.page-about {
  --rail-w: 208px;
  --hero-grid-line: rgba(34, 53, 74, 0.55);
  --tint-cyan: rgba(53, 224, 208, 0.08);
  --tint-amber: rgba(245, 165, 36, 0.08);
  display: block;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(120% 90% at 8% -10%, var(--tint-cyan), transparent 62%),
    radial-gradient(90% 70% at 96% 0%, rgba(245, 165, 36, 0.06), transparent 58%),
    var(--ink-900);
  padding: clamp(26px, 4.6vw, 48px) 0 clamp(30px, 5vw, 58px);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, var(--hero-grid-line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--hero-grid-line) 1px, transparent 1px);
  background-size: 88px 88px;
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.75), transparent 80%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.75), transparent 80%);
  pointer-events: none;
}

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

.page-about .about-hero__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(26px, 4vw, 48px);
  margin-top: clamp(22px, 3.4vw, 38px);
}

.page-about .about-hero__eyebrow {
  margin: 0 0 14px;
  font-size: 12.5px;
  letter-spacing: 0.16em;
  color: var(--sage);
}

.page-about .about-hero__title {
  margin: 0 0 20px;
  font-family: var(--font-display);
  font-size: clamp(34px, 7.4vw, 68px);
  line-height: 1.06;
  letter-spacing: -0.02em;
  color: var(--fg);
}

.page-about .about-hero__intro {
  margin: 0 0 14px;
  max-width: 62ch;
  font-size: 16.5px;
  line-height: 1.8;
  color: var(--fg-dim);
}

.page-about .about-hero__intro--sub {
  padding-left: 14px;
  border-left: 2px solid var(--cyan);
  color: var(--fg);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.page-about .about-hero__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0;
  margin: 0;
  border: 1px solid var(--line);
  background: var(--ink-800);
}

.page-about .about-stat {
  padding: 16px 16px 18px;
  border-top: 1px solid var(--line);
  border-right: 1px solid var(--line);
}

.page-about .about-stat:nth-child(2n) {
  border-right: 0;
}

.page-about .about-stat:nth-child(-n + 2) {
  border-top: 0;
}

.page-about .about-stat dt {
  font-size: 12.5px;
  letter-spacing: 0.1em;
  color: var(--fg-dim);
  margin-bottom: 8px;
}

.page-about .about-stat dd {
  margin: 0;
  font-size: clamp(24px, 3.4vw, 32px);
  line-height: 1;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .about-stat__suffix {
  font-size: 13px;
  color: var(--fg-dim);
  margin-left: 6px;
  letter-spacing: 0;
}

/* ---------- 主体：索引轨 + 内容流 ---------- */
.page-about .about-flow {
  padding-top: clamp(28px, 4vw, 46px);
  padding-bottom: clamp(34px, 5vw, 64px);
}

.page-about .about-flow__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(20px, 3vw, 44px);
}

.page-about .about-rail {
  align-self: start;
}

.page-about .about-rail__caption {
  margin: 0 0 10px;
  font-size: 11.5px;
  letter-spacing: 0.18em;
  color: var(--fg-dim);
}

.page-about .about-rail__list {
  display: flex;
  gap: 8px;
  margin: 0;
  padding: 0 0 12px;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-bottom: 1px solid var(--line);
  scrollbar-width: none;
}

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

.page-about .about-rail__link {
  display: flex;
  align-items: baseline;
  gap: 7px;
  padding: 7px 11px;
  border: 1px solid var(--line);
  background: var(--ink-800);
  color: var(--fg-dim);
  text-decoration: none;
  white-space: nowrap;
  font-size: 14px;
  transition: color var(--t-fast) ease, border-color var(--t-fast) ease, background var(--t-fast) ease;
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--fg);
  border-color: var(--cyan);
  background: var(--ink-700);
}

.page-about .about-rail__idx {
  font-size: 11.5px;
  color: var(--cyan);
  letter-spacing: 0.08em;
}

.page-about .about-rail__chip {
  display: none;
  margin: 18px 0 0;
  padding: 9px 11px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--cyan);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--fg-dim);
  background: var(--ink-800);
}

/* ---------- 章节骨架 ---------- */
.page-about .about-block {
  padding: clamp(30px, 4.6vw, 58px) 0;
  border-top: 1px solid var(--line);
}

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

.page-about .about-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 6px 14px;
  align-items: baseline;
  padding-bottom: 14px;
  margin-bottom: clamp(18px, 2.6vw, 28px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-head__idx {
  font-size: 12.5px;
  letter-spacing: 0.14em;
  color: var(--cyan);
}

.page-about .about-head__title {
  margin: 0;
  font-size: clamp(20px, 2.8vw, 29px);
  line-height: 1.3;
  color: var(--fg);
}

.page-about .about-head__note {
  grid-column: 1 / -1;
  margin: 0;
  font-size: 14.5px;
  color: var(--fg-dim);
}

.page-about .about-text p {
  margin: 0 0 16px;
  max-width: 74ch;
  font-size: 16.5px;
  line-height: 1.82;
  color: var(--fg-dim);
}

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

/* ---------- 三栏结构升级 ---------- */
.page-about .upgrade-grid {
  display: grid;
  grid-template-columns: 1fr;
  border: 1px solid var(--line);
  background: var(--ink-800);
}

.page-about .upgrade-col {
  padding: 20px 18px 22px;
  border-top: 3px solid var(--sage);
  border-bottom: 1px solid var(--line);
  transition: border-top-color var(--t-base) ease, background var(--t-base) ease;
}

.page-about .upgrade-col:last-child {
  border-bottom: 0;
}

.page-about .upgrade-col:hover,
.page-about .upgrade-col:focus-within {
  border-top-color: var(--cyan);
  background: var(--ink-700);
}

.page-about .upgrade-col__stage {
  margin: 0 0 8px;
  font-size: 11.5px;
  letter-spacing: 0.18em;
  color: var(--sage);
}

.page-about .upgrade-col__title {
  margin: 0 0 10px;
  font-size: 18px;
  line-height: 1.4;
  color: var(--fg);
}

.page-about .upgrade-col__desc {
  margin: 0 0 16px;
  font-size: 15px;
  line-height: 1.78;
  color: var(--fg-dim);
}

.page-about .upgrade-col__meta {
  margin: 0;
  border-top: 1px solid var(--line);
  padding-top: 12px;
}

.page-about .upgrade-col__meta div {
  display: grid;
  grid-template-columns: 76px minmax(0, 1fr);
  gap: 10px;
  padding: 5px 0;
}

.page-about .upgrade-col__meta dt {
  font-size: 12.5px;
  color: var(--sage);
  letter-spacing: 0.06em;
}

.page-about .upgrade-col__meta dd {
  margin: 0;
  font-size: 14px;
  line-height: 1.66;
  color: var(--fg);
}

/* ---------- 图片块 ---------- */
.page-about .about-figure {
  margin: clamp(22px, 3.4vw, 36px) 0 0;
}

.page-about .about-figure__frame {
  border: 1px solid var(--line);
  background: var(--ink-800);
  overflow: hidden;
}

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

.page-about .about-figure__cap {
  margin-top: 10px;
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--fg-dim);
  padding-left: 12px;
  border-left: 2px solid var(--line);
}

/* ---------- 运营属地 ---------- */
.page-about .locale-block {
  margin-top: 22px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--amber);
  background: var(--ink-800);
  padding: 18px 18px 20px;
}

.page-about .locale-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  margin: 0;
}

.page-about .locale-item {
  display: grid;
  grid-template-columns: 1fr;
  gap: 4px;
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .locale-item:first-child {
  padding-top: 0;
}

.page-about .locale-item dt {
  font-size: 12.5px;
  letter-spacing: 0.12em;
  color: var(--sage);
}

.page-about .locale-item dd {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.7;
  color: var(--fg);
}

.page-about .locale-item dd.t-mono {
  color: var(--amber);
  font-variant-numeric: tabular-nums;
}

.page-about .locale-block__note {
  margin: 16px 0 0;
  font-size: 13.5px;
  line-height: 1.74;
  color: var(--fg-dim);
}

/* ---------- 团队与节奏 ---------- */
.page-about .team-rows {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.page-about .team-row {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 4px 14px;
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .team-row__idx {
  grid-row: span 2;
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--cyan);
  padding-top: 3px;
}

.page-about .team-row__name {
  margin: 0;
  font-size: 17px;
  color: var(--fg);
}

.page-about .team-row__desc {
  margin: 6px 0 0;
  grid-column: 2;
  font-size: 15px;
  line-height: 1.78;
  color: var(--fg-dim);
}

.page-about .cadence {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  margin-top: 22px;
  border: 1px solid var(--line);
  background:
    linear-gradient(90deg, var(--tint-cyan), transparent 55%),
    var(--ink-800);
}

.page-about .cadence__item {
  padding: 16px 18px;
  border-bottom: 1px solid var(--line);
}

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

.page-about .cadence__key {
  margin: 0 0 6px;
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--cyan);
}

.page-about .cadence__val {
  margin: 0;
  font-size: 15px;
  line-height: 1.76;
  color: var(--fg);
}

/* ---------- 海岸过渡带 ---------- */
.page-about .about-coast {
  position: relative;
  margin: clamp(30px, 4.6vw, 56px) 0 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  overflow: hidden;
}

.page-about .about-coast img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  opacity: 0.5;
  filter: saturate(0.7);
}

.page-about .about-coast__cap {
  position: absolute;
  left: 0;
  bottom: 0;
  max-width: 100%;
  padding: 10px 16px;
  background: rgba(11, 22, 34, 0.82);
  border-top: 1px solid var(--line);
  border-right: 1px solid var(--line);
  font-size: 13px;
  line-height: 1.6;
  color: var(--fg-dim);
}

/* ---------- 里程碑时间轴 ---------- */
.page-about .about-block--milestone {
  border-top: 0;
}

.page-about .milestone-list {
  margin: 0;
  padding: 0 0 0 22px;
  list-style: none;
  border-left: 1px solid var(--line);
}

.page-about .milestone {
  position: relative;
  padding: 0 0 clamp(24px, 3.4vw, 38px);
}

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

.page-about .milestone::before {
  content: "";
  position: absolute;
  left: -27px;
  top: 5px;
  width: 9px;
  height: 9px;
  background: var(--ink-900);
  border: 1px solid var(--sage);
  transition: background var(--t-base) ease, border-color var(--t-base) ease, box-shadow var(--t-base) ease;
}

.page-about .milestone.is-current::before {
  background: var(--cyan);
  border-color: var(--cyan);
  box-shadow: 0 0 0 4px rgba(53, 224, 208, 0.12);
}

.page-about .milestone__phase {
  margin: 0 0 6px;
  font-size: 11.5px;
  letter-spacing: 0.16em;
  color: var(--sage);
}

.page-about .milestone.is-current .milestone__phase {
  color: var(--cyan);
}

.page-about .milestone__title {
  margin: 0 0 8px;
  font-size: 17.5px;
  line-height: 1.4;
  color: var(--fg);
}

.page-about .milestone__desc {
  margin: 0;
  max-width: 68ch;
  font-size: 15px;
  line-height: 1.78;
  color: var(--fg-dim);
}

.page-about .milestone__more {
  margin-top: 12px;
  border: 1px solid var(--line);
  background: var(--ink-800);
}

.page-about .milestone__more summary {
  list-style: none;
  cursor: pointer;
  padding: 10px 14px;
  font-size: 13.5px;
  color: var(--link);
  letter-spacing: 0.02em;
}

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

.page-about .milestone__more summary::after {
  content: " ＋";
  color: var(--cyan);
}

.page-about .milestone__more[open] summary::after {
  content: " －";
}

.page-about .milestone__more p {
  margin: 0;
  padding: 0 14px 14px;
  font-size: 14px;
  line-height: 1.76;
  color: var(--fg-dim);
  border-top: 1px solid var(--line);
  padding-top: 12px;
}

/* ---------- 协作生态 ---------- */
.page-about .eco-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  border: 1px solid var(--line);
}

.page-about .eco-card {
  padding: 18px 18px 20px;
  border-bottom: 1px solid var(--line);
  background: var(--ink-800);
  transition: background var(--t-base) ease;
}

.page-about .eco-card:last-child {
  border-bottom: 0;
}

.page-about .eco-card:hover {
  background: var(--ink-700);
}

.page-about .eco-card__tag {
  display: inline-block;
  margin: 0 0 10px;
  padding: 4px 9px;
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--fg);
  background: rgba(126, 148, 134, 0.22);
  border-left: 3px solid var(--sage);
}

.page-about .eco-card__title {
  margin: 0 0 8px;
  font-size: 17px;
  color: var(--fg);
}

.page-about .eco-card__desc {
  margin: 0;
  font-size: 15px;
  line-height: 1.76;
  color: var(--fg-dim);
}

.page-about .eco-contact {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  margin-top: 22px;
  padding: 18px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--cyan);
  background: var(--ink-800);
}

.page-about .eco-contact__text {
  flex: 1 1 320px;
  margin: 0;
  font-size: 15px;
  line-height: 1.76;
  color: var(--fg-dim);
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  border-top: 1px solid var(--line);
  background: var(--ink-800);
  padding: clamp(30px, 4.4vw, 54px) 0 clamp(38px, 5vw, 62px);
}

.page-about .about-next__title {
  margin: 0 0 22px;
  font-size: clamp(19px, 2.4vw, 24px);
  color: var(--fg);
}

.page-about .about-next__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  border-top: 1px solid var(--line);
}

.page-about .next-link {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 6px 14px;
  padding: 18px 4px;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
  transition: background var(--t-fast) ease;
}

.page-about .next-link:hover,
.page-about .next-link:focus-visible {
  background: var(--ink-700);
}

.page-about .next-link__idx {
  grid-row: span 2;
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--cyan);
  padding-top: 3px;
}

.page-about .next-link__title {
  font-size: 16.5px;
  color: var(--fg);
}

.page-about .next-link:hover .next-link__title {
  color: var(--cyan);
}

.page-about .next-link__desc {
  font-size: 14.5px;
  line-height: 1.72;
  color: var(--fg-dim);
}

/* ---------- 中屏 ---------- */
@media (min-width: 700px) {
  .page-about .about-hero__stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-stat:nth-child(2n) {
    border-right: 1px solid var(--line);
  }

  .page-about .about-stat:nth-child(3n) {
    border-right: 0;
  }

  .page-about .about-stat:nth-child(-n + 3) {
    border-top: 0;
  }

  .page-about .about-stat:nth-child(4) {
    border-top: 1px solid var(--line);
  }

  .page-about .locale-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: 24px;
  }

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

  .page-about .cadence__item {
    border-bottom: 0;
    border-right: 1px solid var(--line);
  }

  .page-about .cadence__item:last-child {
    border-right: 0;
  }

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

  .page-about .eco-card {
    border-bottom: 0;
    border-right: 1px solid var(--line);
  }

  .page-about .eco-card:last-child {
    border-right: 0;
  }

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

  .page-about .next-link {
    border-bottom: 0;
    border-right: 1px solid var(--line);
    padding: 20px 16px;
  }

  .page-about .next-link:last-child {
    border-right: 0;
  }
}

/* ---------- 桌面 ---------- */
@media (min-width: 960px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.45fr) minmax(0, 1fr);
    align-items: start;
  }

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

  .page-about .about-stat:nth-child(2n) {
    border-right: 0;
  }

  .page-about .about-stat:nth-child(3n) {
    border-right: 1px solid var(--line);
  }

  .page-about .about-stat:nth-child(-n + 3) {
    border-top: 1px solid var(--line);
  }

  .page-about .about-stat:nth-child(-n + 2) {
    border-top: 0;
  }

  .page-about .about-flow__grid {
    grid-template-columns: var(--rail-w) minmax(0, 1fr);
    gap: clamp(30px, 3.6vw, 54px);
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: 132px;
  }

  .page-about .about-rail__list {
    display: block;
    overflow: visible;
    padding: 0 0 0 16px;
    border-bottom: 0;
    border-left: 1px solid var(--line);
  }

  .page-about .about-rail__item {
    position: relative;
    padding: 0 0 18px;
  }

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

  .page-about .about-rail__item::before {
    content: "";
    position: absolute;
    left: -21px;
    top: 12px;
    width: 8px;
    height: 8px;
    background: var(--ink-900);
    border: 1px solid var(--sage);
    transition: background var(--t-base) ease, border-color var(--t-base) ease;
  }

  .page-about .about-rail__item:hover::before {
    background: var(--cyan);
    border-color: var(--cyan);
  }

  .page-about .about-rail__link {
    border: 0;
    background: transparent;
    padding: 5px 0;
  }

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

  .page-about .about-rail__chip {
    display: block;
  }

  .page-about .about-head {
    grid-template-columns: auto minmax(0, 1fr) auto;
    gap: 6px 16px;
  }

  .page-about .about-head__note {
    grid-column: 3;
    grid-row: 1;
    max-width: 34ch;
    text-align: right;
    align-self: center;
    font-size: 14px;
  }

  .page-about .about-stat dd {
    font-size: 30px;
  }

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

  .page-about .upgrade-col {
    border-top-width: 3px;
    border-bottom: 0;
    border-right: 1px solid var(--line);
    padding: 22px 20px 24px;
  }

  .page-about .upgrade-col:last-child {
    border-right: 0;
  }

  .page-about .upgrade-col + .upgrade-col {
    border-left: 0;
  }

  .page-about .about-figure--wide .about-figure__frame {
    max-width: 100%;
  }

  .page-about .team-row {
    grid-template-columns: 34px 190px minmax(0, 1fr);
    gap: 0 22px;
    align-items: baseline;
  }

  .page-about .team-row__idx {
    grid-row: span 1;
  }

  .page-about .team-row__desc {
    grid-column: 3;
    margin-top: 0;
  }
}

@media (min-width: 1200px) {
  .page-about .about-hero__intro {
    font-size: 17px;
  }
}