.page-about {
  --about-axis-w: 176px;
  --about-line: var(--line-500);
  padding-bottom: 0;
}

.page-about :focus-visible {
  outline: 2px solid var(--signal-500);
  outline-offset: 3px;
  border-radius: 4px;
}

.page-about .og-breadcrumb {
  padding-top: 8px;
}

/* ---------- Hero ---------- */
.page-about .about-hero {
  position: relative;
  display: grid;
  gap: 36px;
  padding-top: 24px;
  padding-bottom: 72px;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: -24px -20px 0;
  background-image:
    linear-gradient(to right, rgba(46, 55, 104, 0.22) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(46, 55, 104, 0.22) 1px, transparent 1px);
  background-size: 96px 96px;
  -webkit-mask-image: radial-gradient(circle at 72% 42%, #000 0%, transparent 74%);
  mask-image: radial-gradient(circle at 72% 42%, #000 0%, transparent 74%);
  pointer-events: none;
  z-index: 0;
}

.page-about .about-hero > * {
  position: relative;
  z-index: 1;
  min-width: 0;
}

.page-about .about-hero__text {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}

.page-about .about-hero__title {
  margin: 14px 0 0;
  font-size: clamp(2.1rem, 8.2vw, 4.4rem);
  font-weight: 200;
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--text-900);
  max-width: 16ch;
}

.page-about .about-hero__lead {
  margin: 22px 0 0;
  font-size: 16.5px;
  line-height: 1.9;
  color: var(--text-300);
  max-width: 60ch;
}

.page-about .about-stats {
  list-style: none;
  margin: 34px 0 0;
  padding: 20px 0 0;
  width: 100%;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  border-top: 1px solid var(--about-line);
}

.page-about .about-stats li {
  min-width: 0;
}

.page-about .about-stats__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.35rem, 4.6vw, 1.75rem);
  line-height: 1.1;
  color: var(--signal-500);
  font-variant-numeric: tabular-nums;
}

.page-about .about-stats__label {
  display: block;
  margin-top: 6px;
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--text-300);
}

.page-about .about-figure {
  margin: 0;
  position: relative;
  overflow: hidden;
  border: 1px solid var(--about-line);
  border-radius: var(--radius-panel);
  background: linear-gradient(160deg, var(--ink-850) 0%, var(--ink-950) 100%);
  box-shadow: var(--shadow-panel);
}

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

.page-about .about-figure::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(10, 15, 44, 0) 52%, rgba(10, 15, 44, 0.6) 100%);
  pointer-events: none;
}

.page-about .about-figure__caption {
  position: relative;
  z-index: 1;
  padding: 12px 16px;
  border-top: 1px solid var(--about-line);
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.6;
  color: var(--text-300);
}

.page-about .about-hero__figure img {
  aspect-ratio: 16 / 10;
}

/* ---------- Shell & index axis ---------- */
.page-about .about-shell {
  display: grid;
  gap: 20px;
  padding-bottom: 64px;
}

.page-about .about-index {
  align-self: start;
  min-width: 0;
}

.page-about .about-index__label {
  margin: 0;
  font-family: var(--font-narrow);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--text-300);
}

.page-about .about-index__list {
  list-style: none;
  margin: 12px 0 0;
  padding: 0 0 6px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .about-index__list li {
  flex: 0 0 auto;
}

.page-about .about-index__link {
  display: flex;
  gap: 8px;
  align-items: baseline;
  white-space: nowrap;
  padding: 9px 14px;
  border: 1px solid var(--about-line);
  border-radius: var(--radius-pill);
  font-size: 13.5px;
  color: var(--text-300);
  text-decoration: none;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease), background-color 0.18s var(--ease);
}

.page-about .about-index__link:hover {
  color: var(--text-900);
  border-color: var(--cyan-400);
}

.page-about .about-index__num {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: var(--signal-500);
  font-variant-numeric: tabular-nums;
}

/* ---------- Chapters ---------- */
.page-about .about-body {
  min-width: 0;
}

.page-about .about-chapter {
  padding-top: 34px;
  border-top: 1px solid var(--about-line);
  margin-bottom: 64px;
  scroll-margin-top: calc(var(--header-h) + 24px);
}

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

.page-about .about-chapter__head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 6px 16px;
  align-items: start;
  margin-bottom: 24px;
}

.page-about .about-chapter__num {
  grid-column: 1;
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 5.4vw, 2.4rem);
  line-height: 1;
  color: var(--signal-500);
  font-variant-numeric: tabular-nums;
}

.page-about .about-chapter__title {
  grid-column: 2;
  margin: 0;
  font-size: clamp(1.4rem, 4.4vw, 2.05rem);
  font-weight: 300;
  line-height: 1.22;
  letter-spacing: -0.01em;
  color: var(--text-900);
}

.page-about .about-chapter__claim {
  grid-column: 2;
  margin: 12px 0 0;
  padding-left: 14px;
  border-left: 2px solid var(--signal-500);
  font-size: 15px;
  line-height: 1.78;
  color: var(--text-300);
  max-width: 54ch;
}

.page-about .about-chapter__body {
  display: grid;
  gap: 22px;
  min-width: 0;
}

.page-about .about-chapter__body > * {
  min-width: 0;
}

.page-about .about-chapter__body p {
  margin: 0;
  font-size: 16.5px;
  line-height: 1.9;
  color: var(--text-300);
  max-width: 68ch;
}

/* ---------- Motto block ---------- */
.page-about .about-motto {
  position: relative;
  overflow: hidden;
  background: var(--paper-50);
  border-radius: var(--radius-panel);
  padding: clamp(26px, 5vw, 52px) clamp(20px, 4.4vw, 46px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.28);
}

.page-about .about-motto::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(115deg, rgba(14, 116, 144, 0.12) 0 1px, transparent 1px 15px);
  pointer-events: none;
}

.page-about .about-motto__zh {
  position: relative;
  margin: 0;
  font-size: clamp(1.5rem, 5.6vw, 2.85rem);
  font-weight: 200;
  line-height: 1.22;
  letter-spacing: -0.015em;
  color: var(--ink-950);
  max-width: 20ch;
}

.page-about .about-motto__en {
  position: relative;
  margin: 16px 0 0;
  font-family: var(--font-narrow);
  text-transform: uppercase;
  letter-spacing: 0.16em;
  font-size: clamp(11px, 2.6vw, 13.5px);
  color: var(--cyan-700);
}

/* ---------- Phase timeline ---------- */
.page-about .about-phases {
  margin-top: 6px;
  border-top: 1px solid var(--about-line);
}

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

.page-about .about-phase summary {
  list-style: none;
  cursor: pointer;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px 14px;
  padding: 17px 0;
  transition: color 0.18s var(--ease);
}

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

.page-about .about-phase summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 16px;
  line-height: 1;
  color: var(--signal-500);
}

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

.page-about .about-phase__num {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  color: var(--cyan-400);
}

.page-about .about-phase__name {
  font-size: 17px;
  font-weight: 500;
  color: var(--text-900);
}

.page-about .about-phase summary em {
  font-style: normal;
  font-size: 13px;
  line-height: 1.6;
  color: var(--text-300);
}

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

.page-about .about-phase__body p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.85;
  color: var(--text-300);
  max-width: 68ch;
}

/* ---------- Note grid ---------- */
.page-about .about-notes {
  list-style: none;
  margin: 4px 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .about-note {
  min-width: 0;
  padding: 20px 20px 18px;
  background: var(--ink-850);
  border: 1px solid var(--about-line);
  border-radius: var(--radius-soft);
  transition: border-color 0.2s var(--ease);
}

.page-about .about-note:hover {
  border-color: var(--cyan-400);
}

.page-about .about-note__num {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--cyan-400);
  font-variant-numeric: tabular-nums;
}

.page-about .about-note h3 {
  margin: 9px 0 8px;
  font-size: 17.5px;
  font-weight: 500;
  line-height: 1.4;
  color: var(--text-900);
}

.page-about .about-note p {
  margin: 0;
  font-size: 15px;
  line-height: 1.82;
  color: var(--text-300);
  max-width: none;
}

/* ---------- Steps ---------- */
.page-about .about-steps {
  list-style: none;
  margin: 4px 0 0;
  padding: 0;
}

.page-about .about-step {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  gap: 16px;
  padding: 20px 0;
  border-top: 1px solid var(--about-line);
}

.page-about .about-step:last-child {
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-step__num {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.06em;
  color: var(--signal-500);
  padding-top: 4px;
}

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

.page-about .about-step__body h3 {
  margin: 0 0 8px;
  font-size: 17px;
  font-weight: 500;
  line-height: 1.4;
  color: var(--text-900);
}

.page-about .about-step__body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-300);
  max-width: 64ch;
}

/* ---------- Status list ---------- */
.page-about .about-status {
  list-style: none;
  margin: 4px 0 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: 1px solid var(--about-line);
}

.page-about .about-status li {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 14px;
  padding: 15px 0;
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-status__note {
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--text-300);
}

/* ---------- Links ---------- */
.page-about .about-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 15px;
  color: var(--cyan-400);
  text-decoration: none;
  padding-bottom: 2px;
  border-bottom: 1px solid rgba(34, 211, 238, 0.35);
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.page-about .about-link::after {
  content: "→";
  font-family: var(--font-mono);
  font-size: 14px;
}

.page-about .about-link:hover {
  color: var(--ember-400);
  border-color: var(--ember-400);
}

/* ---------- Close ---------- */
.page-about .about-close {
  border-top: 1px solid var(--about-line);
  padding-top: 38px;
  padding-bottom: 88px;
}

.page-about .about-close__eyebrow {
  margin: 0;
  font-family: var(--font-narrow);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--text-300);
}

.page-about .about-close__line {
  margin: 14px 0 0;
  font-size: clamp(1.15rem, 3.4vw, 1.6rem);
  font-weight: 300;
  line-height: 1.5;
  color: var(--text-900);
  max-width: 26ch;
}

.page-about .about-close__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 14px;
  margin-top: 24px;
}

.page-about .about-close__link {
  display: inline-flex;
  align-items: center;
  padding: 11px 20px;
  border: 1px solid var(--about-line);
  border-radius: var(--radius-pill);
  font-size: 14.5px;
  color: var(--text-300);
  text-decoration: none;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease), background-color 0.18s var(--ease);
}

.page-about .about-close__link:hover {
  color: var(--text-900);
  border-color: var(--signal-500);
  background: rgba(255, 90, 31, 0.08);
}

/* ---------- Tablet ---------- */
@media (min-width: 700px) {
  .page-about .about-notes {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-hero {
    padding-top: 32px;
  }
}

/* ---------- Desktop ---------- */
@media (min-width: 960px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 1.04fr) minmax(0, 0.96fr);
    align-items: center;
    gap: 56px;
    padding-top: 44px;
    padding-bottom: 104px;
  }

  .page-about .about-hero__lead {
    font-size: 17px;
  }

  .page-about .about-chapter__body {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: 24px 44px;
  }

  .page-about .about-chapter__body > .about-span-all {
    grid-column: 1 / -1;
  }

  .page-about .about-chapter {
    padding-top: 42px;
    margin-bottom: 88px;
  }

  .page-about .about-chapter__head {
    gap: 8px 22px;
    margin-bottom: 30px;
  }
}

@media (min-width: 1024px) {
  .page-about .about-shell {
    grid-template-columns: var(--about-axis-w) minmax(0, 1fr);
    gap: 56px;
    padding-bottom: 104px;
  }

  .page-about .about-index {
    position: sticky;
    top: calc(var(--header-h) + 28px);
  }

  .page-about .about-index__list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    padding: 4px 0 0;
    margin-top: 16px;
  }

  .page-about .about-index__list li {
    flex: 0 1 auto;
  }

  .page-about .about-index__link {
    border: 0;
    border-left: 1px solid var(--about-line);
    border-radius: 0;
    padding: 10px 0 10px 16px;
    white-space: normal;
    font-size: 14px;
    line-height: 1.5;
  }

  .page-about .about-index__link:hover {
    border-left-color: var(--signal-500);
    color: var(--text-900);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-note,
  .page-about .about-index__link,
  .page-about .about-close__link,
  .page-about .about-link,
  .page-about .about-phase summary {
    transition-duration: 0.12s;
  }
}
</main>