/* ===== 平台概览页 · 纵向序号轴 + 宽窄交替 ===== */
.page-about {
  background: var(--paper);
  color: var(--ink);
  overflow-x: hidden;
}

/* ---------- 面包屑 ---------- */
.page-about .breadcrumbs {
  padding: clamp(16px, 2.6vw, 26px) 0 clamp(10px, 1.6vw, 16px);
}

/* ---------- 首屏拼贴 ---------- */
.page-about .about-hero {
  background:
    radial-gradient(120% 90% at 88% 8%, rgba(53, 224, 200, 0.16) 0%, rgba(53, 224, 200, 0) 62%),
    radial-gradient(90% 70% at 6% 100%, rgba(18, 49, 79, 0.9) 0%, rgba(10, 27, 46, 0) 70%),
    var(--ink);
  color: var(--paper);
  padding: clamp(28px, 4.6vw, 56px) 0 clamp(40px, 6vw, 84px);
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
}

.page-about .about-hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3.4vw, 30px);
}

.page-about .about-hero__lead h1 {
  margin: 10px 0 0;
  font-size: clamp(2.1rem, 8.2vw, 4.4rem);
  line-height: 1.08;
  font-weight: 300;
  letter-spacing: -0.02em;
  color: var(--paper);
  max-width: 18ch;
}

.page-about .about-hero .eyebrow {
  color: var(--cyan);
}

.page-about .about-hero .lead {
  margin-top: clamp(16px, 2.2vw, 24px);
  font-size: var(--t-1);
  line-height: 1.75;
  color: var(--ice);
  max-width: 56ch;
}

.page-about .about-hero__panel {
  align-self: start;
  background: var(--ink-2);
  border: 1px solid rgba(53, 224, 200, 0.28);
  border-radius: var(--radius-lg);
  padding: clamp(20px, 3.2vw, 30px);
}

.page-about .about-hero__ptitle {
  margin: 0;
  font-size: var(--t--1);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--slate);
  color: rgba(191, 215, 232, 0.68);
}

.page-about .about-hero__ver {
  margin: 6px 0 12px;
  font-family: var(--font-mono);
  font-size: clamp(3rem, 12vw, 5.6rem);
  line-height: 0.95;
  letter-spacing: 0.02em;
  color: var(--cyan);
}

.page-about .about-hero__facts {
  list-style: none;
  margin: 18px 0 0;
  padding: 16px 0 0;
  border-top: 1px solid var(--line-inv);
  display: grid;
  gap: 10px;
  font-size: var(--t--1);
  color: var(--ice);
}

.page-about .about-hero__facts span {
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--cyan);
  letter-spacing: 0.04em;
  margin-right: 6px;
}

.page-about .about-hero__figure {
  margin: 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: var(--ink-2);
  line-height: 0;
}

.page-about .about-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 14 / 9;
  object-fit: cover;
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.55fr) minmax(0, 1fr);
    grid-template-areas:
      "lead panel"
      "fig  fig";
    align-items: start;
    column-gap: clamp(28px, 4vw, 64px);
    row-gap: clamp(28px, 4vw, 48px);
  }
  .page-about .about-hero__lead { grid-area: lead; }
  .page-about .about-hero__panel { grid-area: panel; }
  .page-about .about-hero__figure { grid-area: fig; }
  .page-about .about-hero__figure img { aspect-ratio: 14 / 6; }
}

/* ---------- 章节骨架与序号轴 ---------- */
.page-about .sec {
  padding: clamp(48px, 8vw, 104px) 0;
}

.page-about .sec--paper { background: var(--paper); }

.page-about .sec--ink {
  background: var(--ink);
  color: var(--ice);
}

.page-about .sec--ink .section__title,
.page-about .sec--ink h3 {
  color: var(--paper);
}

.page-about .sec--ink .eyebrow { color: var(--cyan); }
.page-about .sec--ink .lead { color: var(--ice); }
.page-about .sec--ink a { color: var(--cyan); }

.page-about .sec__grid {
  position: relative;
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  column-gap: clamp(12px, 2.4vw, 28px);
}

@media (min-width: 760px) {
  .page-about .sec__grid {
    grid-template-columns: 76px minmax(0, 1fr);
    column-gap: clamp(20px, 3vw, 40px);
  }
}

.page-about .sec__axis {
  position: relative;
  display: flex;
  justify-content: center;
  padding-top: 4px;
}

.page-about .sec__axis::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  width: 2px;
  transform: translateX(-1px);
  background: var(--line);
}

.page-about .sec--ink .sec__axis::before {
  background: var(--line-inv);
}

.page-about .sec__num {
  position: relative;
  z-index: 1;
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: var(--pill);
  background: var(--paper);
  border: 2px solid var(--line-strong);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
}

.page-about .sec--ink .sec__num {
  background: var(--ink);
  border-color: rgba(53, 224, 200, 0.55);
  color: var(--cyan);
}

@media (min-width: 760px) {
  .page-about .sec__num {
    width: 48px;
    height: 48px;
    font-size: 0.8125rem;
  }
}

.page-about .sec__body > * + * {
  margin-top: clamp(16px, 2.2vw, 24px);
}

.page-about .sec__body .section__title {
  font-weight: 300;
  letter-spacing: -0.02em;
  font-size: var(--t-2);
  line-height: 1.18;
  max-width: 20ch;
}

.page-about .sec__body .lead {
  max-width: 58ch;
  font-size: var(--t-1);
  line-height: 1.75;
  color: var(--slate);
}

/* ---------- 01 起点：宽窄切分 ---------- */
.page-about .split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 34px);
}

.page-about .split__main p {
  margin: 0 0 14px;
  font-size: var(--t-0);
  line-height: 1.75;
  color: var(--ink);
}

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

.page-about .split__side {
  background: var(--ripple);
  border-radius: var(--radius-lg);
  padding: clamp(18px, 3vw, 26px);
  border: 1px solid var(--line);
}

.page-about .keep-list__title {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: var(--t--1);
  letter-spacing: 0.1em;
  color: var(--ink-2);
}

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

.page-about .keep-list li {
  position: relative;
  padding-left: 22px;
  font-size: var(--t--1);
  line-height: 1.6;
  color: var(--ink);
}

.page-about .keep-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.5em;
  width: 9px;
  height: 9px;
  border-radius: var(--pill);
  background: var(--cyan);
}

@media (min-width: 900px) {
  .page-about .split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: start;
  }
}

/* ---------- 02 结构 ---------- */
.page-about .structure {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(18px, 3vw, 30px);
  align-items: center;
}

.page-about .structure__figure {
  background: rgba(18, 49, 79, 0.55);
  border: 1px solid var(--line-inv);
  border-radius: var(--radius-lg);
  padding: clamp(12px, 2.4vw, 22px);
}

.page-about .ringmap {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
}

.page-about .structure__img {
  margin: 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  line-height: 0;
  background: var(--ink-2);
}

.page-about .structure__img img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 1 / 1;
  object-fit: cover;
}

@media (min-width: 900px) {
  .page-about .structure {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  }
}

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

.page-about .layers__item {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 4px 14px;
  padding: clamp(16px, 2.4vw, 22px) 0;
  border-bottom: 1px solid var(--line-inv);
}

.page-about .layers__no {
  grid-row: span 2;
  font-family: var(--font-mono);
  font-size: 0.9375rem;
  letter-spacing: 0.04em;
  color: var(--cyan);
  padding-top: 3px;
}

.page-about .layers__title {
  margin: 0;
  font-size: var(--t-1);
  font-weight: 400;
  letter-spacing: -0.01em;
}

.page-about .layers__text {
  margin: 0;
  font-size: var(--t-0);
  line-height: 1.7;
  color: var(--ice);
}

/* ---------- 03 坐标 ---------- */
.page-about .coord {
  background: var(--ripple);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: clamp(20px, 3.4vw, 34px);
}

.page-about .coord__row {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: clamp(8px, 1.6vw, 16px);
  margin: 0 0 clamp(18px, 2.6vw, 26px);
  font-family: var(--font-mono);
  font-size: clamp(1.9rem, 7.4vw, 3.6rem);
  line-height: 1;
  letter-spacing: 0.04em;
  color: var(--ink);
}

.page-about .coord__part {
  border-bottom: 3px solid var(--cyan);
  padding-bottom: 4px;
}

.page-about .coord__sep {
  color: var(--slate);
  font-size: 0.7em;
}

.page-about .coord__legend {
  margin: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(14px, 2.2vw, 22px);
}

.page-about .coord__def dt {
  font-family: var(--font-mono);
  font-size: var(--t--1);
  letter-spacing: 0.1em;
  color: var(--ink-2);
  margin-bottom: 6px;
}

.page-about .coord__def dd {
  margin: 0;
  font-size: var(--t--1);
  line-height: 1.7;
  color: var(--ink);
}

.page-about .coord__def + .coord__def {
  padding-top: clamp(14px, 2.2vw, 22px);
  border-top: 1px solid var(--line);
}

.page-about .coord__note {
  margin: 0;
  padding-left: 16px;
  border-left: 3px solid var(--orange);
  font-size: var(--t--1);
  line-height: 1.7;
  color: var(--ink-2);
}

@media (min-width: 760px) {
  .page-about .coord__legend {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: clamp(18px, 3vw, 32px);
  }
  .page-about .coord__def + .coord__def {
    padding-top: 0;
    padding-left: clamp(18px, 3vw, 32px);
    border-top: 0;
    border-left: 1px solid var(--line);
  }
}

/* ---------- 04 时间线 ---------- */
.page-about .wave-band {
  margin: 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  line-height: 0;
  background: var(--ink-2);
}

.page-about .wave-band img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 5;
  object-fit: cover;
}

.page-about .tl {
  list-style: none;
  margin: 0;
  padding: 0 0 0 28px;
  position: relative;
}

.page-about .tl::before {
  content: "";
  position: absolute;
  left: 6px;
  top: 10px;
  bottom: 14px;
  width: 2px;
  background: var(--line-inv);
}

.page-about .tl__item {
  position: relative;
  padding-bottom: clamp(20px, 3vw, 30px);
}

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

.page-about .tl__item::before {
  content: "";
  position: absolute;
  left: -27px;
  top: 8px;
  width: 10px;
  height: 10px;
  border-radius: var(--pill);
  background: var(--amber);
  transition: background 200ms ease, transform 200ms ease;
}

.page-about .tl__item:hover::before {
  background: var(--cyan);
  transform: scale(1.25);
}

.page-about .tl__year {
  margin: 0 0 6px;
  font-family: var(--font-mono);
  font-size: 1.0625rem;
  letter-spacing: 0.06em;
  color: var(--amber);
}

.page-about .tl__title {
  margin: 0 0 6px;
  font-size: var(--t-1);
  font-weight: 400;
  letter-spacing: -0.01em;
  transition: color 200ms ease;
}

.page-about .tl__item:hover .tl__title { color: var(--cyan); }

.page-about .tl__text {
  margin: 0;
  font-size: var(--t-0);
  line-height: 1.7;
  color: var(--ice);
  max-width: 62ch;
}

/* ---------- 05 使用场景 ---------- */
.page-about .who {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(14px, 2.4vw, 20px);
}

.page-about .who__item {
  position: relative;
  background: var(--ripple);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(18px, 2.8vw, 26px);
  overflow: hidden;
}

.page-about .who__item::after {
  content: "";
  position: absolute;
  right: -40px;
  bottom: -40px;
  width: 120px;
  height: 120px;
  border-radius: var(--pill);
  background: radial-gradient(circle, rgba(53, 224, 200, 0.28) 0%, rgba(53, 224, 200, 0) 70%);
}

.page-about .who__no {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  letter-spacing: 0.06em;
  color: var(--orange);
  margin-bottom: 10px;
}

.page-about .who__title {
  margin: 0 0 8px;
  font-size: var(--t-1);
  font-weight: 400;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.page-about .who__text {
  position: relative;
  z-index: 1;
  margin: 0;
  font-size: var(--t--1);
  line-height: 1.72;
  color: var(--ink-2);
}

.page-about .audience__foot {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--t--1);
  letter-spacing: 0.03em;
  color: var(--slate);
}

@media (min-width: 760px) {
  .page-about .who {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

/* ---------- 06 联系 ---------- */
.page-about .closeout {
  border-top: 1px solid var(--line-inv);
  padding-top: clamp(18px, 2.8vw, 28px);
}

.page-about .closeout__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: clamp(20px, 3vw, 30px);
}

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

.page-about .contact-lines li {
  display: grid;
  grid-template-columns: 52px minmax(0, 1fr);
  gap: 12px;
  align-items: baseline;
  font-size: var(--t--1);
  line-height: 1.65;
  color: var(--ice);
  padding-bottom: 12px;
  border-bottom: 1px solid var(--line-inv);
}

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

.page-about .contact-lines__k {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--cyan);
}

.page-about .contact-note {
  margin: 18px 0 0;
  font-size: var(--t--1);
  line-height: 1.7;
  color: var(--slate);
  color: rgba(191, 215, 232, 0.72);
}

@media (min-width: 760px) {
  .page-about .contact-lines li {
    grid-template-columns: 64px minmax(0, 1fr);
  }
}

/* ---------- 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  .page-about .tl__item::before,
  .page-about .tl__title {
    transition: none;
  }
}
</main>