.page-about {
  --about-pad: clamp(42px, 7vw, 104px);
  --about-rule: 1px solid var(--line);
  display: block;
  max-width: var(--shell-max);
  margin-inline: auto;
  padding-inline: var(--shell-pad);
  background: var(--ink);
  color: var(--silver);
}

/* ---------- Hero ---------- */
.page-about .about-hero {
  display: grid;
  gap: clamp(24px, 4vw, 48px);
  padding-block: clamp(28px, 4vw, 56px) clamp(34px, 5vw, 68px);
  border-bottom: var(--about-rule);
}

.page-about .about-hero__text {
  max-width: 720px;
}

.page-about .about-hero__text .eyebrow {
  margin: 0 0 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--cyan);
  text-transform: none;
}

.page-about .about-hero h1 {
  margin: 0 0 clamp(16px, 2.4vw, 28px);
  font-size: clamp(34px, 6.2vw, 76px);
  font-weight: 900;
  letter-spacing: -.02em;
  line-height: 1.08;
  color: var(--paper);
}

.page-about .about-hero__lede {
  margin: 0 0 clamp(22px, 3vw, 34px);
  max-width: 640px;
  font-size: clamp(16px, 1.6vw, 18px);
  line-height: 1.8;
  color: var(--silver);
}

.page-about .about-hero__facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-hero__facts li {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 14px 16px;
  background: var(--panel);
}

.page-about .about-hero__facts .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(20px, 2.4vw, 28px);
  line-height: 1;
  color: var(--cyan);
}

.page-about .about-hero__facts li > span:last-child {
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--silver);
}

.page-about .about-hero__figure {
  margin: 0;
  border: 1px solid var(--line);
  background: var(--panel);
}

.page-about .about-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 14 / 9;
  object-fit: cover;
  clip-path: polygon(0 0, 100% 0, 100% 88%, 90% 100%, 0 100%);
}

.page-about .about-hero__figure figcaption {
  padding: 10px 12px;
  border-top: 1px solid var(--line);
  color: var(--silver);
}

/* ---------- 页内索引 ---------- */
.page-about .about-index {
  display: flex;
  flex-wrap: nowrap;
  overflow-x: auto;
  border-bottom: var(--about-rule);
  scrollbar-width: thin;
}

.page-about .about-index a {
  flex: 0 0 auto;
  padding: 14px clamp(12px, 1.6vw, 22px);
  border-right: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--silver);
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--t-fast), background-color var(--t-fast), box-shadow var(--t-fast);
}

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

.page-about .about-index a:hover {
  color: var(--cyan);
  background: rgba(92, 242, 200, .06);
}

.page-about .about-index a[aria-current="true"] {
  color: var(--cyan);
  box-shadow: inset 0 -1px 0 0 var(--cyan);
}

.page-about .about-index a:focus-visible {
  outline: 1px solid var(--cyan);
  outline-offset: -1px;
}

/* ---------- 通用章节骨架 ---------- */
.page-about .about-section {
  padding-block: var(--about-pad);
  border-bottom: var(--about-rule);
}

.page-about .about-section__inner {
  display: grid;
  gap: clamp(18px, 2.6vw, 34px);
}

.page-about .about-section__meta {
  display: flex;
  align-items: flex-start;
  gap: 14px;
}

.page-about .about-section__meta .annotation--v {
  display: none;
}

.page-about .about-section__no {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .12em;
  color: var(--cyan);
}

.page-about .about-section__body {
  max-width: 900px;
}

.page-about .about-section__body h2 {
  margin: 0 0 clamp(14px, 1.8vw, 22px);
  font-size: clamp(26px, 3.4vw, 44px);
  font-weight: 900;
  letter-spacing: -.02em;
  line-height: 1.16;
  color: var(--paper);
}

.page-about .about-section__lead {
  margin: 0;
  max-width: 680px;
  font-size: clamp(16px, 1.7vw, 18px);
  line-height: 1.8;
  color: var(--silver);
}

/* ---------- 四步流程 ---------- */
.page-about .flow-grid {
  display: grid;
  gap: 1px;
  margin: clamp(24px, 3.4vw, 40px) 0 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .flow-step {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: clamp(18px, 2vw, 26px);
  background: var(--panel);
}

.page-about .flow-step__no {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--orange);
}

.page-about .flow-step h3 {
  margin: 0;
  font-size: 18px;
  font-weight: 700;
  letter-spacing: -.01em;
  color: var(--paper);
}

.page-about .flow-step > p {
  margin: 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--silver);
}

.page-about .flow-step__more {
  margin-top: auto;
  padding-top: 10px;
  border-top: 1px solid var(--line-soft);
}

.page-about .flow-step__more summary {
  cursor: pointer;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--cyan);
}

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

.page-about .flow-step__more summary::after {
  content: " ＋";
}

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

.page-about .flow-step__more summary:focus-visible {
  outline: 1px solid var(--cyan);
  outline-offset: 3px;
}

.page-about .flow-step__more ul {
  margin: 10px 0 0;
  padding-left: 16px;
  font-size: 13px;
  line-height: 1.72;
  color: var(--silver);
}

/* ---------- 两条拆解线 ---------- */
.page-about .lines-split {
  display: grid;
  gap: clamp(22px, 3vw, 40px);
  margin-top: clamp(24px, 3.4vw, 40px);
}

.page-about .line-card {
  padding-top: 18px;
  margin-bottom: clamp(20px, 2.6vw, 30px);
  border-top: 1px solid var(--line);
}

.page-about .line-card h3 {
  margin: 0 0 10px;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: .01em;
  color: var(--cyan-soft);
}

.page-about .line-card p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--silver);
}

.page-about .lines-split__note {
  margin: 0;
  padding-left: 14px;
  border-left: 1px solid var(--orange);
  font-size: 14px;
  line-height: 1.78;
  color: var(--silver);
}

.page-about .lines-split__figure {
  margin: 0;
  border: 1px solid var(--line);
  background: var(--panel);
}

.page-about .lines-split__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 12 / 7.5;
  object-fit: cover;
}

.page-about .lines-split__figure figcaption {
  padding: 10px 12px;
  border-top: 1px solid var(--line);
  color: var(--silver);
}

/* ---------- 口径手册 ---------- */
.page-about .manual-head {
  display: grid;
  gap: clamp(20px, 3vw, 32px);
  margin-top: clamp(20px, 2.6vw, 30px);
}

.page-about .manual-head__figure {
  margin: 0;
  border: 1px solid var(--line);
  background: var(--panel);
}

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

.page-about .manual-head__figure figcaption {
  padding: 10px 12px;
  border-top: 1px solid var(--line);
  color: var(--silver);
}

.page-about .manual-timeline {
  margin: clamp(26px, 3.6vw, 44px) 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.page-about .manual-item {
  display: grid;
  gap: 8px;
  padding: clamp(18px, 2.2vw, 26px) 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .manual-item__ver {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--silver);
}

.page-about .manual-item h3 {
  margin: 0;
  font-size: 17px;
  font-weight: 700;
  color: var(--paper);
}

.page-about .manual-item p {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--silver);
}

.page-about .manual-item--current {
  border-bottom-color: var(--cyan);
}

.page-about .manual-item--current .manual-item__ver {
  color: var(--cyan);
}

.page-about .manual-item--current h3 {
  color: var(--cyan-soft);
}

.page-about .manual-item__badge {
  display: inline-block;
  margin-left: 8px;
  padding: 1px 6px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .08em;
  color: var(--ink);
  background: var(--cyan);
}

/* ---------- 团队分工 ---------- */
.page-about .team-bars {
  display: grid;
  gap: clamp(20px, 2.6vw, 30px);
  margin: clamp(26px, 3.6vw, 44px) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .team-bar__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px 16px;
  margin-bottom: 10px;
}

.page-about .team-bar__head > span:first-child {
  font-size: 16px;
  font-weight: 700;
  color: var(--paper);
}

.page-about .team-bar__head .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 14px;
  letter-spacing: .04em;
  color: var(--cyan);
}

.page-about .team-bar__track {
  display: flex;
  align-items: center;
  height: 28px;
  background: var(--panel);
  border: 1px solid var(--line);
}

.page-about .team-bar__fill {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  height: 100%;
  padding-right: 8px;
  overflow: hidden;
  white-space: nowrap;
  background: var(--cyan);
  color: var(--ink);
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  font-weight: 700;
}

.page-about .team-bar__fill--data { width: 50%; }
.page-about .team-bar__fill--content { width: 32%; }
.page-about .team-bar__fill--visual { width: 18%; background: var(--cyan-deep); color: var(--paper); }

.page-about .team-bar p {
  margin: 10px 0 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--silver);
}

.page-about .team-schedule {
  margin: clamp(28px, 3.4vw, 42px) 0 0;
  padding-top: clamp(18px, 2.2vw, 26px);
  border-top: 1px solid var(--line);
  font-size: 15px;
  line-height: 1.85;
  color: var(--silver);
}

.page-about .team-schedule .annotation {
  margin-right: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .12em;
  color: var(--orange);
}

/* ---------- 里程碑 ---------- */
.page-about .mile-timeline {
  margin: clamp(26px, 3.6vw, 44px) 0 0;
  padding: 0 0 0 clamp(20px, 3vw, 34px);
  list-style: none;
  border-left: 1px solid var(--line);
}

.page-about .mile-item {
  position: relative;
  padding-bottom: clamp(22px, 3vw, 34px);
}

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

.page-about .mile-item::before {
  content: "";
  position: absolute;
  top: 9px;
  left: calc(-1 * clamp(20px, 3vw, 34px) - 4px);
  width: 7px;
  height: 7px;
  background: var(--ink);
  border: 1px solid var(--line);
}

.page-about .mile-item:last-child::before {
  background: var(--orange);
  border-color: var(--orange);
}

.page-about .mile-year {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(20px, 2.4vw, 28px);
  line-height: 1;
  letter-spacing: -.01em;
  color: var(--cyan);
}

.page-about .mile-item h3 {
  margin: 0 0 8px;
  font-size: 16px;
  font-weight: 700;
  color: var(--paper);
}

.page-about .mile-item p {
  margin: 0;
  max-width: 660px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--silver);
}

/* ---------- 边界（浅色反相） ---------- */
.page-about .about-section--invert {
  padding-inline: clamp(18px, 3vw, 48px);
  background: var(--paper);
  color: var(--paper-ink);
  border-bottom: 0;
}

.page-about .about-section--invert .about-section__no {
  color: var(--cyan-deep);
}

.page-about .about-section--invert .about-section__body h2 {
  color: var(--paper-ink);
}

.page-about .about-section--invert .about-section__lead {
  color: #2C4340;
}

.page-about .boundary-list {
  display: grid;
  gap: 1px;
  margin: clamp(24px, 3vw, 38px) 0 0;
  padding: 0;
  list-style: none;
  background: rgba(19, 33, 29, .16);
  border: 1px solid rgba(19, 33, 29, .16);
}

.page-about .boundary-list li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 14px;
  align-items: start;
  padding: clamp(18px, 2.2vw, 26px);
  background: var(--paper);
}

.page-about .boundary-list .num {
  padding-top: 2px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--cyan-deep);
}

.page-about .boundary-list p {
  margin: 0;
  font-size: 15px;
  line-height: 1.82;
  color: var(--paper-ink);
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding-block: clamp(26px, 3.6vw, 48px);
}

.page-about .about-next__label {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--silver);
}

.page-about .about-next__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.page-about .about-next__links a {
  padding: 10px 16px;
  border: 1px solid var(--line);
  font-size: 13px;
  line-height: 1.5;
  color: var(--cyan-soft);
  text-decoration: none;
  transition: border-color var(--t-fast), color var(--t-fast), background-color var(--t-fast);
}

.page-about .about-next__links a:hover {
  border-color: var(--cyan);
  background: var(--cyan);
  color: var(--ink);
}

.page-about .about-next__links a:focus-visible {
  outline: 1px solid var(--cyan);
  outline-offset: 2px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 560px) {
  .page-about .about-hero__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-next {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
}

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

  .page-about .manual-item {
    grid-template-columns: 110px minmax(0, .9fr) minmax(0, 1.3fr);
    gap: clamp(14px, 2vw, 28px);
    align-items: start;
  }

  .page-about .mile-item {
    display: grid;
    grid-template-columns: 104px minmax(0, 1fr);
    gap: 4px clamp(16px, 2vw, 28px);
    align-items: start;
  }

  .page-about .mile-year {
    margin-bottom: 0;
    padding-top: 2px;
  }

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

  .page-about .boundary-list li:last-child {
    grid-column: span 2;
  }
}

@media (min-width: 880px) {
  .page-about .about-index {
    flex-wrap: wrap;
    overflow: visible;
  }

  .page-about .about-index a {
    flex: 1 1 auto;
    text-align: center;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 1.12fr) minmax(0, .88fr);
    align-items: end;
    column-gap: clamp(32px, 4vw, 72px);
  }

  .page-about .about-section__inner {
    grid-template-columns: minmax(96px, 150px) minmax(0, 1fr);
    column-gap: clamp(28px, 4vw, 72px);
  }

  .page-about .about-section__meta {
    flex-direction: column;
    gap: 14px;
    position: sticky;
    top: calc(var(--header-h) + 24px);
    align-self: start;
  }

  .page-about .about-section__meta .annotation--v {
    display: block;
  }

  .page-about .lines-split {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
    align-items: start;
  }

  .page-about .manual-head {
    grid-template-columns: minmax(0, 1fr) minmax(0, 300px);
    align-items: start;
  }
}

@media (min-width: 1120px) {
  .page-about .flow-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .manual-head {
    grid-template-columns: minmax(0, 1fr) minmax(0, 340px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-index a,
  .page-about .about-next__links a {
    transition: none;
  }
}