.page-about {
  --ab-rail: 176px;
  --ab-gap: clamp(16px, 2.4vw, 28px);
  background:
    radial-gradient(1000px 520px at 78% -6%, rgba(79, 179, 199, .10), transparent 62%),
    radial-gradient(760px 420px at 8% 8%, rgba(216, 52, 47, .10), transparent 66%),
    var(--d28-night);
  color: var(--d28-text);
  overflow-x: clip;
}

.page-about a:focus-visible,
.page-about summary:focus-visible {
  outline: 2px solid var(--d28-cyan);
  outline-offset: 2px;
}

.page-about .d28-h2 { margin: 0 0 16px; }
.page-about .d28-h3 { margin: 0 0 12px; }
.page-about .d28-h4 { margin: 0 0 8px; }
.page-about .d28-text {
  margin: 0 0 16px;
  color: rgba(233, 238, 247, .82);
  line-height: 1.75;
}
.page-about .d28-text:last-child { margin-bottom: 0; }

/* ---------- 首屏拼贴 ---------- */
.page-about .ab-hero {
  padding: clamp(32px, 5.6vw, 72px) 0 clamp(48px, 7vw, 96px);
}
.page-about .ab-hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 34px;
}
.page-about .ab-hero h1 { margin: 14px 0 0; }
.page-about .ab-hero .d28-lede { margin-top: 20px; }
.page-about .ab-hero__links { margin-top: 28px; }

.page-about .ab-mosaic {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}
.page-about .ab-mosaic__cell {
  display: flex;
  flex-direction: column;
  gap: 8px;
  min-width: 0;
  padding: 16px 18px;
  border: 1px solid var(--d28-line);
  border-radius: var(--d28-r-md);
  background: linear-gradient(160deg, rgba(19, 30, 51, .96), rgba(11, 20, 36, .96));
}
.page-about .ab-mosaic__cell--lead {
  grid-column: span 2;
  border-left: 3px solid var(--d28-red);
  border-radius: 4px var(--d28-r-md) var(--d28-r-md) 4px;
}
.page-about .ab-mosaic__cell--wide { grid-column: span 2; }
.page-about .ab-mosaic__k {
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--d28-muted);
}
.page-about .ab-mosaic__v {
  font-family: var(--d28-mono);
  font-size: clamp(30px, 5vw, 46px);
  font-weight: 700;
  line-height: 1.05;
  color: var(--d28-text);
}
.page-about .ab-mosaic__v--sm {
  font-family: var(--d28-sans);
  font-size: 16px;
  font-weight: 600;
  line-height: 1.6;
}

/* ---------- 纵向长卷章节 ---------- */
.page-about .ab-chapter {
  position: relative;
  padding: clamp(50px, 7vw, 100px) 0;
}
.page-about .ab-chapter + .ab-chapter { border-top: 1px solid rgba(36, 50, 77, .7); }
.page-about .ab-chapter--close { padding-bottom: clamp(64px, 8vw, 120px); }

.page-about .ab-chapter__inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 22px;
}
.page-about .ab-chapter__body { min-width: 0; }

.page-about .ab-plate {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin: 0;
  padding-left: 14px;
  border-left: 2px solid var(--d28-gold);
}
.page-about .ab-plate__k {
  font-size: 15px;
  font-weight: 800;
  letter-spacing: .04em;
  color: var(--d28-text);
}
.page-about .ab-plate__v {
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--d28-muted);
}

/* ---------- 图像 ---------- */
.page-about .ab-figure {
  margin: 26px 0;
  border: 1px solid var(--d28-line);
  border-radius: var(--d28-r-lg);
  overflow: hidden;
  background: linear-gradient(150deg, rgba(19, 30, 51, .9), rgba(5, 7, 12, .9));
}
.page-about .ab-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
}
.page-about .ab-figure__cap {
  padding: 12px 18px 14px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--d28-muted);
  border-top: 1px solid rgba(36, 50, 77, .7);
}

/* ---------- 折叠注解 ---------- */
.page-about .ab-note {
  margin-top: 22px;
  border: 1px solid var(--d28-line);
  border-radius: var(--d28-r-md);
  background: rgba(19, 30, 51, .6);
  overflow: hidden;
}
.page-about .ab-note > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 18px;
  font-size: 15px;
  font-weight: 700;
  color: var(--d28-text);
  cursor: pointer;
  list-style: none;
}
.page-about .ab-note > summary::-webkit-details-marker { display: none; }
.page-about .ab-note > summary::after {
  content: "展开";
  flex: none;
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--d28-gold);
}
.page-about .ab-note[open] > summary::after { content: "收起"; }
.page-about .ab-note__body {
  padding: 0 18px 18px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--d28-muted);
}
.page-about .ab-note__body p { margin: 0; }

/* ---------- 三原则 ---------- */
.page-about .ab-principles {
  display: grid;
  gap: 12px;
  margin-top: 24px;
}
.page-about .ab-principle {
  border: 1px solid var(--d28-line);
  border-radius: var(--d28-r-md);
  background: linear-gradient(140deg, rgba(19, 30, 51, .92), rgba(11, 20, 36, .92));
  overflow: hidden;
  transition: border-color .2s var(--d28-ease);
}
.page-about .ab-principle[open] { border-color: rgba(200, 150, 62, .55); }
.page-about .ab-principle > summary {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
}
.page-about .ab-principle > summary::-webkit-details-marker { display: none; }
.page-about .ab-principle > summary::after {
  content: "+";
  flex: none;
  font-family: var(--d28-mono);
  font-size: 18px;
  color: var(--d28-cyan);
}
.page-about .ab-principle[open] > summary::after {
  content: "−";
  color: var(--d28-gold);
}
.page-about .ab-principle__idx {
  flex: none;
  font-family: var(--d28-mono);
  font-size: 13px;
  color: var(--d28-gold);
}
.page-about .ab-principle__name {
  flex: 1;
  min-width: 0;
  font-size: 17px;
  font-weight: 800;
  color: var(--d28-text);
}
.page-about .ab-principle__body {
  padding: 0 18px 18px 18px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--d28-muted);
}
.page-about .ab-principle__body p { margin: 0; }

/* ---------- 三步流程 ---------- */
.page-about .ab-flow {
  display: grid;
  gap: 14px;
  margin-top: 24px;
}
.page-about .ab-flow__node {
  position: relative;
  min-width: 0;
  padding: 18px;
  border: 1px solid var(--d28-line);
  border-radius: var(--d28-r-md);
  background: rgba(19, 30, 51, .55);
}
.page-about .ab-flow__node .d28-text { font-size: 15px; }
.page-about .ab-flow__node::after {
  content: "";
  position: absolute;
  left: 26px;
  bottom: -14px;
  width: 1px;
  height: 14px;
  background: linear-gradient(var(--d28-gold), transparent);
}
.page-about .ab-flow__node:last-child::after { display: none; }
.page-about .ab-flow__idx {
  display: block;
  margin-bottom: 10px;
  font-family: var(--d28-mono);
  font-size: 22px;
  font-weight: 700;
  color: var(--d28-red);
}

/* ---------- 横向主题带 ---------- */
.page-about .ab-band {
  margin: clamp(40px, 5vw, 72px) 0;
  padding: 22px 0;
  border-top: 1px solid var(--d28-line);
  border-bottom: 1px solid var(--d28-line);
  background: linear-gradient(90deg, rgba(122, 27, 28, .34), rgba(11, 20, 36, 0) 64%);
}
.page-about .ab-band--quiet {
  background: linear-gradient(90deg, rgba(79, 179, 199, .16), rgba(11, 20, 36, 0) 64%);
}
.page-about .ab-band__row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px 20px;
}
.page-about .ab-band__text {
  flex: 1 1 300px;
  min-width: 0;
  margin: 0;
  font-size: 16px;
  line-height: 1.7;
  color: var(--d28-text);
}
.page-about .ab-band__link {
  flex: none;
  font-size: 14px;
  font-weight: 700;
  color: var(--d28-gold);
  text-decoration: none;
  border-bottom: 1px solid rgba(200, 150, 62, .4);
  padding-bottom: 2px;
}
.page-about .ab-band__link:hover,
.page-about .ab-band__link:focus-visible {
  color: var(--d28-text);
  border-bottom-color: var(--d28-red);
}

/* ---------- 规模数字 ---------- */
.page-about .ab-scale {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 24px 0 22px;
  border: 1px solid var(--d28-line);
  border-radius: var(--d28-r-lg);
  background: var(--d28-line);
  overflow: hidden;
}
.page-about .ab-scale__item {
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-width: 0;
  padding: 20px 18px;
  background: var(--d28-ink);
}
.page-about .ab-scale__v {
  font-family: var(--d28-mono);
  font-size: clamp(26px, 4.4vw, 40px);
  font-weight: 700;
  line-height: 1;
  color: var(--d28-text);
}
.page-about .ab-scale__item:nth-child(4) .ab-scale__v { color: var(--d28-gold); }
.page-about .ab-scale__k {
  font-size: 13px;
  line-height: 1.6;
  color: var(--d28-muted);
}

/* ---------- 校准清单 ---------- */
.page-about .ab-check {
  list-style: none;
  margin: 20px 0;
  padding: 0;
  display: grid;
  gap: 10px;
}
.page-about .ab-check li {
  position: relative;
  padding: 12px 16px 12px 40px;
  border: 1px solid rgba(36, 50, 77, .85);
  border-radius: var(--d28-r-sm);
  background: rgba(19, 30, 51, .5);
  font-size: 15px;
  line-height: 1.7;
  color: rgba(233, 238, 247, .84);
}
.page-about .ab-check li::before {
  content: "";
  position: absolute;
  left: 16px;
  top: 20px;
  width: 8px;
  height: 8px;
  border-radius: 2px;
  background: var(--d28-cyan);
}
.page-about .ab-check li:nth-child(4)::before { background: var(--d28-gold); }
.page-about .ab-links { margin-top: 20px; }

/* ---------- 里程碑带 ---------- */
.page-about .ab-miles {
  display: grid;
  gap: 0;
  margin: 30px 0 8px;
}
.page-about .ab-mile {
  position: relative;
  min-width: 0;
  padding: 18px 16px 18px 22px;
  border-left: 1px solid var(--d28-line);
}
.page-about .ab-mile::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 24px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--d28-line);
}
.page-about .ab-mile__y {
  display: block;
  margin-bottom: 6px;
  font-family: var(--d28-mono);
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--d28-cyan);
}
.page-about .ab-mile p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--d28-muted);
}
.page-about .ab-mile--gold::before { background: var(--d28-gold); }
.page-about .ab-mile--gold .ab-mile__y { color: var(--d28-gold); }
.page-about .ab-mile--now::before {
  background: var(--d28-red);
  box-shadow: 0 0 0 4px rgba(216, 52, 47, .16);
}
.page-about .ab-mile--now .ab-mile__y { color: var(--d28-red); }

/* ---------- 结语引用与内链 ---------- */
.page-about .ab-quote {
  margin: 0;
  padding: clamp(24px, 3.4vw, 40px) clamp(22px, 3.4vw, 44px);
  border: 1px solid var(--d28-line);
  border-left: 3px solid var(--d28-red);
  border-radius: var(--d28-r-lg);
  background:
    linear-gradient(150deg, rgba(19, 30, 51, .95), rgba(5, 7, 12, .95)),
    repeating-linear-gradient(0deg, rgba(36, 50, 77, .45) 0 1px, transparent 1px 24px);
}
.page-about .ab-quote p {
  margin: 0;
  font-size: clamp(17px, 2.2vw, 22px);
  font-weight: 700;
  line-height: 1.7;
  letter-spacing: .01em;
  color: var(--d28-text);
}
.page-about .ab-quote__by {
  margin-top: 16px;
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--d28-gold);
}

.page-about .ab-next {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  margin-top: 30px;
}
.page-about .ab-next__item {
  display: flex;
  flex-direction: column;
  gap: 8px;
  min-width: 0;
  padding: 18px;
  border: 1px solid var(--d28-line);
  border-radius: var(--d28-r-md);
  background: rgba(19, 30, 51, .55);
  color: inherit;
  text-decoration: none;
  transition: border-color .2s var(--d28-ease), background-color .2s var(--d28-ease), transform .2s var(--d28-ease);
}
.page-about .ab-next__item:hover,
.page-about .ab-next__item:focus-visible {
  border-color: rgba(216, 52, 47, .7);
  background: rgba(19, 30, 51, .92);
  transform: translateY(-2px);
}
.page-about .ab-next__k {
  font-size: 15px;
  font-weight: 800;
  color: var(--d28-text);
}
.page-about .ab-next__t {
  font-size: 13px;
  line-height: 1.65;
  color: var(--d28-muted);
}

/* ---------- 断点 ---------- */
@media (min-width: 700px) {
  .page-about .ab-next { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .page-about .ab-scale { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

@media (min-width: 760px) {
  .page-about .ab-principles { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .page-about .ab-principle__body { padding-left: 18px; }
  .page-about .ab-flow { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
  .page-about .ab-flow__node::after {
    left: auto;
    right: -16px;
    bottom: auto;
    top: 34px;
    width: 16px;
    height: 1px;
    background: linear-gradient(90deg, var(--d28-gold), transparent);
  }
}

@media (min-width: 860px) {
  .page-about .ab-miles { grid-template-columns: repeat(5, minmax(0, 1fr)); }
  .page-about .ab-mile {
    padding: 20px 14px 18px;
    border-left: none;
    border-top: 1px solid var(--d28-line);
  }
  .page-about .ab-mile::before { left: 14px; top: -5px; }
  .page-about .ab-mile:nth-child(1) { padding-top: 74px; }
  .page-about .ab-mile:nth-child(2) { padding-top: 56px; }
  .page-about .ab-mile:nth-child(3) { padding-top: 42px; }
  .page-about .ab-mile:nth-child(4) { padding-top: 64px; }
  .page-about .ab-mile:nth-child(5) { padding-top: 32px; }
}

@media (min-width: 900px) {
  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 1.12fr) minmax(0, .88fr);
    gap: 56px;
    align-items: end;
  }
  .page-about .ab-mosaic__cell--offset { margin-top: 20px; }
  .page-about .ab-chapter__inner {
    grid-template-columns: var(--ab-rail) minmax(0, 1fr);
    gap: 48px;
    align-items: start;
  }
}

@media (min-width: 1040px) {
  .page-about .ab-next { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-principle,
  .page-about .ab-next__item { transition: none; }
  .page-about .ab-next__item:hover,
  .page-about .ab-next__item:focus-visible { transform: none; }
}