.page-about {
  --ab-line: rgba(var(--silver-rgb), .16);
  --ab-line-strong: rgba(var(--silver-rgb), .3);
  --ab-sticky-top: 6.5rem;
  background: var(--ink);
  color: var(--light);
  font-family: var(--font-body);
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  position: relative;
  isolation: isolate;
  padding-top: clamp(.75rem, 2vw, 1.25rem);
  padding-bottom: clamp(2.5rem, 5vw, 4rem);
}

.page-about .ab-hero::before {
  content: "";
  position: absolute;
  z-index: -1;
  top: 0;
  right: 0;
  width: min(62%, 760px);
  height: 68%;
  background: linear-gradient(150deg, rgba(var(--night-rgb), .32), rgba(var(--flame-rgb), .12) 58%, transparent 88%);
  clip-path: polygon(16% 0, 100% 0, 100% 100%, 0 76%);
  pointer-events: none;
}

.page-about .ab-hero__grid {
  display: grid;
  gap: clamp(1.5rem, 3.5vw, 2.75rem);
  margin-top: clamp(1.25rem, 3vw, 2rem);
  align-items: center;
}

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

.page-about .ab-hero__title {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(2.1rem, 5.6vw, 4.1rem);
  line-height: 1.04;
  letter-spacing: -.022em;
  margin: .5rem 0 1rem;
  text-wrap: balance;
}

.page-about .ab-hero__lede {
  margin: 0;
  max-width: 36em;
  font-size: clamp(1rem, .55vw + .85rem, 1.1rem);
  line-height: 1.85;
  color: rgba(var(--light-rgb), .8);
}

.page-about .ab-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
  margin-top: clamp(1.25rem, 3vw, 1.85rem);
}

.page-about .ab-hero__figure {
  position: relative;
  margin: 0;
  background: var(--stand);
  border: var(--edge);
  overflow: hidden;
  clip-path: polygon(0 0, 100% 0, 100% 88%, 10% 100%);
}

.page-about .ab-hero__figure::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--flame), var(--night));
}

.page-about .ab-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  filter: saturate(.88) contrast(1.04);
}

/* ---------- 关键数字 ---------- */
.page-about .ab-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.25rem clamp(1rem, 3vw, 2.25rem);
  list-style: none;
  margin: clamp(2rem, 4vw, 3rem) 0 0;
  padding: clamp(1.25rem, 3vw, 1.85rem) 0 0;
  border-top: var(--edge-strong);
}

.page-about .ab-stat {
  position: relative;
  padding-left: .95rem;
  min-width: 0;
}

.page-about .ab-stat::before {
  content: "";
  position: absolute;
  left: 0;
  top: .35rem;
  width: 3px;
  height: calc(100% - .6rem);
  background: linear-gradient(to bottom, var(--flame), rgba(var(--flame-rgb), 0));
}

.page-about .ab-stat__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.3rem, 2.4vw, 1.8rem);
  line-height: 1;
  letter-spacing: .01em;
  color: var(--light);
}

.page-about .ab-stat__label {
  margin: .55rem 0 0;
  font-size: .875rem;
  line-height: 1.6;
  color: var(--silver);
}

/* ---------- 时间轴骨架 ---------- */
.page-about .ab-timeline {
  padding: clamp(2rem, 4.5vw, 3.25rem) 0 clamp(1.5rem, 4vw, 2.5rem);
  border-top: 1px solid rgba(var(--silver-rgb), .1);
}

.page-about .ab-timeline__head {
  display: grid;
  gap: 1rem;
  margin-bottom: clamp(1.25rem, 3vw, 2rem);
}

.page-about .ab-timeline__title {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(1.6rem, 3.4vw, 2.55rem);
  line-height: 1.1;
  letter-spacing: -.015em;
  margin: .35rem 0 0;
}

.page-about .ab-timeline__note {
  margin: 0;
  font-family: var(--font-serif);
  font-size: clamp(.95rem, .4vw + .85rem, 1.05rem);
  line-height: 1.85;
  color: rgba(var(--light-rgb), .74);
}

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

.page-about .ab-step {
  display: grid;
  gap: clamp(.9rem, 2.5vw, 1.5rem);
  padding: clamp(1.6rem, 3.5vw, 2.6rem) 0;
  border-top: var(--edge);
}

.page-about .ab-step:last-child {
  border-bottom: var(--edge);
}

.page-about .ab-step__rail {
  display: flex;
  align-items: baseline;
  gap: .85rem;
  min-width: 0;
}

.page-about .ab-step__rail::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 0;
  height: 0;
}

.page-about .ab-step__num {
  font-family: var(--font-mono);
  font-size: clamp(1.75rem, 3.6vw, 2.7rem);
  line-height: .9;
  letter-spacing: -.02em;
  color: var(--flame);
}

.page-about .ab-step__phase {
  font-family: var(--font-mono);
  font-size: .75rem;
  letter-spacing: .16em;
  color: var(--silver);
  white-space: nowrap;
}

.page-about .ab-step__body {
  min-width: 0;
  max-width: 44rem;
}

.page-about .ab-step__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.35rem, 2.4vw, 1.95rem);
  line-height: 1.2;
  letter-spacing: -.01em;
  margin: 0 0 .75rem;
}

.page-about .ab-step__body p {
  margin: 0 0 1rem;
  line-height: 1.85;
  color: rgba(var(--light-rgb), .82);
}

.page-about .ab-step__body p:last-child {
  margin-bottom: 0;
}

.page-about .ab-step__body a:not(.btn) {
  color: var(--linkblue);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.page-about .ab-step__body a:not(.btn):hover {
  color: var(--light);
}

.page-about .ab-step__body .ab-step__cue {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .5rem;
  margin: 1.15rem 0 0;
  padding: .65rem .9rem;
  border-left: 3px solid var(--flame);
  background: rgba(var(--stand-rgb), .72);
  font-family: var(--font-mono);
  font-size: .8125rem;
  line-height: 1.6;
  color: var(--silver);
}

/* ---------- 版本标签页 ---------- */
.page-about .ab-tabs {
  margin: 1.25rem 0 0;
}

.page-about .ab-tabs__list {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  padding-bottom: .75rem;
  border-bottom: var(--edge);
}

.page-about .ab-tab {
  appearance: none;
  -webkit-appearance: none;
  cursor: pointer;
  border: 1px solid rgba(var(--silver-rgb), .28);
  background: transparent;
  color: var(--silver);
  font-family: var(--font-body);
  font-size: .9375rem;
  font-weight: 700;
  line-height: 1.2;
  padding: .55rem 1.2rem;
  border-radius: var(--pill);
  transition: background-color .16s var(--ease), color .16s var(--ease), border-color .16s var(--ease);
}

.page-about .ab-tab:hover {
  color: var(--light);
  border-color: rgba(var(--silver-rgb), .55);
}

.page-about .ab-tab[aria-selected="true"] {
  background: var(--flame);
  border-color: var(--flame);
  color: var(--ink);
}

.page-about .ab-tab[aria-selected="true"]:hover {
  color: var(--ink);
}

.page-about .ab-tab:focus-visible {
  outline: 2px solid var(--linkblue);
  outline-offset: 3px;
}

.page-about .ab-tabpanel {
  padding-top: 1.15rem;
}

.page-about .ab-tabpanel:focus-visible {
  outline: 2px solid var(--linkblue);
  outline-offset: 4px;
}

.page-about .ab-tabpanel p {
  margin: 0 0 .85rem;
  line-height: 1.85;
  color: rgba(var(--light-rgb), .82);
}

.page-about .ab-tabpanel ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: .55rem;
}

.page-about .ab-tabpanel li {
  position: relative;
  padding-left: 1.15rem;
  font-size: .9375rem;
  line-height: 1.75;
  color: rgba(var(--light-rgb), .8);
}

.page-about .ab-tabpanel li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .62em;
  width: 7px;
  height: 7px;
  background: var(--night);
  transform: rotate(45deg);
}

/* ---------- 图块 ---------- */
.page-about .ab-figure {
  position: relative;
  margin: 1.5rem 0 0;
  background: var(--stand);
  border: var(--edge);
  overflow: hidden;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 18px), 0 100%);
}

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

.page-about .ab-figure--wide img {
  aspect-ratio: 4 / 3;
}

.page-about .ab-figure--square {
  max-width: 26rem;
}

.page-about .ab-figure--square img {
  aspect-ratio: 1 / 1;
}

.page-about .ab-figure figcaption {
  padding: .7rem .9rem;
  font-size: .8125rem;
  line-height: 1.6;
  color: var(--silver);
  background: rgba(var(--stand-rgb), .85);
  border-top: var(--edge);
}

/* ---------- 纸白节奏面板 ---------- */
.page-about .ab-step--paper .ab-step__body {
  background: var(--paper);
  color: var(--ink);
  padding: clamp(1.15rem, 3vw, 2rem);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 20px), 0 100%);
}

.page-about .ab-step--paper .ab-step__title {
  color: var(--ink);
}

.page-about .ab-step--paper .ab-step__body p {
  color: rgba(var(--ink-rgb), .84);
}

.page-about .ab-pulse {
  list-style: none;
  margin: 1.25rem 0;
  padding: 0;
  display: grid;
  gap: .5rem;
}

.page-about .ab-pulse li {
  display: grid;
  gap: .15rem;
  padding: .7rem .85rem;
  background: rgba(var(--ink-rgb), .055);
  border-left: 3px solid var(--flame);
}

.page-about .ab-pulse__time {
  font-family: var(--font-mono);
  font-size: .8125rem;
  font-weight: 700;
  letter-spacing: .02em;
  color: var(--concrete);
}

.page-about .ab-pulse__text {
  font-size: .9375rem;
  line-height: 1.65;
  color: rgba(var(--ink-rgb), .84);
}

/* ---------- 团队手风琴 ---------- */
.page-about .ab-team {
  display: grid;
  gap: .6rem;
  margin: 1.25rem 0;
}

.page-about .ab-team details {
  background: rgba(var(--stand-rgb), .72);
  border: var(--edge);
  border-left: 3px solid rgba(var(--flame-rgb), .8);
  padding: 0 1rem;
}

.page-about .ab-team summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: .9rem 0;
  cursor: pointer;
  list-style: none;
  font-weight: 700;
  font-size: .9375rem;
  line-height: 1.4;
  color: var(--light);
}

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

.page-about .ab-team summary::after {
  content: "+";
  flex: none;
  font-family: var(--font-mono);
  font-size: 1.15rem;
  line-height: 1;
  color: var(--flame);
}

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

.page-about .ab-team summary:focus-visible {
  outline: 2px solid var(--linkblue);
  outline-offset: 2px;
}

.page-about .ab-team details p {
  margin: 0 0 .95rem;
  font-size: .9375rem;
  line-height: 1.8;
  color: rgba(var(--light-rgb), .78);
}

/* ---------- 页尾入口 ---------- */
.page-about .ab-next {
  position: relative;
  margin-top: clamp(1.5rem, 4vw, 2.5rem);
  padding: clamp(2.25rem, 5vw, 3.5rem) 0 clamp(2.5rem, 5vw, 4rem);
  background: linear-gradient(120deg, rgba(var(--night-rgb), .24), transparent 58%), var(--stand);
  border-top: 1px solid rgba(var(--flame-rgb), .45);
  clip-path: polygon(0 3.5%, 100% 0, 100% 100%, 0 100%);
  overflow: hidden;
}

.page-about .ab-next::after {
  content: "";
  position: absolute;
  right: -8%;
  bottom: -30%;
  width: 34%;
  aspect-ratio: 1 / 1;
  border: 1px solid rgba(var(--flame-rgb), .3);
  border-radius: 50%;
  pointer-events: none;
}

.page-about .ab-next__inner {
  display: grid;
  gap: 1.5rem;
  position: relative;
  z-index: 1;
}

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

.page-about .ab-next__title {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(1.5rem, 3.2vw, 2.4rem);
  line-height: 1.12;
  letter-spacing: -.015em;
  margin: .35rem 0 .75rem;
}

.page-about .ab-next__lede {
  margin: 0;
  max-width: 40em;
  font-size: .975rem;
  line-height: 1.85;
  color: rgba(var(--light-rgb), .8);
}

.page-about .ab-next__actions {
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
  align-content: start;
}

/* ---------- 响应式 ---------- */
@media (min-width: 620px) {
  .page-about .ab-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .ab-pulse li {
    grid-template-columns: 9.5rem minmax(0, 1fr);
    align-items: baseline;
    gap: 1rem;
  }
}

@media (min-width: 880px) {
  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 1.02fr) minmax(0, .98fr);
  }

  .page-about .ab-timeline__head {
    grid-template-columns: minmax(0, .95fr) minmax(0, 1.05fr);
    align-items: end;
    gap: clamp(2rem, 5vw, 4rem);
  }

  .page-about .ab-step {
    grid-template-columns: minmax(150px, 210px) minmax(0, 1fr);
    gap: clamp(1.75rem, 4.5vw, 4rem);
  }

  .page-about .ab-step__rail {
    position: sticky;
    top: var(--ab-sticky-top);
    align-self: start;
    flex-direction: column;
    align-items: flex-start;
    gap: .6rem;
    padding-top: .35rem;
  }

  .page-about .ab-step__rail::before {
    width: 1px;
    height: 1.6rem;
    top: auto;
    bottom: -.4rem;
    left: .55rem;
    background: linear-gradient(to bottom, rgba(var(--flame-rgb), .55), rgba(var(--silver-rgb), .06));
  }

  .page-about .ab-next__inner {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, .9fr);
    align-items: center;
    gap: clamp(2rem, 5vw, 4rem);
  }

  .page-about .ab-next__actions {
    justify-content: flex-end;
  }
}

@media (max-width: 560px) {
  .page-about .ab-hero__figure {
    clip-path: polygon(0 0, 100% 0, 100% 93%, 6% 100%);
  }

  .page-about .ab-next__actions .btn {
    flex: 1 1 100%;
    text-align: center;
  }

  .page-about .ab-step--paper .ab-step__body {
    clip-path: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-tab {
    transition: none;
  }
}