.page-about {
  background: var(--night);
  color: var(--white);
  font-family: var(--font-sans);
  overflow-x: clip;
}

/* ---------- 首屏：对角错位色块 ---------- */
.page-about .about-hero {
  position: relative;
  background: var(--night);
  padding: 28px 0 clamp(40px, 7vw, 76px);
  overflow: hidden;
  isolation: isolate;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: -30% -10% -30% 34%;
  background: var(--dark-green);
  clip-path: polygon(22% 0, 100% 0, 100% 100%, 0 100%);
  z-index: -2;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(180deg, rgba(11, 32, 24, .92) 0%, rgba(11, 32, 24, .55) 60%, rgba(11, 32, 24, .95) 100%),
    repeating-linear-gradient(135deg, rgba(247, 250, 248, .04) 0 1px, transparent 1px 9px);
  z-index: -1;
  pointer-events: none;
}

.page-about .about-hero__inner {
  position: relative;
}

.page-about .about-hero .breadcrumbs {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  letter-spacing: .06em;
  color: var(--mist);
  margin-bottom: clamp(22px, 4vw, 40px);
}

.page-about .about-hero .breadcrumbs a {
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--speed) var(--ease), border-color var(--speed) var(--ease);
}

.page-about .about-hero .breadcrumbs a:hover {
  color: var(--lime);
  border-bottom-color: var(--lime);
}

.page-about .about-hero .breadcrumbs__sep {
  color: rgba(154, 168, 161, .55);
}

.page-about .about-hero__tag {
  display: inline-block;
  margin: 0 0 14px;
  font-size: 12px;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--lime);
  border: 1px solid rgba(200, 255, 61, .4);
  padding: 5px 10px;
  background: rgba(200, 255, 61, .06);
}

.page-about .about-hero__title {
  margin: 0 0 20px;
  font-size: clamp(30px, 7.2vw, 62px);
  line-height: 1.08;
  font-weight: 800;
  letter-spacing: -.02em;
  color: var(--white);
  max-width: 18ch;
}

.page-about .about-hero__lede {
  margin: 0;
  max-width: 40ch;
  font-size: clamp(16px, 2.2vw, 18px);
  line-height: 1.78;
  color: rgba(247, 250, 248, .82);
}

.page-about .about-hero__cut {
  position: absolute;
  right: 0;
  bottom: -1px;
  width: clamp(120px, 30vw, 320px);
  height: 4px;
  background: var(--lime);
  clip-path: polygon(0 0, 100% 0, 100% 100%, 0 100%);
  transform: skewX(-38deg);
  transform-origin: left bottom;
}

/* ---------- 主题簇索引 ---------- */
.page-about .about-index .section-head {
  margin-bottom: clamp(20px, 3.4vw, 36px);
}

.page-about .about-index__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-index__list li {
  background: var(--charcoal);
}

.page-about .about-index__list a {
  display: grid;
  grid-template-columns: auto 1fr;
  grid-template-areas:
    "num title"
    "num desc";
  column-gap: 16px;
  align-items: center;
  padding: 16px 18px;
  text-decoration: none;
  color: var(--white);
  transition: background var(--speed) var(--ease);
}

.page-about .about-index__list a:hover,
.page-about .about-index__list a:focus-visible {
  background: var(--dark-green);
}

.page-about .about-index__num {
  grid-area: num;
  font-family: var(--font-num);
  font-size: 26px;
  font-weight: 900;
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--lime);
  min-width: 42px;
}

.page-about .about-index__title {
  grid-area: title;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: .01em;
}

.page-about .about-index__desc {
  grid-area: desc;
  font-size: 13px;
  line-height: 1.6;
  color: var(--mist);
}

@media (min-width: 760px) {
  .page-about .about-index__list {
    grid-template-columns: 1fr 1fr;
  }
}

/* ---------- 双栏外壳：章节轨道 + 正文 ---------- */
.page-about .about-shell {
  background: var(--night);
  padding-bottom: clamp(28px, 5vw, 64px);
}

.page-about .about-shell__inner {
  display: block;
}

.page-about .chapter-rail {
  position: sticky;
  top: 0;
  z-index: 6;
  margin: 0 0 18px;
  padding: 10px 0 12px;
  background: rgba(11, 32, 24, .94);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}

.page-about .chapter-rail__title {
  display: none;
  margin: 0 0 12px;
  font-size: 11px;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--mist);
}

.page-about .chapter-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 4px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}

.page-about .chapter-rail__list::-webkit-scrollbar {
  display: none;
}

.page-about .chapter-rail__link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  white-space: nowrap;
  padding: 7px 12px;
  font-size: 13px;
  line-height: 1.2;
  color: rgba(247, 250, 248, .8);
  text-decoration: none;
  border: 1px solid var(--line);
  background: rgba(20, 53, 39, .5);
  transition: color var(--speed) var(--ease), border-color var(--speed) var(--ease), background var(--speed) var(--ease);
}

.page-about .chapter-rail__tick {
  width: 12px;
  height: 2px;
  background: rgba(154, 168, 161, .6);
  flex: none;
  transition: background var(--speed) var(--ease), width var(--speed) var(--ease);
}

.page-about .chapter-rail__link:hover,
.page-about .chapter-rail__link:focus-visible {
  color: var(--lime);
  border-color: rgba(200, 255, 61, .55);
  background: rgba(200, 255, 61, .08);
}

.page-about .chapter-rail__link:hover .chapter-rail__tick,
.page-about .chapter-rail__link:focus-visible .chapter-rail__tick {
  background: var(--lime);
  width: 20px;
}

.page-about .chapter-rail__back {
  display: none;
  margin-top: 16px;
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid rgba(154, 168, 161, .35);
  align-self: flex-start;
}

.page-about .chapter-rail__back:hover {
  color: var(--lime);
  border-bottom-color: var(--lime);
}

@media (min-width: 1080px) {
  .page-about .about-shell__inner {
    display: grid;
    grid-template-columns: 176px minmax(0, 1fr);
    gap: clamp(32px, 4vw, 64px);
    align-items: start;
  }

  .page-about .chapter-rail {
    position: sticky;
    top: calc(var(--topbar-h) + 24px);
    margin: 0;
    padding: 0 0 0 14px;
    background: transparent;
    backdrop-filter: none;
    border-bottom: none;
    border-left: 2px solid var(--line);
  }

  .page-about .chapter-rail__title {
    display: block;
  }

  .page-about .chapter-rail__list {
    display: block;
    overflow: visible;
    padding: 0;
  }

  .page-about .chapter-rail__list li + li {
    margin-top: 2px;
  }

  .page-about .chapter-rail__link {
    display: flex;
    width: 100%;
    padding: 9px 0 9px 2px;
    font-size: 13.5px;
    line-height: 1.45;
    border: none;
    background: none;
    white-space: normal;
    position: relative;
  }

  .page-about .chapter-rail__link::before {
    content: "";
    position: absolute;
    left: -16px;
    top: 50%;
    width: 12px;
    height: 2px;
    background: var(--line-strong);
    transform: translateY(-50%);
    transition: background var(--speed) var(--ease), width var(--speed) var(--ease);
  }

  .page-about .chapter-rail__link:hover::before,
  .page-about .chapter-rail__link:focus-visible::before {
    background: var(--lime);
    width: 20px;
  }

  .page-about .chapter-rail__tick {
    display: none;
  }

  .page-about .chapter-rail__back {
    display: inline-block;
  }
}

/* ---------- 章节通用 ---------- */
.page-about .about-body {
  display: block;
}

.page-about .about-ch {
  position: relative;
  padding: clamp(34px, 6vw, 66px) 0 clamp(30px, 5vw, 58px);
  border-top: 1px solid var(--line);
}

.page-about .about-ch:first-child {
  border-top: none;
  padding-top: clamp(22px, 4vw, 40px);
}

.page-about .about-ch__head {
  margin-bottom: clamp(20px, 3.4vw, 34px);
}

.page-about .about-ch__num {
  margin: 0 0 10px;
  font-family: var(--font-num);
  font-size: 13px;
  font-weight: 900;
  letter-spacing: .22em;
  color: var(--lime);
}

.page-about .about-ch__title {
  margin: 0;
  font-size: clamp(23px, 4.4vw, 38px);
  line-height: 1.18;
  font-weight: 800;
  letter-spacing: -.015em;
  color: var(--white);
  max-width: 22ch;
}

.page-about .about-ch__lede {
  margin: 14px 0 0;
  max-width: 38ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

.page-about .about-prose p {
  margin: 0 0 18px;
  max-width: 38ch;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(247, 250, 248, .86);
}

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

/* ---------- 01 起点 ---------- */
.page-about .about-ch__body--split {
  display: block;
}

.page-about .origin-figure {
  margin: 26px 0 0;
}

.page-about .origin-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--line-strong);
  filter: saturate(.65) contrast(1.05);
}

.page-about .origin-figure figcaption {
  margin-top: 10px;
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--mist);
  border-left: 2px solid var(--lime);
  padding-left: 10px;
}

@media (min-width: 880px) {
  .page-about .about-ch__body--split {
    display: grid;
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .85fr);
    gap: clamp(28px, 4vw, 56px);
    align-items: start;
  }

  .page-about .origin-figure {
    margin: -18px 0 0;
  }
}

/* ---------- 02 原则（暖纸 + 战术板） ---------- */
.page-about .about-ch--paper {
  background: var(--paper);
  color: var(--ink);
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  padding-left: clamp(18px, 3.4vw, 40px);
  padding-right: clamp(18px, 3.4vw, 40px);
  margin: clamp(18px, 3vw, 30px) 0;
}

.page-about .about-ch--paper::after {
  content: "";
  position: absolute;
  left: 8px;
  right: 8px;
  bottom: -6px;
  height: 6px;
  background: var(--paper);
  border: 1px solid var(--rule);
  border-top: none;
  opacity: .5;
  pointer-events: none;
}

.page-about .about-ch--paper .about-ch__num {
  color: var(--score);
}

.page-about .about-ch--paper .about-ch__title {
  color: var(--ink);
  text-shadow: 0 1px 0 rgba(27, 30, 28, .16);
}

.page-about .about-ch--paper .about-ch__lede {
  color: rgba(27, 30, 28, .68);
}

.page-about .about-ch--board {
  overflow: hidden;
  isolation: isolate;
}

.page-about .board-img {
  position: absolute;
  inset: 0;
  z-index: -1;
  opacity: .16;
  mix-blend-mode: multiply;
  pointer-events: none;
}

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

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

.page-about .principle {
  position: relative;
  background: rgba(247, 250, 248, .72);
  border: 1px solid var(--rule);
  padding: 18px 18px 20px 18px;
  display: grid;
  gap: 10px;
}

.page-about .principle__seal {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  font-family: var(--font-num);
  font-size: 22px;
  font-weight: 900;
  letter-spacing: -.02em;
  color: var(--paper);
  background: var(--ink);
  border: 2px solid var(--ink);
  box-shadow: 3px 3px 0 0 var(--score);
  transition: transform 240ms var(--ease), box-shadow 240ms var(--ease);
}

.page-about .principle:hover .principle__seal,
.page-about .principle:focus-within .principle__seal {
  transform: translateY(-5px);
  box-shadow: 3px 8px 0 0 var(--score);
}

.page-about .principle__title {
  margin: 0;
  font-size: 18px;
  font-weight: 800;
  letter-spacing: -.01em;
  color: var(--ink);
}

.page-about .principle__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: rgba(27, 30, 28, .78);
  max-width: 42ch;
}

@media (min-width: 900px) {
  .page-about .principle-list {
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
  }

  .page-about .principle:nth-child(2) {
    transform: translateY(14px);
  }

  .page-about .principle:nth-child(3) {
    transform: translateY(28px);
  }

  .page-about .about-ch--board {
    padding-bottom: clamp(56px, 7vw, 90px);
  }
}

/* ---------- 03 版本阶梯 ---------- */
.page-about .about-ch--wide {
  padding-top: 0;
}

.page-about .version-banner {
  margin: 0 0 clamp(22px, 3.4vw, 38px);
  border: 1px solid var(--line-strong);
  position: relative;
}

.page-about .version-banner img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  filter: saturate(.7) contrast(1.08);
}

.page-about .version-banner::after {
  content: "";
  position: absolute;
  inset: auto 0 0 0;
  height: 52%;
  background: linear-gradient(180deg, transparent, rgba(11, 32, 24, .88));
  pointer-events: none;
}

.page-about .version-ladder {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .version__panel {
  height: 100%;
  background: var(--dark-green);
  border: 1px solid var(--line-strong);
  display: flex;
  flex-direction: column;
}

.page-about .version__head {
  list-style: none;
  cursor: pointer;
  padding: 16px 16px 14px;
  display: grid;
  gap: 6px;
}

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

.page-about .version__head::marker {
  content: "";
}

.page-about .version__num {
  font-family: var(--font-num);
  font-size: 30px;
  font-weight: 900;
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--score);
}

.page-about .version__name {
  font-size: 15px;
  font-weight: 700;
  color: var(--white);
  letter-spacing: .01em;
}

.page-about .version__cue {
  font-size: 11.5px;
  letter-spacing: .12em;
  color: var(--mist);
  border-top: 1px solid var(--line);
  padding-top: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.page-about .version__cue::before {
  content: "";
  width: 9px;
  height: 2px;
  background: var(--lime);
  flex: none;
  transition: width var(--speed) var(--ease);
}

.page-about .version__panel[open] .version__cue::before {
  width: 18px;
}

.page-about .version__panel[open] .version__cue {
  color: var(--lime);
}

.page-about .version__body {
  padding: 0 16px 18px;
  animation: about-slip 240ms var(--ease) both;
}

.page-about .version__body p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.78;
  color: rgba(247, 250, 248, .8);
}

@keyframes about-slip {
  from {
    opacity: 0;
    transform: translateY(-6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (min-width: 760px) {
  .page-about .version-ladder {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 14px;
    align-items: stretch;
  }

  .page-about .version:nth-child(1) .version__panel { margin-top: 96px; }
  .page-about .version:nth-child(2) .version__panel { margin-top: 64px; }
  .page-about .version:nth-child(3) .version__panel { margin-top: 32px; }
  .page-about .version:nth-child(4) .version__panel { margin-top: 0; }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .version__body {
    animation: none;
  }
}

/* ---------- 04 团队 ---------- */
.page-about .team-grid {
  display: grid;
  gap: 16px;
}

.page-about .team-card {
  background: var(--dark-green);
  border: 1px solid var(--line-strong);
  padding: 20px 20px 22px;
  position: relative;
}

.page-about .team-card::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 4px;
  height: 100%;
  background: var(--lime);
}

.page-about .team-card:nth-child(2)::before {
  background: var(--score);
}

.page-about .team-card__count {
  margin: 0 0 6px;
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--mist);
}

.page-about .team-card__count span {
  font-family: var(--font-num);
  font-size: 40px;
  font-weight: 900;
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--score);
  margin-right: 6px;
  vertical-align: -6px;
}

.page-about .team-card__head {
  margin: 0 0 14px;
  font-size: 19px;
  font-weight: 800;
  color: var(--white);
}

.page-about .team-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .team-list li {
  position: relative;
  padding-left: 16px;
  font-size: 14.5px;
  line-height: 1.72;
  color: rgba(247, 250, 248, .78);
}

.page-about .team-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .72em;
  width: 7px;
  height: 2px;
  background: var(--lime);
}

@media (min-width: 820px) {
  .page-about .team-grid {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, .85fr);
    gap: 20px;
  }
}

.page-about .shift-band {
  margin-top: clamp(26px, 4vw, 44px);
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .shift {
  background: var(--charcoal);
  padding: 16px 18px;
}

.page-about .shift__time {
  margin: 0 0 6px;
  font-family: var(--font-num);
  font-size: 14px;
  font-weight: 900;
  letter-spacing: .1em;
  color: var(--lime);
}

.page-about .shift__desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.68;
  color: rgba(247, 250, 248, .74);
}

@media (min-width: 760px) {
  .page-about .shift-band {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* ---------- 05 社群 ---------- */
.page-about .about-ch--paper .about-prose p {
  color: rgba(27, 30, 28, .82);
  max-width: 40ch;
}

.page-about .city-grid {
  margin-top: clamp(20px, 3vw, 32px);
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.page-about .city-chip {
  display: inline-block;
  padding: 6px 13px;
  font-size: 13.5px;
  letter-spacing: .04em;
  color: var(--ink);
  background: rgba(247, 250, 248, .6);
  border: 1px solid var(--rule);
  transition: background var(--speed) var(--ease), color var(--speed) var(--ease), border-color var(--speed) var(--ease);
}

.page-about .city-chip:nth-child(4n + 1) {
  background: rgba(255, 90, 43, .12);
  border-color: rgba(255, 90, 43, .38);
}

.page-about .city-chip:hover {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink);
}

/* ---------- 06 接下来 ---------- */
.page-about .next-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 18px;
}

.page-about .next-item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-areas:
    "idx title"
    "idx desc";
  column-gap: 16px;
  align-items: start;
  padding-bottom: 18px;
  border-bottom: 1px solid var(--line);
}

.page-about .next-item:last-child {
  padding-bottom: 0;
  border-bottom: none;
}

.page-about .next-item__idx {
  grid-area: idx;
  font-family: var(--font-num);
  font-size: 32px;
  font-weight: 900;
  line-height: 1;
  letter-spacing: -.02em;
  color: transparent;
  -webkit-text-stroke: 1px var(--lime);
  min-width: 34px;
}

.page-about .next-item h3 {
  grid-area: title;
  margin: 0 0 8px;
  font-size: 17.5px;
  font-weight: 800;
  color: var(--white);
}

.page-about .next-item p {
  grid-area: desc;
  margin: 0;
  font-size: 14.5px;
  line-height: 1.78;
  color: rgba(247, 250, 248, .76);
  max-width: 44ch;
}

@media (min-width: 900px) {
  .page-about .next-list {
    grid-template-columns: repeat(3, 1fr);
    gap: 22px;
  }

  .page-about .next-item {
    grid-template-columns: minmax(0, 1fr);
    grid-template-areas:
      "idx"
      "title"
      "desc";
    row-gap: 10px;
    padding-bottom: 0;
    border-bottom: none;
    border-top: 2px solid var(--line-strong);
    padding-top: 18px;
  }

  .page-about .next-item__idx {
    min-width: 0;
  }
}

/* ---------- 收束 ---------- */
.page-about .about-close {
  padding: clamp(30px, 5vw, 58px) 0 clamp(14px, 3vw, 28px);
  border-top: 1px solid var(--line);
}

.page-about .about-close__inner {
  background: var(--dark-green);
  border: 1px solid var(--line-strong);
  border-left: 5px solid var(--lime);
  padding: clamp(22px, 3.4vw, 34px);
  position: relative;
  overflow: hidden;
}

.page-about .about-close__inner::after {
  content: "";
  position: absolute;
  right: -40px;
  top: -40px;
  width: 160px;
  height: 160px;
  border: 1px solid rgba(200, 255, 61, .2);
  transform: rotate(20deg);
  pointer-events: none;
}

.page-about .about-close__title {
  margin: 0 0 12px;
  font-size: clamp(20px, 3.2vw, 28px);
  font-weight: 800;
  line-height: 1.24;
  color: var(--white);
  letter-spacing: -.01em;
}

.page-about .about-close__text {
  margin: 0 0 22px;
  max-width: 44ch;
  font-size: 15px;
  line-height: 1.78;
  color: rgba(247, 250, 248, .78);
}

.page-about .about-close__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

/* ---------- 进场显现 ---------- */
.page-about [data-reveal] {
  opacity: 1;
}

@media (prefers-reduced-motion: no-preference) {
  .page-about [data-reveal] {
    opacity: 0;
    transform: translateY(10px);
    transition: opacity 420ms var(--ease), transform 420ms var(--ease);
  }

  .page-about [data-reveal].is-visible {
    opacity: 1;
    transform: none;
  }
}