.page-about {
  --about-axis: 52px;
  --about-gutter: 14px;
  padding-bottom: 72px;
}

@media (min-width: 600px) {
  .page-about {
    --about-axis: 76px;
    --about-gutter: 24px;
  }
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  padding: 20px 0 0;
}

.page-about .about-hero__grid {
  display: grid;
  gap: 30px;
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: 56px;
    align-items: center;
  }
}

.page-about .about-hero__kicker {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  margin: 0 0 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--cyan-deep);
}

.page-about .about-hero__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(28px, 5.4vw, 52px);
  line-height: 1.16;
  letter-spacing: 0.04em;
  color: var(--ink-900);
}

.page-about .about-hero__lede {
  margin: 22px 0 0;
  max-width: 36em;
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.85;
  color: var(--ink-700);
}

.page-about .about-hero__quote {
  margin: 0;
  padding: 6px 0 6px 20px;
  border-left: 3px solid var(--cyan-bright);
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(18px, 2.5vw, 26px);
  line-height: 1.62;
  letter-spacing: 0.06em;
  color: var(--ink-900);
}

.page-about .about-hero__figure {
  margin: 40px 0 0;
}

.page-about .about-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 12 / 7;
  object-fit: cover;
  background: var(--paper-50);
}

/* ---------- 时间轴容器 ---------- */

.page-about .about-timeline {
  margin-top: 72px;
}

.page-about .about-timeline__head {
  padding-bottom: 28px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-timeline__kicker {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--gray-500);
}

.page-about .about-timeline__heading {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(23px, 3.3vw, 34px);
  line-height: 1.26;
  letter-spacing: 0.03em;
  color: var(--ink-900);
}

.page-about .stage-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

/* ---------- 阶段块 ---------- */

.page-about .stage {
  --stage-bg: var(--paper-50);
  --stage-fg: var(--ink-900);
  --stage-text: var(--ink-700);
  --stage-muted: var(--gray-500);
  --stage-rule: var(--line);
  --stage-dot: var(--cyan-bright);
  position: relative;
  display: grid;
  grid-template-columns: var(--about-axis) minmax(0, 1fr);
  gap: var(--about-gutter);
  padding: 0 24px;
  background: var(--stage-bg);
  color: var(--stage-fg);
}

@media (min-width: 1080px) {
  .page-about .stage {
    padding-left: max(24px, calc((100% - var(--maxw)) / 2 + 24px));
    padding-right: max(24px, calc((100% - var(--maxw)) / 2 + 24px));
  }
}

.page-about .stage--start {
  --stage-bg: var(--paper-50);
}

.page-about .stage--cycle {
  --stage-bg: var(--paper-100);
}

.page-about .stage--track {
  --stage-bg: var(--amber-paper);
  --stage-rule: #D6C099;
  --stage-dot: var(--amber-deep);
}

.page-about .stage--crew {
  --stage-bg: var(--ink-950);
  --stage-fg: var(--paper-50);
  --stage-text: rgba(245, 239, 228, 0.82);
  --stage-muted: rgba(245, 239, 228, 0.58);
  --stage-rule: rgba(53, 214, 230, 0.3);
  --stage-dot: var(--cyan-bright);
}

.page-about .stage--mile {
  --stage-bg: var(--paper-100);
}

.page-about .stage--partner {
  --stage-bg: var(--cyan-pale);
  --stage-rule: #A8D8DF;
  --stage-dot: var(--cyan-deep);
}

/* 轴线 */

.page-about .stage__axis {
  position: relative;
  align-self: stretch;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding-top: 36px;
}

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

.page-about .stage__no {
  position: relative;
  z-index: 1;
  padding: 3px 6px;
  background: var(--stage-bg);
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--stage-muted);
}

.page-about .stage__when {
  position: relative;
  z-index: 1;
  padding: 2px 5px;
  background: var(--stage-bg);
  font-family: var(--font-display);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.08em;
  line-height: 1.35;
  text-align: center;
  color: var(--stage-muted);
}

@media (min-width: 600px) {
  .page-about .stage__when {
    font-size: 12px;
  }
}

/* 折叠体 */

.page-about .stage__body {
  min-width: 0;
  padding: 34px 0 42px;
}

.page-about .stage__summary {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .stage__summary:focus-visible {
  outline: 2px solid var(--cyan-bright);
  outline-offset: 5px;
}

.page-about .stage__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(19px, 2.5vw, 27px);
  line-height: 1.32;
  letter-spacing: 0.03em;
  color: var(--stage-fg);
}

.page-about .stage__toggle {
  position: relative;
  flex: 0 0 auto;
  width: 28px;
  height: 28px;
  margin-top: 3px;
  border: 1px solid var(--stage-rule);
  transition: border-color 200ms var(--ease), background-color 200ms var(--ease);
}

.page-about .stage__toggle::before,
.page-about .stage__toggle::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  background: var(--stage-muted);
  transform: translate(-50%, -50%);
  transition: transform 200ms var(--ease), opacity 200ms var(--ease);
}

.page-about .stage__toggle::before {
  width: 12px;
  height: 1.5px;
}

.page-about .stage__toggle::after {
  width: 1.5px;
  height: 12px;
}

.page-about .stage__summary:hover .stage__toggle {
  border-color: var(--stage-dot);
}

.page-about .stage__body[open] .stage__toggle::after {
  transform: translate(-50%, -50%) scaleY(0);
  opacity: 0;
}

/* 阶段正文 */

.page-about .stage__content {
  padding-top: 18px;
  max-width: 64ch;
}

.page-about .stage__content p {
  margin: 0 0 16px;
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.85;
  color: var(--stage-text);
}

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

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

.page-about .stage__points li {
  position: relative;
  padding-left: 24px;
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.78;
  color: var(--stage-text);
}

.page-about .stage__points li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.78em;
  width: 13px;
  height: 1.5px;
  background: var(--stage-dot);
}

.page-about .stage__figure {
  margin: 24px 0 0;
  max-width: 520px;
}

.page-about .stage__figure--wide {
  max-width: 640px;
}

.page-about .stage__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

/* ---------- 团队分工面板 ---------- */

.page-about .crew-grid {
  display: grid;
  gap: 1px;
  margin-top: 26px;
  background: rgba(245, 239, 228, 0.16);
  border: 1px solid rgba(245, 239, 228, 0.16);
}

@media (min-width: 640px) {
  .page-about .crew-grid {
    grid-template-columns: 1fr 1fr;
  }
}

.page-about .crew-cell {
  background: var(--ink-950);
  padding: 20px 18px 22px;
  transition: background-color 220ms var(--ease);
}

.page-about .crew-cell:hover {
  background: var(--ink-900);
}

.page-about .crew-cell__head {
  display: flex;
  align-items: center;
  gap: 9px;
  margin-bottom: 10px;
}

.page-about .crew-cell__name {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 17px;
  letter-spacing: 0.04em;
  color: var(--paper-50);
}

.page-about .crew-cell__desc {
  margin: 0;
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.8;
  color: rgba(245, 239, 228, 0.78);
}

.page-about .crew-cell__meta {
  display: block;
  margin-top: 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: rgba(53, 214, 230, 0.88);
}

/* ---------- 节点列表 ---------- */

.page-about .milestone-list {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
}

.page-about .milestone {
  display: grid;
  gap: 6px;
  padding: 16px 0;
  border-bottom: 1px dashed var(--line);
}

.page-about .milestone:first-child {
  border-top: 1px dashed var(--line);
}

@media (min-width: 640px) {
  .page-about .milestone {
    grid-template-columns: 148px minmax(0, 1fr);
    gap: 22px;
    align-items: baseline;
  }
}

.page-about .milestone__when {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.1em;
  color: var(--amber-deep);
}

.page-about .milestone__what {
  margin: 0;
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.8;
  color: var(--stage-text);
}

/* ---------- 延伸索引带 ---------- */

.page-about .about-next {
  margin-top: 76px;
}

.page-about .about-next__heading {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(20px, 2.4vw, 26px);
  letter-spacing: 0.04em;
  color: var(--ink-900);
}

.page-about .about-next__list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

@media (min-width: 720px) {
  .page-about .about-next__list {
    grid-template-columns: 1fr 1fr;
  }
}

.page-about .about-next__link {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 4px 14px;
  padding: 18px 20px 20px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--cyan-bright);
  background: var(--paper-50);
  text-decoration: none;
  transition: background-color 180ms var(--ease), border-color 180ms var(--ease),
    transform 180ms var(--ease);
}

.page-about .about-next__link:hover {
  background: var(--cyan-pale);
  border-color: var(--cyan-deep);
  border-left-color: var(--cyan-deep);
  transform: translateY(-2px);
}

.page-about .about-next__link:focus-visible {
  outline: 2px solid var(--cyan-bright);
  outline-offset: 3px;
}

.page-about .about-next__no {
  grid-row: span 2;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--gray-500);
  padding-top: 3px;
}

.page-about .about-next__name {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 17px;
  letter-spacing: 0.04em;
  color: var(--ink-900);
}

.page-about .about-next__desc {
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.7;
  color: var(--ink-700);
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-next__link {
    transition: background-color 120ms linear, border-color 120ms linear;
  }
  .page-about .about-next__link:hover {
    transform: none;
  }
  .page-about .stage__toggle,
  .page-about .stage__toggle::before,
  .page-about .stage__toggle::after,
  .page-about .crew-cell {
    transition-duration: 120ms;
  }
}