.page-about {
  --ab-pad: clamp(18px, 4vw, 44px);
  --ab-gap: clamp(16px, 2.4vw, 32px);
  --ab-hair: 1px solid rgba(168, 183, 199, 0.16);
  --ab-hair-strong: 1px solid rgba(168, 183, 199, 0.28);
  background:
    radial-gradient(1100px 560px at 90% -8%, rgba(25, 245, 198, 0.10), transparent 62%),
    radial-gradient(820px 480px at -6% 18%, rgba(255, 90, 42, 0.11), transparent 64%),
    var(--ink-950);
  color: var(--paper-50);
  padding-bottom: clamp(32px, 5vw, 72px);
}

.page-about h1,
.page-about h2,
.page-about h3 {
  font-family: var(--font-head);
  letter-spacing: -0.01em;
}

.page-about .ab-crumb {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(16px, 2.4vw, 26px) var(--ab-pad) 0;
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--slate-300);
}

.page-about .ab-crumb a {
  color: var(--slate-300);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) ease, border-color var(--dur) ease;
}

.page-about .ab-crumb a:hover,
.page-about .ab-crumb a:focus-visible {
  color: var(--cyan-400);
  border-bottom-color: var(--cyan-400);
}

.page-about .cx-ball--sm {
  --size: 26px;
}

/* ---------- hero ---------- */
.page-about .ab-hero {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(22px, 4vw, 52px) var(--ab-pad) clamp(30px, 5vw, 62px);
}

.page-about .ab-hero__inner {
  display: grid;
  gap: var(--ab-gap);
  min-width: 0;
}

.page-about .ab-hero__body {
  min-width: 0;
}

.page-about .ab-hero__mark {
  display: flex;
  align-items: center;
  gap: 16px;
}

.page-about .ab-vertical {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.26em;
  color: var(--cyan-400);
  padding-left: 10px;
  border-left: 1px solid rgba(25, 245, 198, 0.4);
  line-height: 1.2;
}

.page-about .ab-balls {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.page-about .ab-hero__title {
  margin: 12px 0 0;
  max-width: 16em;
}

.page-about .ab-hero__lede {
  margin-top: 18px;
  max-width: 60ch;
  color: var(--slate-300);
}

.page-about .ab-facts {
  margin-top: clamp(22px, 3vw, 32px);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(132px, 1fr));
  gap: 12px;
}

.page-about .ab-fact {
  border: var(--ab-hair);
  border-radius: var(--r-sm);
  background: linear-gradient(160deg, rgba(12, 32, 56, 0.85), rgba(7, 20, 38, 0.6));
  padding: 14px 16px;
}

.page-about .ab-fact__k {
  display: block;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--slate-300);
}

.page-about .ab-fact__v {
  display: block;
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: clamp(20px, 2.6vw, 27px);
  letter-spacing: 0.02em;
  color: var(--cyan-400);
}

.page-about .ab-hero__actions {
  margin-top: clamp(22px, 3vw, 32px);
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- section nav ---------- */
.page-about .ab-toc {
  position: sticky;
  top: var(--topbar);
  z-index: 6;
  background: rgba(5, 13, 26, 0.9);
  backdrop-filter: blur(10px);
  border-top: var(--ab-hair);
  border-bottom: var(--ab-hair);
}

.page-about .ab-toc__inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 11px var(--ab-pad);
  display: flex;
  align-items: center;
  gap: 10px;
  overflow-x: auto;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}

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

.page-about .ab-toc__label {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.22em;
  color: var(--gold-500);
  padding-right: 4px;
  border-right: 1px solid rgba(244, 196, 94, 0.4);
}

.page-about .ab-toc a {
  flex: 0 0 auto;
  padding: 6px 15px;
  border-radius: var(--pill);
  border: var(--ab-hair-strong);
  color: var(--slate-300);
  text-decoration: none;
  font-size: 13px;
  white-space: nowrap;
  transition: color var(--dur) ease, background var(--dur) ease, border-color var(--dur) ease;
}

.page-about .ab-toc a:hover,
.page-about .ab-toc a:focus-visible {
  color: var(--ink-950);
  background: var(--cyan-400);
  border-color: var(--cyan-400);
}

/* ---------- generic section ---------- */
.page-about .ab-section {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(40px, 6vw, 84px) var(--ab-pad);
}

.page-about .ab-split {
  display: grid;
  gap: clamp(20px, 3vw, 44px);
  min-width: 0;
}

.page-about .ab-split__lead,
.page-about .ab-split__main {
  min-width: 0;
}

.page-about .ab-split__note {
  margin-top: 16px;
  max-width: 42ch;
  color: var(--slate-300);
  font-size: 15px;
  line-height: 1.8;
}

.page-about .ab-vertical--side {
  display: none;
  margin-top: 26px;
  color: var(--gold-500);
  border-left-color: rgba(244, 196, 94, 0.4);
}

/* ---------- figures ---------- */
.page-about .ab-figure {
  margin: 0;
  border-radius: var(--r-md);
  overflow: hidden;
  border: var(--ab-hair);
  background: var(--ink-800);
  box-shadow: var(--shadow-soft);
}

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

/* ---------- timeline ---------- */
.page-about .ab-steps {
  list-style: none;
  margin: var(--ab-gap) 0 0;
  padding: 0;
  position: relative;
}

.page-about .ab-steps::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 10px;
  bottom: 10px;
  width: 2px;
  border-radius: 2px;
  background: linear-gradient(180deg, var(--orange-500), var(--gold-500) 48%, var(--cyan-400));
}

.page-about .ab-step {
  position: relative;
  padding-left: 30px;
  margin-bottom: 12px;
  min-width: 0;
}

.page-about .ab-step__node {
  position: absolute;
  left: 0;
  top: 17px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--ink-950);
  border: 2px solid var(--gold-500);
  box-shadow: 0 0 0 5px rgba(244, 196, 94, 0.1);
}

.page-about .ab-step__box {
  border: var(--ab-hair);
  border-radius: var(--r-sm);
  background: linear-gradient(160deg, rgba(12, 32, 56, 0.9), rgba(7, 20, 38, 0.7));
  padding: 13px 16px;
  transition: border-color var(--dur) ease, background var(--dur) ease;
}

.page-about .ab-step__box[open] {
  border-color: rgba(25, 245, 198, 0.42);
}

.page-about .ab-step__box summary {
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: baseline;
  gap: 12px;
  flex-wrap: wrap;
}

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

.page-about .ab-step__box summary::after {
  content: "展开";
  margin-left: auto;
  font-size: 12px;
  font-weight: 400;
  letter-spacing: 0.08em;
  color: var(--slate-300);
}

.page-about .ab-step__box[open] summary::after {
  content: "收起";
  color: var(--cyan-400);
}

.page-about .ab-step__year {
  font-family: var(--font-mono);
  font-size: 15px;
  letter-spacing: 0.06em;
  color: var(--gold-500);
}

.page-about .ab-step__name {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 16px;
}

.page-about .ab-step__box p {
  margin: 12px 0 0;
  color: var(--slate-300);
  font-size: 15px;
  line-height: 1.78;
}

/* ---------- review ---------- */
.page-about .ab-review__head {
  max-width: 62ch;
}

.page-about .ab-review__lede {
  margin-top: 16px;
  color: var(--slate-300);
}

.page-about .ab-review__grid {
  margin-top: clamp(24px, 3.5vw, 42px);
  display: grid;
  gap: clamp(18px, 2.6vw, 32px);
  min-width: 0;
}

.page-about .ab-flow {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .ab-flow__item {
  position: relative;
  border: var(--ab-hair);
  border-radius: var(--r-md);
  background: rgba(12, 32, 56, 0.62);
  padding: 18px 20px 18px 24px;
}

.page-about .ab-flow__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 18px;
  bottom: 18px;
  width: 3px;
  border-radius: 3px;
  background: var(--cyan-400);
}

.page-about .ab-flow__item:nth-child(2)::before {
  background: var(--gold-500);
}

.page-about .ab-flow__item:nth-child(3)::before {
  background: var(--orange-500);
}

.page-about .ab-flow__idx {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--gold-500);
}

.page-about .ab-flow__item h3 {
  margin: 6px 0 8px;
  font-size: 19px;
}

.page-about .ab-flow__item p {
  margin: 0 0 12px;
  color: var(--slate-300);
  font-size: 15px;
  line-height: 1.78;
}

/* ---------- team ---------- */
.page-about .ab-group {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .ab-group__item {
  border: var(--ab-hair);
  border-radius: var(--r-md);
  background: linear-gradient(150deg, rgba(22, 50, 79, 0.62), rgba(7, 20, 38, 0.55));
  padding: 18px 20px;
}

.page-about .ab-group__item p {
  margin: 12px 0 0;
  color: var(--slate-300);
  font-size: 15px;
  line-height: 1.78;
}

/* ---------- region band ---------- */
.page-about .ab-band {
  display: grid;
  gap: clamp(18px, 2.6vw, 34px);
  border-radius: var(--r-lg);
  border: var(--ab-hair-strong);
  padding: clamp(22px, 3.2vw, 42px);
  background:
    linear-gradient(135deg, rgba(25, 245, 198, 0.12), transparent 46%),
    var(--ink-800);
  overflow: hidden;
}

.page-about .ab-band__text {
  min-width: 0;
}

.page-about .ab-band__text p {
  margin-top: 16px;
  color: var(--slate-300);
  font-size: 15px;
  line-height: 1.8;
  max-width: 56ch;
}

.page-about .ab-band__list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.page-about .ab-band__list li {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border-radius: var(--pill);
  border: 1px solid rgba(244, 196, 94, 0.35);
  background: rgba(5, 13, 26, 0.55);
  font-size: 13px;
  color: var(--slate-300);
}

.page-about .ab-band__list .cx-num {
  font-family: var(--font-mono);
  color: var(--gold-500);
  letter-spacing: 0.04em;
}

.page-about .ab-band__fig {
  min-width: 0;
  align-self: stretch;
}

/* ---------- principles ---------- */
.page-about .ab-principles__head {
  max-width: 62ch;
}

.page-about .ab-principles__head .cx-lede {
  margin-top: 16px;
  color: var(--slate-300);
}

.page-about .ab-principles__list {
  list-style: none;
  margin: clamp(24px, 3.4vw, 42px) 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .ab-principle {
  border-radius: var(--r-md);
  padding: 22px 22px 24px;
  background: var(--paper-50);
  color: var(--ink-950);
  border: 1px solid rgba(5, 13, 26, 0.08);
}

.page-about .ab-principle:nth-child(even) {
  background: transparent;
  color: var(--paper-50);
  border: var(--ab-hair-strong);
}

.page-about .ab-principle__num {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.24em;
  color: var(--orange-500);
}

.page-about .ab-principle h3 {
  margin: 8px 0 10px;
  font-size: clamp(20px, 2.4vw, 24px);
}

.page-about .ab-principle p {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  opacity: 0.84;
}

/* ---------- cta ---------- */
.page-about .ab-cta {
  padding-top: 0;
}

.page-about .ab-cta__inner {
  display: grid;
  gap: clamp(18px, 2.6vw, 34px);
  border-radius: var(--r-lg);
  border: var(--ab-hair-strong);
  padding: clamp(24px, 3.4vw, 46px);
  background:
    radial-gradient(620px 260px at 8% 0%, rgba(255, 90, 42, 0.18), transparent 72%),
    var(--ink-800);
}

.page-about .ab-cta__text {
  min-width: 0;
}

.page-about .ab-cta__text p {
  margin-top: 16px;
  color: var(--slate-300);
  font-size: 15px;
  line-height: 1.8;
  max-width: 58ch;
}

.page-about .ab-cta__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-content: start;
}

.page-about .ab-cta__links a {
  display: inline-flex;
  align-items: center;
  padding: 10px 18px;
  border-radius: var(--pill);
  border: var(--ab-hair-strong);
  color: var(--paper-50);
  text-decoration: none;
  font-size: 14px;
  transition: background var(--dur) ease, border-color var(--dur) ease, color var(--dur) ease;
}

.page-about .ab-cta__links a:hover,
.page-about .ab-cta__links a:focus-visible {
  background: var(--orange-500);
  border-color: var(--orange-500);
  color: var(--paper-50);
}

/* ---------- to top ---------- */
.page-about .ab-totop-wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--ab-pad) clamp(20px, 3vw, 36px);
  display: flex;
  justify-content: center;
}

.page-about .ab-totop {
  text-decoration: none;
}

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

  .page-about .ab-principle:nth-child(even) {
    transform: translateY(18px);
  }

  .page-about .ab-principles__list {
    padding-bottom: 18px;
  }
}

@media (min-width: 900px) {
  .page-about .ab-hero__inner {
    grid-template-columns: 96px minmax(0, 1fr);
    align-items: stretch;
    gap: clamp(20px, 2.6vw, 36px);
  }

  .page-about .ab-hero__mark {
    flex-direction: column;
    align-items: flex-start;
    justify-content: space-between;
    padding-top: 6px;
  }

  .page-about .ab-vertical {
    writing-mode: vertical-rl;
    text-orientation: mixed;
    min-height: 190px;
  }

  .page-about .ab-vertical--side {
    display: block;
    min-height: 220px;
  }

  .page-about .ab-toc__inner {
    justify-content: flex-start;
  }
}

@media (min-width: 960px) {
  .page-about .ab-split {
    grid-template-columns: minmax(0, 0.82fr) minmax(0, 1.18fr);
    align-items: start;
  }

  .page-about .ab-split--flip {
    grid-template-columns: minmax(0, 1.18fr) minmax(0, 0.82fr);
  }

  .page-about .ab-split--flip .ab-split__lead {
    order: 2;
  }

  .page-about .ab-split--flip .ab-split__main {
    order: 1;
  }

  .page-about .ab-review__grid {
    grid-template-columns: minmax(0, 0.92fr) minmax(0, 1.08fr);
    align-items: start;
  }

  .page-about .ab-flow {
    gap: 18px;
  }

  .page-about .ab-flow__item:nth-child(2) {
    margin-left: clamp(14px, 2vw, 26px);
  }

  .page-about .ab-flow__item:nth-child(3) {
    margin-left: clamp(7px, 1vw, 13px);
  }

  .page-about .cx-band.ab-band {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    align-items: center;
  }

  .page-about .ab-cta__inner {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    align-items: center;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-toc a,
  .page-about .ab-cta__links a,
  .page-about .ab-crumb a,
  .page-about .ab-step__box {
    transition: none;
  }

  .page-about .ab-principle:nth-child(even) {
    transform: none;
  }
}
<<<END>>>