact-label {
  font-size: .9375rem;
  color: var(--on-dark);
  line-height: 1.5;
}

.page-about .about-fact-note {
  margin: 16px 0 0;
  font-size: .75rem;
  line-height: 1.6;
  color: rgba(232, 237, 243, .58);
}

/* ---------- 章节导航条 ---------- */
.page-about .about-rail {
  position: sticky;
  top: var(--head-h);
  z-index: 20;
  background: rgba(244, 241, 234, .94);
  border-bottom: 1px solid var(--line-light);
  -webkit-backdrop-filter: blur(6px);
  backdrop-filter: blur(6px);
}

.page-about .about-rail-inner {
  display: flex;
  gap: 2px;
  overflow-x: auto;
  scrollbar-width: none;
}

.page-about .about-rail-inner::-webkit-scrollbar {
  display: none;
}

.page-about .about-rail-link {
  flex: 0 0 auto;
  padding: 15px 12px 13px;
  font-size: .875rem;
  line-height: 1.2;
  color: var(--muted);
  text-decoration: none;
  white-space: nowrap;
  border-bottom: 2px solid transparent;
  transition: color 160ms ease, border-color 160ms ease;
}

.page-about .about-rail-link:hover,
.page-about .about-rail-link:focus-visible {
  color: var(--ink);
  border-bottom-color: var(--teal-soft);
}

.page-about .about-rail-link[aria-current="true"] {
  color: var(--ink);
  font-weight: 600;
  border-bottom-color: var(--teal);
}

/* ---------- 通用区块 ---------- */
.page-about .about-block {
  padding: clamp(48px, 8vw, 104px) 0;
  scroll-margin-top: calc(var(--head-h) + 56px);
}

.page-about .about-block--dark {
  background: var(--night);
  color: var(--data-bg);
  position: relative;
}

.page-about .about-block--data {
  background: var(--data-bg);
}

.page-about .about-block-head {
  max-width: 62ch;
}

.page-about .about-block-head .section-title {
  margin: .34em 0 .5em;
  font-size: clamp(1.6rem, 3.6vw, 2.5rem);
  line-height: 1.2;
  letter-spacing: -.015em;
  font-weight: 800;
  color: var(--ink);
}

.page-about .about-block--dark .about-block-head .section-title {
  color: #ffffff;
}

.page-about .about-lede {
  margin: 0;
  font-size: 1rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .about-block--dark .about-lede {
  color: var(--on-dark);
}

.page-about .about-inline-note {
  margin: clamp(22px, 3vw, 34px) 0 0;
  font-size: .78rem;
  line-height: 1.65;
  color: var(--muted);
  max-width: 62ch;
}

.page-about .about-block--dark .about-inline-note {
  color: rgba(232, 237, 243, .55);
}

/* ---------- 起点：双栏 ---------- */
.page-about .about-two-col {
  display: grid;
  gap: clamp(24px, 4vw, 52px);
  margin-top: clamp(22px, 3.5vw, 40px);
}

.page-about .about-prose p {
  margin: 0 0 1.15em;
  font-size: 1rem;
  line-height: 1.82;
  color: var(--ink);
}

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

.page-about .about-side-note {
  border-top: 2px solid var(--teal);
  padding-top: 18px;
}

.page-about .about-side-title {
  margin: 0 0 14px;
  font-size: .8125rem;
  letter-spacing: .14em;
  color: var(--muted);
}

.page-about .about-side-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .about-side-list li {
  position: relative;
  padding-left: 18px;
  font-size: .9375rem;
  line-height: 1.7;
  color: var(--ink);
}

.page-about .about-side-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .78em;
  width: 9px;
  height: 1px;
  background: var(--flame);
}

/* ---------- 赛季时间轴 ---------- */
.page-about .about-season-figure {
  margin: clamp(26px, 4vw, 44px) 0 clamp(30px, 4.5vw, 52px);
}

.page-about .about-timeline {
  position: relative;
  margin: 0 0 0 6px;
  padding-left: 0;
  border-left: 1px solid var(--line-dark);
}

.page-about .about-season {
  position: relative;
  padding: 0 0 30px 26px;
  border-bottom: 1px solid var(--line-dark);
}

.page-about .about-season:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

.page-about .about-season::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 27px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--flame);
  box-shadow: 0 0 0 4px rgba(242, 140, 40, .18);
}

.page-about .about-season-trigger {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px 14px;
  width: 100%;
  margin: 0;
  padding: 16px 0 8px;
  background: none;
  border: 0;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  -webkit-appearance: none;
  appearance: none;
}

.page-about .about-season-year {
  font-family: var(--font-mono);
  font-size: clamp(1.35rem, 3.2vw, 2rem);
  font-weight: 700;
  color: var(--flame);
  letter-spacing: -.015em;
  line-height: 1;
}

.page-about .about-season-tag {
  font-size: .6875rem;
  letter-spacing: .14em;
  padding: 3px 9px;
  border: 1px solid var(--line-dark);
  border-radius: 999px;
  color: var(--on-dark);
  white-space: nowrap;
}

.page-about .about-season-headline {
  flex: 1 1 240px;
  min-width: 0;
  font-size: clamp(.98rem, 1.5vw, 1.1rem);
  font-weight: 600;
  line-height: 1.55;
  color: #ffffff;
}

.page-about .about-season .timeline-caret {
  flex: 0 0 auto;
  width: 9px;
  height: 9px;
  border-right: 1.5px solid var(--teal);
  border-bottom: 1.5px solid var(--teal);
  transform: rotate(45deg) translate(-2px, -2px);
  transition: transform 240ms ease;
  align-self: center;
}

.page-about .about-season[data-open] .timeline-caret {
  transform: rotate(-135deg) translate(-2px, -2px);
}

.page-about .about-season-body {
  overflow: hidden;
}

.page-about .about-season:not([data-open]) .about-season-body {
  display: none;
}

.page-about .about-season-list {
  list-style: none;
  margin: 10px 0 0;
  padding: 0;
  display: grid;
  gap: 9px;
  max-width: 68ch;
}

.page-about .about-season-list li {
  position: relative;
  padding-left: 18px;
  font-size: .9375rem;
  line-height: 1.72;
  color: var(--on-dark);
}

.page-about .about-season-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .76em;
  width: 9px;
  height: 1px;
  background: var(--teal);
}

/* ---------- 团队分工 ---------- */
.page-about .about-team-bar {
  display: flex;
  gap: 3px;
  margin: clamp(24px, 3.5vw, 42px) 0 0;
}

.page-about .team-seg {
  position: relative;
  min-width: 0;
  min-height: 112px;
  padding: 15px 13px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 8px;
  border-radius: var(--radius);
  color: var(--ink);
  transition: transform 200ms ease, box-shadow 200ms ease;
}

.page-about .team-seg:hover,
.page-about .team-seg:focus-within {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
  z-index: 4;
}

.page-about .team-seg--ops {
  flex: 16 1 0;
  background: rgba(31, 166, 166, .17);
  border: 1px solid rgba(31, 166, 166, .42);
}

.page-about .team-seg--data {
  flex: 9 1 0;
  background: rgba(126, 217, 217, .22);
  border: 1px solid rgba(126, 217, 217, .55);
}

.page-about .team-seg--fe {
  flex: 6 1 0;
  background: rgba(242, 140, 40, .16);
  border: 1px solid rgba(242, 140, 40, .42);
}

.page-about .team-seg--qa {
  flex: 3 1 0;
  background: rgba(107, 124, 147, .14);
  border: 1px solid var(--line-light);
}

.page-about .team-seg-count {
  font-family: var(--font-mono);
  font-size: clamp(1.35rem, 2.4vw, 1.75rem);
  font-weight: 700;
  line-height: 1;
  color: var(--night);
}

.page-about .team-seg-name {
  font-size: .875rem;
  font-weight: 600;
  line-height: 1.4;
  letter-spacing: .01em;
  color: var(--ink);
  word-break: break-word;
}

.page-about .team-seg-tip {
  position: absolute;
  left: 0;
  bottom: calc(100% + 8px);
  width: min(258px, 72vw);
  padding: 10px 12px;
  background: var(--night);
  color: var(--data-bg);
  border: 1px solid rgba(31, 166, 166, .5);
  border-radius: var(--radius);
  font-size: .8125rem;
  line-height: 1.6;
  opacity: 0;
  visibility: hidden;
  transform: translateY(5px);
  transition: opacity 160ms ease, transform 160ms ease, visibility 160ms;
  pointer-events: none;
  z-index: 6;
}

.page-about .team-seg:hover .team-seg-tip,
.page-about .team-seg:focus-within .team-seg-tip {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.page-about .about-team-flow {
  margin-top: clamp(30px, 4.5vw, 52px);
}

.page-about .about-sub-title {
  margin: 0 0 18px;
  font-size: clamp(1.05rem, 1.9vw, 1.3rem);
  font-weight: 700;
  line-height: 1.5;
  color: var(--ink);
}

.page-about .about-step-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line-light);
}

.page-about .about-step {
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr);
  gap: 12px;
  align-items: start;
  padding: 16px 0;
  border-bottom: 1px solid var(--line-light);
}

.page-about .about-step-no {
  font-family: var(--font-mono);
  font-size: .875rem;
  font-weight: 700;
  color: var(--teal);
  letter-spacing: .04em;
  line-height: 1.7;
}

.page-about .about-step-text {
  margin: 0;
  font-size: .9375rem;
  line-height: 1.72;
  color: var(--ink);
  max-width: 66ch;
}

/* ---------- 术语与检查 ---------- */
.page-about .about-flow-figure {
  margin: clamp(26px, 4vw, 44px) 0 clamp(28px, 4vw, 46px);
}

.page-about .about-checks {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid rgba(15, 23, 32, .16);
}

.page-about .about-check {
  display: grid;
  gap: 8px;
  padding: 20px 0;
  border-bottom: 1px solid rgba(15, 23, 32, .16);
}

.page-about .about-check-no {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 700;
  color: var(--teal);
  letter-spacing: .05em;
  line-height: 1.6;
}

.page-about .about-check-title {
  margin: 0;
  font-size: clamp(1rem, 1.6vw, 1.12rem);
  font-weight: 700;
  line-height: 1.5;
  color: var(--ink);
}

.page-about .about-check p {
  margin: 0;
  font-size: .9375rem;
  line-height: 1.78;
  color: var(--ink);
  max-width: 66ch;
}

/* ---------- 西宁节点 ---------- */
.page-about .about-screens {
  display: grid;
  gap: 0;
  margin-top: clamp(26px, 4vw, 46px);
  border-top: 1px solid var(--line-dark);
}

.page-about .about-screen {
  padding: 20px 0;
  border-bottom: 1px solid var(--line-dark);
}

.page-about .about-screen-name {
  margin: 0 0 6px;
  font-size: 1.05rem;
  font-weight: 700;
  color: #ffffff;
  letter-spacing: .01em;
}

.page-about .about-screen-range {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--teal-soft);
  letter-spacing: .01em;
}

.page-about .about-screen-density {
  margin: 0 0 8px;
  font-size: .9375rem;
  color: var(--flame);
}

.page-about .about-screen-density .num {
  font-family: var(--font-mono);
  font-size: 1.15rem;
  font-weight: 700;
}

.page-about .about-screen-focus {
  margin: 0;
  font-size: .875rem;
  line-height: 1.7;
  color: var(--on-dark);
}

.page-about .about-xining-notes {
  margin-top: clamp(26px, 4vw, 44px);
  max-width: 68ch;
}

.page-about .about-xining-notes p {
  margin: 0 0 1em;
  font-size: .9375rem;
  line-height: 1.8;
  color: var(--on-dark);
}

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

.page-about .about-xining-notes .about-inline-note {
  color: rgba(232, 237, 243, .55);
}

/* ---------- 交付能力 ---------- */
.page-about .about-deliver-list {
  list-style: none;
  margin: clamp(26px, 4vw, 46px) 0 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line-light);
}

.page-about .about-deliver-item {
  position: relative;
  padding: 22px 0 22px 0;
  border-bottom: 1px solid var(--line-light);
}

.page-about .about-deliver-no {
  font-family: var(--font-mono);
  font-size: .8125rem;
  font-weight: 700;
  letter-spacing: .08em;
  color: var(--teal);
  display: block;
  margin-bottom: 8px;
}

.page-about .about-deliver-title {
  margin: 0 0 8px;
  font-size: clamp(1.02rem, 1.7vw, 1.18rem);
  font-weight: 700;
  line-height: 1.5;
  color: var(--ink);
}

.page-about .about-deliver-item p {
  margin: 0 0 12px;
  font-size: .9375rem;
  line-height: 1.78;
  color: var(--ink);
  max-width: 64ch;
}

.page-about .about-deliver-item .link-arrow {
  font-size: .875rem;
}

/* ---------- 收束横幅 ---------- */
.page-about .about-horizon {
  position: relative;
  min-height: 300px;
  display: flex;
  align-items: flex-end;
  overflow: hidden;
  background: var(--night);
}

.page-about .about-horizon img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: .5;
  filter: saturate(.55);
}

.page-about .about-horizon::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(11, 31, 58, .35) 0%, rgba(11, 31, 58, .88) 72%, var(--night) 100%);
}

.page-about .about-horizon-inner {
  position: relative;
  z-index: 1;
  width: 100%;
  padding: clamp(40px, 7vw, 76px) var(--gutter);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.page-about .about-horizon-line {
  margin: 0;
  max-width: 32ch;
  font-size: clamp(1.05rem, 2.4vw, 1.6rem);
  font-weight: 700;
  line-height: 1.5;
  letter-spacing: -.01em;
  color: #ffffff;
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .about-check {
    grid-template-columns: 56px minmax(130px, 200px) minmax(0, 1fr);
    gap: 20px;
    align-items: start;
  }

  .page-about .about-check-no {
    padding-top: 2px;
  }

  .page-about .about-checks {
    border-top: 1px solid rgba(15, 23, 32, .16);
  }

  .page-about .about-step {
    grid-template-columns: 56px minmax(0, 1fr);
    gap: 18px;
    padding: 18px 0;
  }

  .page-about .about-screens {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: clamp(24px, 4vw, 48px);
    border-bottom: 1px solid var(--line-dark);
  }

  .page-about .about-screen {
    border-bottom: 0;
    border-top: 0;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero-grid {
    grid-template-columns: minmax(0, 7fr) minmax(296px, 4fr);
    align-items: end;
  }

  .page-about .about-two-col {
    grid-template-columns: minmax(0, 7fr) minmax(260px, 4fr);
    align-items: start;
  }

  .page-about .about-side-note {
    margin-top: 6px;
  }

  .page-about .about-timeline {
    margin-left: 12px;
  }

  .page-about .about-season {
    padding-left: 38px;
  }

  .page-about .about-season::before {
    left: -5px;
  }

  .page-about .about-deliver-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: clamp(28px, 4vw, 56px);
  }

  .page-about .about-deliver-item {
    padding: 24px 0;
  }
}

@media (min-width: 1100px) {
  .page-about .about-screens {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    column-gap: clamp(22px, 3vw, 40px);
  }
}

@media (max-width: 719px) {
  .page-about .about-team-bar {
    flex-direction: column;
    gap: 8px;
  }

  .page-about .team-seg {
    flex: 1 1 auto;
    min-height: 0;
    padding: 14px 15px;
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    grid-template-areas:
      "count name"
      "tip tip";
    align-items: center;
    gap: 4px 12px;
  }

  .page-about .team-seg-count {
    grid-area: count;
    font-size: 1.35rem;
  }

  .page-about .team-seg-name {
    grid-area: name;
  }

  .page-about .team-seg-tip {
    grid-area: tip;
    position: static;
    width: auto;
    opacity: 1;
    visibility: visible;
    transform: none;
    background: transparent;
    border: 0;
    border-radius: 0;
    padding: 4px 0 0;
    color: var(--muted);
    font-size: .8125rem;
  }

  .page-about .team-seg:hover,
  .page-about .team-seg:focus-within {
    transform: none;
    box-shadow: none;
  }

  .page-about .about-horizon {
    min-height: 240px;
  }

  .page-about .about-horizon-inner {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-season .timeline-caret,
  .page-about .team-seg,
  .page-about .team-seg-tip,
  .page-about .about-rail-link {
    transition: none;
  }

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