.page-about {
  display: block;
  position: relative;
  color: var(--paper);
  background:
    linear-gradient(180deg, var(--ink) 0%, var(--ink-3) 42%, #04070d 100%);
}

.page-about a {
  color: inherit;
}

.page-about .breadcrumb {
  padding-top: clamp(14px, 2.4vw, 22px);
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  position: relative;
  overflow: hidden;
  padding: clamp(26px, 5vw, 54px) 0 clamp(30px, 6vw, 76px);
}

.page-about .ab-hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 58px 58px;
  opacity: 0.42;
  -webkit-mask-image: linear-gradient(to bottom, #000 0%, transparent 88%);
  mask-image: linear-gradient(to bottom, #000 0%, transparent 88%);
  pointer-events: none;
}

.page-about .ab-hero::before {
  content: "";
  position: absolute;
  top: -18%;
  right: -12%;
  width: min(640px, 78%);
  height: 132%;
  background: linear-gradient(158deg, rgba(30, 107, 255, 0.34) 0%, rgba(34, 211, 238, 0.12) 48%, rgba(7, 11, 20, 0) 76%);
  clip-path: polygon(26% 0, 100% 0, 100% 100%, 0 74%);
  pointer-events: none;
}

.page-about .ab-hero__inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(24px, 4vw, 46px);
  align-items: center;
}

.page-about .ab-hero__copy h1 {
  margin: 10px 0 16px;
  max-width: 20ch;
}

.page-about .ab-hero__copy .lead {
  max-width: 58ch;
}

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

.page-about .ab-status {
  border: 1px solid var(--line);
  border-left: 2px solid var(--cyan);
  background: linear-gradient(158deg, rgba(14, 22, 38, 0.96), rgba(7, 11, 20, 0.92));
  padding: 16px 18px 12px;
  box-shadow: var(--shadow-island);
}

.page-about .ab-status__head {
  margin: 0 0 6px;
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--rock);
}

.page-about .ab-status__row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  padding: 11px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .ab-status__row:last-child {
  border-bottom: 0;
}

.page-about .ab-status__k {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: var(--rock);
}

.page-about .ab-status__v {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--paper);
  text-align: right;
}

.page-about .ab-status__v--neon {
  color: var(--neon);
}

/* ---------- 品牌 ---------- */
.page-about .ab-brand__grid {
  display: grid;
  gap: clamp(18px, 3vw, 34px);
}

.page-about .ab-brand__head h2 {
  margin-top: 10px;
  max-width: 16ch;
}

.page-about .ab-brand__body p {
  margin: 0 0 16px;
}

.page-about .ab-brand__body p:last-of-type {
  margin-bottom: 20px;
}

.page-about .ab-brand__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

/* ---------- 图框 ---------- */
.page-about .ab-frame {
  position: relative;
  margin: clamp(26px, 5vw, 46px) 0 clamp(24px, 4vw, 40px);
  border: 1px solid var(--line);
  background: linear-gradient(150deg, rgba(30, 107, 255, 0.14), rgba(7, 11, 20, 0.94) 58%, rgba(34, 211, 238, 0.1));
  overflow: hidden;
}

.page-about .ab-frame::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 40px 40px;
  opacity: 0.4;
  pointer-events: none;
}

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

.page-about .ab-frame__cap {
  position: relative;
  display: block;
  padding: 9px 14px;
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--rock);
  border-top: 1px solid var(--line-soft);
  background: rgba(7, 11, 20, 0.72);
}

.page-about .ab-frame--moss {
  background: linear-gradient(150deg, rgba(111, 138, 94, 0.22), rgba(7, 11, 20, 0.94) 62%);
  border-color: rgba(111, 138, 94, 0.5);
  margin: 20px 0 22px;
}

.page-about .ab-frame--net {
  margin: 0;
  background: linear-gradient(150deg, rgba(34, 211, 238, 0.16), rgba(7, 11, 20, 0.94) 60%);
}

/* ---------- 时间轴 ---------- */
.page-about .ab-tl__lead {
  max-width: 62ch;
  margin: 14px 0 30px;
}

.page-about .ab-tl__list {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}

.page-about .ab-tl__list::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 10px;
  width: 1px;
  background: linear-gradient(180deg, var(--clay) 0%, var(--line-strong) 40%, rgba(30, 107, 255, 0.6) 78%, var(--neon) 100%);
}

.page-about .ab-tl__item {
  position: relative;
  padding: 0 0 28px 34px;
}

.page-about .ab-tl__node {
  position: absolute;
  left: 0;
  top: 7px;
  width: 15px;
  height: 15px;
  background: var(--ink);
  border: 1px solid var(--clay);
  transform: rotate(45deg);
}

.page-about .ab-tl__item--current .ab-tl__node {
  border-color: var(--neon);
  background: rgba(74, 222, 128, 0.16);
  box-shadow: 0 0 0 4px rgba(74, 222, 128, 0.08);
}

.page-about .ab-tl__ver {
  margin: 0 0 6px;
  font-size: 12.5px;
  letter-spacing: 0.1em;
  color: var(--clay);
}

.page-about .ab-tl__item--current .ab-tl__ver {
  color: var(--neon);
}

.page-about .ab-tl__body h3 {
  margin: 0 0 8px;
}

.page-about .ab-tl__body p {
  margin: 0;
  max-width: 68ch;
}

.page-about .ab-tl__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 14px;
}

.page-about .ab-tl__note {
  margin: 10px 0 0;
  padding: 14px 16px;
  border-left: 2px solid var(--cyan);
  background: rgba(14, 22, 38, 0.7);
  color: var(--rock);
  font-size: 14px;
}

.page-about .ab-tl__note a {
  color: var(--cyan);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---------- 中段两块 ---------- */
.page-about .ab-split {
  display: grid;
  gap: clamp(20px, 3.4vw, 34px);
  margin-top: clamp(30px, 6vw, 62px);
}

.page-about .ab-block {
  border: 1px solid var(--line);
  border-top: 2px solid var(--blue);
  background: linear-gradient(168deg, rgba(14, 22, 38, 0.9), rgba(7, 11, 20, 0.72));
  padding: clamp(20px, 3vw, 32px);
}

.page-about .ab-block--moss {
  border-top-color: var(--moss);
}

.page-about .ab-block h2 {
  margin: 10px 0 14px;
}

.page-about .ab-block p {
  margin: 0 0 16px;
}

.page-about .ab-block p a {
  color: var(--cyan);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* 环形图 */
.page-about .ab-donut-wrap {
  display: grid;
  gap: 18px;
  align-items: center;
  margin: 22px 0 24px;
  padding: 18px 0;
  border-top: 1px solid var(--line-soft);
  border-bottom: 1px solid var(--line-soft);
}

.page-about .ab-donut {
  width: min(190px, 62%);
  height: auto;
  margin: 0 auto;
}

.page-about .ab-donut__seg {
  transition: stroke-width 0.22s var(--ease), opacity 0.22s var(--ease);
}

.page-about .ab-donut__seg:hover {
  stroke-width: 19;
}

.page-about .ab-donut__num {
  font-family: var(--font-mono);
  font-size: 22px;
  fill: var(--paper);
}

.page-about .ab-donut__unit {
  font-family: var(--font-mono);
  font-size: 9px;
  letter-spacing: 0.12em;
  fill: var(--rock);
}

.page-about .ab-legend {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .ab-legend__item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .ab-legend__item:last-child {
  border-bottom: 0;
}

.page-about .ab-legend__dot {
  width: 8px;
  height: 8px;
  flex: none;
}

.page-about .ab-legend__dot--a {
  background: var(--blue);
}

.page-about .ab-legend__dot--b {
  background: var(--clay);
}

.page-about .ab-legend__dot--c {
  background: var(--cyan);
}

.page-about .ab-legend__name {
  flex: 1 1 auto;
  font-size: 14px;
  color: var(--paper);
}

.page-about .ab-legend__num {
  font-size: 13px;
  color: var(--paper);
}

/* ---------- 基础设施 ---------- */
.page-about .ab-infra__grid {
  display: grid;
  gap: clamp(20px, 3.4vw, 34px);
  align-items: start;
}

.page-about .ab-infra__body h2 {
  margin: 10px 0 14px;
}

.page-about .ab-infra__body p {
  margin: 0 0 16px;
}

.page-about .ab-infra__list {
  display: grid;
  gap: 0;
  margin: 22px 0 0;
  border-top: 1px solid var(--line);
}

.page-about .ab-infra__item {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .ab-infra__item dt {
  font-size: 11.5px;
  letter-spacing: 0.08em;
  color: var(--rock);
}

.page-about .ab-infra__item dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 13.5px;
  color: var(--paper);
}

/* ---------- 信息带 ---------- */
.page-about .ab-band {
  margin-top: clamp(34px, 6vw, 66px);
  border: 1px solid var(--line);
  background: linear-gradient(120deg, var(--ink-2) 0%, rgba(7, 11, 20, 0.96) 62%, rgba(30, 107, 255, 0.14) 100%);
  padding: clamp(20px, 3.4vw, 36px);
}

.page-about .ab-band h2 {
  margin: 10px 0 10px;
}

.page-about .ab-band__lead {
  margin: 0 0 22px;
  color: var(--rock);
  max-width: 60ch;
}

.page-about .ab-band__grid {
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .ab-band__cell {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 14px;
  padding: 14px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .ab-band__k {
  min-width: 88px;
  font-size: 11.5px;
  letter-spacing: 0.08em;
  color: var(--rock);
}

.page-about .ab-band__v {
  color: var(--paper);
  font-size: 14.5px;
  word-break: break-word;
}

.page-about .ab-band__hint {
  flex: 1 1 100%;
  font-size: 13px;
  color: var(--rock);
}

.page-about .ab-band .copy-btn {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  padding: 5px 11px;
  border: 1px solid var(--line-strong);
  background: rgba(34, 211, 238, 0.08);
  color: var(--cyan);
  border-radius: var(--radius);
  cursor: pointer;
}

.page-about .ab-band .copy-btn:hover {
  border-color: var(--cyan);
}

.page-about .ab-band .copy-btn.is-copied {
  color: var(--neon);
  border-color: rgba(74, 222, 128, 0.6);
  background: rgba(74, 222, 128, 0.1);
}

/* ---------- 下一步 ---------- */
.page-about .ab-next__list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .ab-next__item a {
  display: grid;
  grid-template-columns: 42px 1fr;
  grid-template-rows: auto auto;
  column-gap: 14px;
  padding: 16px 18px;
  border: 1px solid var(--line);
  background: rgba(14, 22, 38, 0.6);
  text-decoration: none;
  transition: border-color 0.22s var(--ease), transform 0.22s var(--ease);
}

.page-about .ab-next__item a:hover,
.page-about .ab-next__item a:focus-visible {
  border-color: var(--blue);
  transform: translateY(-2px);
}

.page-about .ab-next__idx {
  grid-row: 1 / span 2;
  font-size: 12px;
  color: var(--cyan);
  letter-spacing: 0.08em;
}

.page-about .ab-next__t {
  font-weight: 700;
  font-size: 16px;
  color: var(--paper);
}

.page-about .ab-next__d {
  margin-top: 4px;
  font-size: 13.5px;
  line-height: 1.6;
  color: var(--rock);
}

/* ---------- 响应式 ---------- */
@media (min-width: 700px) {
  .page-about .ab-hero__inner {
    grid-template-columns: 1.5fr 0.9fr;
  }

  .page-about .ab-donut-wrap {
    grid-template-columns: auto 1fr;
  }

  .page-about .ab-band__grid {
    grid-template-columns: 1fr 1fr;
  }

  .page-about .ab-band__cell {
    border-bottom: 1px solid var(--line-soft);
    padding-right: 20px;
  }

  .page-about .ab-band__cell--wide {
    grid-column: 1 / -1;
  }
}

@media (min-width: 900px) {
  .page-about .ab-brand__grid {
    grid-template-columns: 0.85fr 1.15fr;
    gap: clamp(24px, 4vw, 52px);
    align-items: start;
  }

  .page-about .ab-infra__grid {
    grid-template-columns: 1.1fr 0.9fr;
  }

  .page-about .ab-tl__item {
    display: grid;
    grid-template-columns: 96px 1fr;
    column-gap: 26px;
    padding-left: 38px;
  }

  .page-about .ab-tl__ver {
    margin: 4px 0 0;
    text-align: right;
  }

  .page-about .ab-tl__body {
    border-left: 1px solid var(--line-soft);
    padding-left: 26px;
  }

  .page-about .ab-next__list {
    grid-template-columns: 1fr 1fr;
    gap: 14px;
  }
}

@media (min-width: 1060px) {
  .page-about .ab-split {
    grid-template-columns: 1.04fr 0.96fr;
    align-items: start;
  }
}

@media (max-width: 699px) {
  .page-about .ab-hero::before {
    top: auto;
    bottom: -20%;
    right: -30%;
    width: 120%;
    height: 76%;
    clip-path: polygon(0 34%, 100% 0, 100% 100%, 0 100%);
  }

  .page-about .ab-hero__copy h1 {
    max-width: none;
  }

  .page-about .ab-band__k {
    min-width: 72px;
  }

  .page-about .ab-next__item a {
    grid-template-columns: 34px 1fr;
  }
}

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