.page-about {
  --about-text: #D7E2EA;
  --about-accent-ink: #A8410F;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-body);
  overflow-x: hidden;
}

.page-about .about-top {
  padding-top: clamp(1.25rem, 4vw, 2.25rem);
}

.page-about .about-hero {
  padding-block: clamp(2rem, 6vw, 4rem) clamp(2.75rem, 7vw, 5rem);
}

.page-about .about-hero h1 {
  margin: 1rem 0 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2.35rem, 8vw, 5.25rem);
  line-height: 1.03;
  letter-spacing: -0.03em;
  max-width: 16ch;
}

.page-about .about-hero__lede {
  margin: clamp(1.25rem, 3vw, 2rem) 0 0;
  max-width: 58ch;
  font-size: clamp(1rem, 1.7vw, 1.1875rem);
  line-height: 1.8;
  color: var(--about-text);
}

.page-about .about-hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.75rem;
  margin: clamp(1.5rem, 4vw, 2.5rem) 0 0;
  padding: 0.9rem 0 0;
  list-style: none;
  border-top: 1px solid var(--line-soft);
  font-family: var(--font-mono);
  font-size: var(--t-12);
  letter-spacing: 0.1em;
  color: var(--steel-400);
}

.page-about .about-hero__meta-item {
  position: relative;
  padding-left: 0.9rem;
}

.page-about .about-hero__meta-item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.45em;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--accent-alt);
}

/* ---- 章节骨架 ---- */
.page-about .chapter {
  padding-block: clamp(2.5rem, 6vw, 4.5rem);
  border-top: 1px solid var(--line-soft);
}

.page-about .chapter__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(1.5rem, 4vw, 2.5rem);
}

.page-about .chapter__side {
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
  align-items: flex-start;
}

.page-about .chapter__num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: clamp(2.25rem, 6vw, 3.5rem);
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--signal-orange);
  font-variant-numeric: tabular-nums;
}

.page-about .chapter__kicker {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--t-12);
  letter-spacing: 0.16em;
  color: var(--steel-400);
}

.page-about .chapter__note {
  margin: 0;
  padding-left: 0.9rem;
  border-left: 2px solid var(--signal-orange);
  font-family: var(--font-serif);
  font-size: var(--t-14);
  line-height: 1.85;
  color: var(--steel-400);
  max-width: 26ch;
}

.page-about .chapter__main {
  min-width: 0;
}

.page-about .chapter__title {
  margin: 0 0 1.25rem;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  line-height: 1.18;
  letter-spacing: -0.02em;
  color: var(--fg);
}

.page-about .chapter__main p {
  margin: 0 0 1rem;
  max-width: 68ch;
  font-size: var(--t-16);
  line-height: 1.85;
  color: var(--about-text);
}

.page-about .chapter__main p strong {
  color: var(--fg);
  font-weight: 600;
}

.page-about .chapter__link {
  margin-top: 1.5rem;
}

/* ---- 三个动作 ---- */
.page-about .principles {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.25rem;
  margin: 1.75rem 0 0;
}

.page-about .principle {
  padding-top: 1rem;
  border-top: 1px solid var(--line);
}

.page-about .principle__no {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--t-12);
  letter-spacing: 0.14em;
  color: var(--accent-alt);
}

.page-about .principle__title {
  margin: 0.5rem 0 0.5rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.0625rem;
  color: var(--fg);
}

.page-about .principle p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: var(--about-text);
}

/* ---- 图片 ---- */
.page-about .figure-wide {
  margin: clamp(1.75rem, 4vw, 2.75rem) 0 0;
}

.page-about .figure-wide .media__img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--r-md);
  border: 1px solid var(--line-soft);
  background: var(--bg-panel);
}

.page-about .figure-wide .media__caption {
  margin-top: 0.7rem;
  font-family: var(--font-mono);
  font-size: var(--t-12);
  letter-spacing: 0.03em;
  line-height: 1.7;
  color: var(--steel-400);
}

/* ---- 四类人 ---- */
.page-about .who-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1rem;
  margin-top: 1.75rem;
}

.page-about .who-card {
  padding: 1.15rem 1.15rem 1.35rem;
  border: 1px solid var(--line-soft);
  border-radius: var(--r-md);
  background: linear-gradient(180deg, rgba(23, 63, 92, 0.42), rgba(6, 24, 38, 0));
}

.page-about .who-card__tag {
  display: block;
  margin-bottom: 0.6rem;
  font-family: var(--font-mono);
  font-size: var(--t-12);
  letter-spacing: 0.12em;
  color: var(--accent-alt);
}

.page-about .who-card__title {
  margin: 0 0 0.55rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.0625rem;
  line-height: 1.4;
  color: var(--fg);
}

.page-about .who-card p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: var(--about-text);
}

/* ---- 六栏目 ---- */
.page-about .linkage {
  margin: 1.5rem 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
}

.page-about .linkage li {
  display: grid;
  grid-template-columns: 2rem minmax(0, 1fr);
  gap: 0.75rem;
  padding: 1rem 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .linkage__no {
  font-family: var(--font-mono);
  font-size: var(--t-14);
  font-weight: 600;
  color: var(--accent-alt);
  font-variant-numeric: tabular-nums;
}

.page-about .linkage__name {
  margin: 0 0 0.3rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1rem;
  color: var(--fg);
}

.page-about .linkage p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--about-text);
}

/* ---- 时间线 ---- */
.page-about .timeline {
  position: relative;
  margin-top: 1.75rem;
  padding-left: 1.75rem;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 1.1rem;
  bottom: 1.1rem;
  width: 1px;
  background: linear-gradient(180deg, var(--accent-alt), var(--line-soft));
}

.page-about .timeline__item {
  position: relative;
}

.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: -1.75rem;
  top: 1.15rem;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--accent-alt);
  box-shadow: 0 0 0 4px rgba(79, 209, 176, 0.14);
}

.page-about .timeline .disclosure__heading {
  margin: 0;
}

.page-about .timeline .disclosure__trigger {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.4rem 0.8rem;
  width: 100%;
  padding: 0.85rem 0;
  background: none;
  border: 0;
  border-bottom: 1px solid var(--line-soft);
  text-align: left;
  color: var(--fg);
  font-family: var(--font-body);
  cursor: pointer;
  transition: color 160ms var(--ease);
}

.page-about .timeline .disclosure__trigger:hover .timeline__label,
.page-about .timeline .disclosure__trigger:focus-visible .timeline__label {
  color: var(--accent-alt);
}

.page-about .timeline .disclosure__trigger:focus-visible {
  outline: 2px solid var(--signal-orange);
  outline-offset: 3px;
}

.page-about .timeline .disclosure__trigger[aria-expanded="true"] .timeline__label {
  color: var(--warm-gold);
}

.page-about .timeline__stage {
  font-family: var(--font-mono);
  font-size: var(--t-12);
  letter-spacing: 0.08em;
  color: var(--steel-400);
  font-variant-numeric: tabular-nums;
}

.page-about .timeline__label {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.0625rem;
  transition: color 160ms var(--ease);
}

.page-about .timeline .disclosure__icon {
  margin-left: auto;
  color: var(--steel-400);
}

.page-about .timeline .disclosure__panel {
  padding: 0.85rem 0 1.25rem;
}

.page-about .timeline .disclosure__panel p {
  margin: 0;
  max-width: 62ch;
  font-size: 0.9375rem;
  line-height: 1.85;
  color: var(--about-text);
}

/* ---- 服务承诺（浅色纸感分区） ---- */
.page-about .commit-band {
  background: var(--paper-100);
  color: var(--paper-ink);
  padding-block: clamp(2.75rem, 7vw, 5rem);
}

.page-about .commit-band .chapter__num {
  color: var(--about-accent-ink);
}

.page-about .commit-band .chapter__kicker {
  color: #5B7182;
}

.page-about .commit-band .chapter__title {
  color: var(--paper-ink);
}

.page-about .commit-band .chapter__main p {
  color: #33474F;
}

.page-about .commit-band .chapter__grid {
  border-top: 1px solid rgba(27, 42, 53, 0.16);
  padding-top: clamp(1.75rem, 4vw, 2.5rem);
}

.page-about .metrics {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.25rem;
  margin-top: 1.75rem;
}

.page-about .metric {
  padding: 1rem 0 0;
  border-top: 2px solid rgba(27, 42, 53, 0.22);
}

.page-about .metric__num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: clamp(1.6rem, 4.5vw, 2.25rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--about-accent-ink);
  font-variant-numeric: tabular-nums;
}

.page-about .metric__label {
  display: block;
  margin-top: 0.4rem;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: #3C4F5C;
}

/* ---- 收尾 ---- */
.page-about .about-cta {
  padding-block: clamp(2.75rem, 7vw, 4.5rem);
  border-top: 1px solid var(--line-soft);
}

.page-about .about-cta__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.5rem, 4.5vw, 2.25rem);
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--fg);
}

.page-about .about-cta__text {
  margin: 1rem 0 0;
  max-width: 60ch;
  font-size: var(--t-16);
  line-height: 1.85;
  color: var(--about-text);
}

.page-about .cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.75rem;
}

/* ---- 断点 ---- */
@media (min-width: 640px) {
  .page-about .who-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .metrics {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.5rem;
  }
}

@media (min-width: 760px) {
  .page-about .principles {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.5rem;
  }
}

@media (min-width: 900px) {
  .page-about .chapter__grid {
    grid-template-columns: minmax(0, 0.8fr) minmax(0, 2.2fr);
    gap: clamp(2rem, 5vw, 4.5rem);
  }

  .page-about .chapter__side {
    position: sticky;
    top: calc(var(--header-h) + 2.5rem);
    align-self: start;
  }

  .page-about .linkage {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: 2.5rem;
  }

  .page-about .commit-band .chapter__side {
    position: static;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .timeline .disclosure__trigger,
  .page-about .timeline__label {
    transition: none;
  }
}