.page-about {
  --about-rail: 216px;
  background: var(--ink);
  color: var(--bone);
}

.page-about .crumb {
  padding-top: 14px;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  isolation: isolate;
  padding-block: clamp(20px, 3.2vw, 38px) clamp(30px, 4.6vw, 58px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background:
    repeating-linear-gradient(90deg, rgba(60, 242, 180, 0.055) 0 1px, transparent 1px 84px),
    radial-gradient(90% 120% at 88% -10%, rgba(60, 242, 180, 0.16), transparent 64%);
}

.page-about .about-hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
}

.page-about .about-kicker {
  margin: 0;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--neon);
}

.page-about .about-h1 {
  margin: 0;
  font-family: var(--display);
  font-weight: 800;
  font-size: clamp(2.05rem, 6vw, 4.2rem);
  line-height: 1.03;
  letter-spacing: -0.015em;
  color: var(--bone);
}

.page-about .about-h1 span {
  display: block;
  margin-top: 0.34em;
  font-size: 0.42em;
  line-height: 1.3;
  letter-spacing: 0.02em;
  font-weight: 600;
  color: var(--mint);
}

.page-about .about-lede {
  margin: 0;
  max-width: 64ch;
  font-size: clamp(1rem, 1.15vw, 1.08rem);
  line-height: 1.8;
  color: rgba(234, 245, 239, 0.82);
}

.page-about .about-stats {
  list-style: none;
  margin: 8px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(158px, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-stat {
  display: grid;
  gap: 6px;
  align-content: start;
  padding: 15px 16px 17px;
  background: var(--ink-2);
}

.page-about .about-stat-num {
  font-family: var(--mono);
  font-size: clamp(1.4rem, 2.6vw, 1.85rem);
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--neon);
}

.page-about .about-stat-lbl {
  font-size: 0.82rem;
  line-height: 1.55;
  color: var(--sage);
}

@media (min-width: 900px) {
  .page-about .about-hero-grid {
    grid-template-columns: 200px minmax(0, 1fr);
    column-gap: clamp(28px, 4vw, 64px);
    row-gap: 16px;
    align-items: start;
  }

  .page-about .about-kicker {
    grid-column: 1;
    grid-row: 1;
    padding-top: 10px;
  }

  .page-about .about-h1 {
    grid-column: 2;
    grid-row: 1;
  }

  .page-about .about-lede {
    grid-column: 2;
    grid-row: 2;
  }

  .page-about .about-stats {
    grid-column: 1 / -1;
    grid-row: 3;
    margin-top: 6px;
  }
}

/* ---------- 主体双栏 ---------- */
.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(26px, 4vw, 46px);
  padding-block: clamp(26px, 4.2vw, 52px) clamp(46px, 7vw, 88px);
}

@media (min-width: 960px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    column-gap: clamp(30px, 4.5vw, 72px);
  }
}

.page-about .about-rail {
  display: grid;
  gap: 12px;
  align-content: start;
  min-width: 0;
}

@media (min-width: 960px) {
  .page-about .about-rail {
    position: sticky;
    top: calc(var(--nav-h) + 28px);
    align-self: start;
  }
}

.page-about .rail-title {
  margin: 0;
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--sage);
}

.page-about .rail-toc {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
  min-width: 0;
}

.page-about .rail-toc a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 8px 10px;
  border-left: 2px solid transparent;
  color: var(--mint);
  text-decoration: none;
  font-size: 0.9rem;
  line-height: 1.4;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease), background-color 0.2s var(--ease);
}

.page-about .rail-num {
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.1em;
  color: var(--sage);
}

.page-about .rail-toc a:hover,
.page-about .rail-toc a:focus-visible {
  color: var(--bone);
  border-left-color: var(--neon);
  background: rgba(60, 242, 180, 0.07);
  outline: none;
}

.page-about .rail-note {
  margin: 0;
  padding-top: 10px;
  border-top: 1px solid var(--line);
  font-family: var(--mono);
  font-size: 10.5px;
  line-height: 1.8;
  letter-spacing: 0.08em;
  color: var(--sage);
}

@media (max-width: 959px) {
  .page-about .rail-toc {
    grid-auto-flow: column;
    grid-auto-columns: max-content;
    gap: 6px;
    overflow-x: auto;
    padding-bottom: 4px;
    scrollbar-width: thin;
  }

  .page-about .rail-toc a {
    border: 1px solid var(--line);
    border-radius: 999px;
    padding: 7px 14px;
    font-size: 0.84rem;
  }

  .page-about .rail-toc a:hover,
  .page-about .rail-toc a:focus-visible {
    border-color: var(--neon);
  }

  .page-about .rail-note {
    border-top: 0;
    padding-top: 0;
  }
}

/* ---------- 章节 ---------- */
.page-about .about-flow {
  min-width: 0;
}

.page-about .about-sec {
  padding-block: clamp(28px, 4vw, 52px);
  border-top: 1px solid var(--line);
  scroll-margin-top: calc(var(--nav-h) + 24px);
}

.page-about .about-sec:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .sec-head {
  display: grid;
  gap: 10px;
  margin-bottom: clamp(16px, 2.4vw, 26px);
}

.page-about .sec-num {
  margin: 0;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--neon);
}

.page-about .sec-h2 {
  margin: 0;
  max-width: 26ch;
  font-family: var(--display);
  font-weight: 800;
  font-size: clamp(1.5rem, 3.1vw, 2.3rem);
  line-height: 1.12;
  letter-spacing: -0.01em;
  color: var(--bone);
}

.page-about .sec-p {
  margin: 0 0 14px;
  max-width: 72ch;
  font-size: 1rem;
  line-height: 1.8;
  color: rgba(234, 245, 239, 0.86);
}

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

.page-about .sec-split {
  display: grid;
  gap: clamp(18px, 3vw, 32px);
}

@media (min-width: 820px) {
  .page-about .sec-split {
    grid-template-columns: minmax(0, 1.45fr) minmax(0, 1fr);
    align-items: start;
  }
}

/* ---------- 图片 ---------- */
.page-about .about-figure {
  margin: 0;
  display: grid;
  gap: 10px;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--line);
  filter: saturate(0.8) contrast(1.02) brightness(0.9);
}

.page-about .about-figure figcaption {
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--sage);
}

.page-about .about-sec .about-figure {
  margin-top: 6px;
}

.page-about .about-sec .about-figure + .sec-p {
  margin-top: 20px;
}

/* ---------- 归档标准 ---------- */
.page-about .std-list {
  list-style: none;
  margin: 20px 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .std-item {
  display: grid;
  gap: 6px;
  padding: 15px 18px;
  background: var(--card);
  border: 1px solid var(--line);
  border-left: 3px solid var(--neon);
}

.page-about .std-item h3 {
  margin: 0;
  font-size: 0.98rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--bone);
}

.page-about .std-item p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.72;
  color: var(--sage);
}

/* ---------- 三步路径 ---------- */
.page-about .path-steps {
  list-style: none;
  margin: 20px 0 0;
  padding: 0;
  display: grid;
  gap: 0;
  counter-reset: none;
}

.page-about .path-step {
  padding: 16px 0 18px;
  border-top: 2px solid var(--line);
}

.page-about .path-step--on {
  border-top-color: var(--neon);
}

.page-about .path-idx {
  display: block;
  margin-bottom: 8px;
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.18em;
  color: var(--neon);
}

.page-about .path-step h3 {
  margin: 0 0 6px;
  font-family: var(--display);
  font-size: 1.28rem;
  font-weight: 700;
  letter-spacing: -0.005em;
  color: var(--bone);
}

.page-about .path-step p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.72;
  color: var(--sage);
}

@media (min-width: 760px) {
  .page-about .path-steps {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    column-gap: clamp(16px, 2.4vw, 30px);
  }

  .page-about .path-step {
    padding: 18px 0 0;
  }
}

/* ---------- 版本时间轴 ---------- */
.page-about .vtl {
  list-style: none;
  position: relative;
  margin: 22px 0 0;
  padding: 0 0 0 24px;
  display: grid;
  gap: 8px;
}

.page-about .vtl::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 14px;
  bottom: 14px;
  width: 1px;
  background: linear-gradient(180deg, var(--neon), var(--line) 72%);
}

.page-about .vtl-item {
  position: relative;
}

.page-about .vtl-item::before {
  content: "";
  position: absolute;
  left: -24px;
  top: 15px;
  width: 11px;
  height: 11px;
  box-sizing: border-box;
  border-radius: 50%;
  background: var(--ink);
  border: 2px solid var(--neon);
}

.page-about .vtl-det {
  background: var(--card);
  border: 1px solid var(--line);
}

.page-about .vtl-sum {
  list-style: none;
  cursor: pointer;
  position: relative;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: baseline;
  gap: 4px 12px;
  padding: 13px 40px 13px 16px;
}

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

.page-about .vtl-sum::after {
  content: "+";
  position: absolute;
  right: 14px;
  top: 11px;
  font-family: var(--mono);
  font-size: 15px;
  line-height: 1;
  color: var(--neon);
}

.page-about .vtl-det[open] .vtl-sum::after {
  content: "–";
}

.page-about .vtl-sum:focus-visible {
  outline: 2px solid var(--neon);
  outline-offset: -2px;
}

.page-about .vtl-tag {
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.1em;
  color: var(--gold);
}

.page-about .vtl-name {
  font-size: 0.94rem;
  line-height: 1.55;
  color: var(--bone);
}

.page-about .vtl-body {
  padding: 0 16px 15px;
}

.page-about .vtl-body p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.72;
  color: var(--sage);
}

/* ---------- 使用场景 ---------- */
.page-about .scene-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
}

.page-about .scene-card {
  display: grid;
  gap: 7px;
  align-content: start;
  padding: 18px 18px 20px;
  background: var(--bone);
  color: var(--char);
  clip-path: polygon(0 12px, 12px 0, 100% 0, 100% 100%, 0 100%);
}

.page-about .scene-tag {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: #46765f;
}

.page-about .scene-card h3 {
  margin: 0;
  font-size: 0.98rem;
  font-weight: 800;
  letter-spacing: -0.005em;
  color: #10201a;
}

.page-about .scene-card p {
  margin: 0;
  font-size: 0.89rem;
  line-height: 1.68;
  color: #2c3a34;
}

@media (min-width: 680px) {
  .page-about .scene-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1040px) {
  .page-about .scene-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

/* ---------- 服务支持 ---------- */
.page-about .support-box {
  display: grid;
  gap: clamp(18px, 2.6vw, 28px);
  padding: clamp(20px, 3vw, 30px);
  background: var(--ink-2);
  border: 1px solid var(--line);
  border-top: 2px solid var(--gold);
}

@media (min-width: 780px) {
  .page-about .support-box {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
    align-items: start;
  }
}

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

.page-about .support-list li {
  display: grid;
  gap: 3px;
  padding-left: 14px;
  border-left: 1px solid var(--line);
}

.page-about .support-k {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--sage);
}

.page-about .support-v {
  font-size: 0.92rem;
  line-height: 1.6;
  color: var(--bone);
  word-break: break-word;
}

.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}

.page-about .about-actions .btn {
  text-decoration: none;
}

@media (prefers-reduced-motion: reduce) {
  .page-about .rail-toc a,
  .page-about .vtl-det {
    transition: none;
  }
}