.page-about {
  --about-panel: rgba(255, 255, 255, 0.03);
  --about-line-soft: rgba(255, 255, 255, 0.08);
  display: block;
  background: var(--night);
  color: var(--white);
  font-family: var(--font-body);
}

.page-about *,
.page-about *::before,
.page-about *::after {
  box-sizing: border-box;
}

/* ---------- 面包屑 ---------- */
.page-about .breadcrumb {
  max-width: var(--rail-w);
  margin: 0 auto;
  padding: 18px var(--edge) 0;
}

.page-about .breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--ink-3);
}

.page-about .breadcrumb li {
  display: flex;
  align-items: center;
  gap: 8px;
}

.page-about .breadcrumb li + li::before {
  content: "/";
  color: var(--slate);
}

.page-about .breadcrumb a {
  color: var(--ink-2);
  text-decoration: none;
  transition: color 0.2s ease;
}

.page-about .breadcrumb a:hover,
.page-about .breadcrumb a:focus-visible {
  color: var(--fire);
}

.page-about .breadcrumb [aria-current="page"] {
  color: var(--fire);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding: clamp(36px, 5.5vw, 80px) var(--edge) clamp(44px, 6vw, 88px);
  background:
    radial-gradient(115% 85% at 96% 2%, rgba(255, 91, 27, 0.26), transparent 62%),
    linear-gradient(180deg, var(--night) 0%, var(--night-deep) 100%);
  border-bottom: 1px solid var(--hairline);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.05) 1px, transparent 1px);
  background-size: 64px 64px;
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.9), transparent 78%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.9), transparent 78%);
  pointer-events: none;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  right: -8%;
  top: -14%;
  width: 48%;
  height: 72%;
  background: linear-gradient(135deg, var(--fire), var(--fire-deep));
  clip-path: polygon(14% 0, 100% 0, 86% 100%, 0 100%);
  transform: rotate(-8deg);
  opacity: 0.16;
  pointer-events: none;
}

.page-about .about-hero__grid {
  position: relative;
  z-index: 1;
  max-width: var(--rail-w);
  margin: 0 auto;
  display: grid;
  gap: clamp(28px, 4vw, 48px);
}

.page-about .about-hero h1 {
  margin: 14px 0 18px;
  max-width: 22ch;
}

.page-about .about-hero .lead {
  max-width: 42ch;
  color: var(--ink-2);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

.page-about .about-hero__board {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--hairline);
  border: 1px solid var(--hairline-fire);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.page-about .about-hero__board .stat {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 18px 16px;
  background: rgba(14, 16, 20, 0.72);
}

.page-about .about-hero__board .stat-value {
  font-family: var(--font-mono);
  font-size: clamp(1.45rem, 3.2vw, 2rem);
  font-weight: 700;
  letter-spacing: 0.04em;
  line-height: 1.1;
  color: var(--white);
}

.page-about .about-hero__board .stat-value--up {
  color: var(--lime);
}

.page-about .about-hero__board .stat-label {
  font-size: 12.5px;
  letter-spacing: 0.04em;
  color: var(--ink-3);
}

/* ---------- 历程区骨架 ---------- */
.page-about .about-archive {
  padding: clamp(44px, 6vw, 80px) 0 clamp(36px, 5vw, 64px);
  background: linear-gradient(180deg, var(--night-deep) 0%, var(--night) 26%, var(--night) 100%);
}

.page-about .archive-shell {
  max-width: var(--rail-w);
  margin: 0 auto;
  padding: 0 var(--edge);
  display: grid;
  grid-template-columns: minmax(0, 1fr);
}

.page-about .year-rail {
  display: none;
}

/* ---------- 年份节点 ---------- */
.page-about .era {
  position: relative;
  padding: clamp(30px, 4.5vw, 56px) 0 clamp(34px, 5vw, 60px);
  border-top: 1px solid var(--hairline);
}

.page-about .era:first-child {
  border-top-color: transparent;
  padding-top: 0;
}

.page-about .era[data-active="true"]::before {
  content: "";
  position: absolute;
  left: -12px;
  top: clamp(30px, 4.5vw, 56px);
  bottom: clamp(34px, 5vw, 60px);
  width: 3px;
  border-radius: 3px;
  background: linear-gradient(180deg, var(--fire), rgba(255, 91, 27, 0));
}

.page-about .era-year {
  display: inline-flex;
  align-items: center;
  margin: 0 0 14px;
  padding: 5px 13px;
  border: 1px solid var(--hairline-fire);
  border-radius: var(--radius-pill);
  background: rgba(255, 91, 27, 0.08);
  color: var(--fire);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.16em;
}

.page-about .era[data-active="true"] .era-year {
  border-color: var(--fire);
  color: var(--fire-soft);
}

.page-about .era .section-title {
  margin: 0 0 14px;
}

.page-about .era-intro {
  max-width: 62ch;
  margin: 0 0 26px;
  color: var(--ink-2);
  font-size: 16.5px;
  line-height: 1.85;
}

.page-about .era-body {
  display: grid;
  gap: clamp(24px, 3vw, 40px);
}

.page-about .era-body .prose {
  max-width: 36em;
  font-size: 17px;
  line-height: 1.85;
  color: var(--ink-2);
}

.page-about .era-body .prose p {
  margin: 0 0 16px;
}

/* ---------- 图片容器 ---------- */
.page-about .media {
  margin: 0;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: var(--slate);
}

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

.page-about .media--grid img {
  filter: saturate(0.95) contrast(1.05);
}

.page-about .media-caption {
  padding: 12px 14px;
  border-top: 1px solid var(--hairline);
  background: rgba(14, 16, 20, 0.9);
  color: var(--ink-3);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  line-height: 1.6;
}

/* ---------- 六步流程 ---------- */
.page-about .flow-list {
  position: relative;
  margin: 0 0 30px;
  padding: 0;
  list-style: none;
}

.page-about .flow-list::before {
  content: "";
  position: absolute;
  left: 19px;
  top: 14px;
  bottom: 14px;
  width: 2px;
  border-radius: 2px;
  background: linear-gradient(180deg, var(--fire), rgba(255, 91, 27, 0.14));
}

.page-about .flow-step {
  position: relative;
  margin-bottom: 12px;
  padding-left: 52px;
}

.page-about .flow-step .flow-index {
  position: absolute;
  left: 0;
  top: 12px;
  z-index: 1;
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border: 2px solid var(--fire);
  border-radius: 50%;
  background: var(--night-deep);
  color: var(--fire);
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.page-about .flow-step summary {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  padding: 12px 14px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  background: var(--about-panel);
  cursor: pointer;
  list-style: none;
  transition: border-color 0.2s ease, background 0.2s ease;
}

.page-about .flow-step summary::-webkit-details-marker {
  display: none;
}

.page-about .flow-step summary:hover {
  border-color: var(--hairline-fire);
  background: rgba(255, 91, 27, 0.07);
}

.page-about .flow-step summary:focus-visible {
  outline: 2px solid var(--sky);
  outline-offset: 2px;
}

.page-about .flow-step[open] summary {
  border-color: var(--fire);
  border-bottom-left-radius: 0;
  border-bottom-right-radius: 0;
  background: rgba(255, 91, 27, 0.1);
}

.page-about .flow-name {
  font-size: 16px;
  font-weight: 700;
  margin-left: 6px;
}

.page-about .flow-owner {
  margin-left: auto;
  padding: 3px 10px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-pill);
  color: var(--ink-3);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
}

.page-about .flow-body {
  padding: 14px 16px 18px;
  border: 1px solid var(--hairline);
  border-top: 0;
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  background: rgba(14, 16, 20, 0.6);
}

.page-about .flow-body p {
  margin: 0 0 14px;
  color: var(--ink-2);
  font-size: 15.5px;
  line-height: 1.8;
}

.page-about .flow-meta {
  display: grid;
  gap: 10px;
  margin: 0;
}

.page-about .flow-meta dt {
  margin-bottom: 4px;
  color: var(--ink-3);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
}

.page-about .flow-meta dd {
  margin: 0;
  color: var(--white);
  font-size: 14px;
  line-height: 1.6;
}

/* ---------- 团队分工 ---------- */
.page-about .team-bars {
  display: grid;
  gap: 16px;
  margin: 0 0 22px;
  padding: 0;
  list-style: none;
}

.page-about .team-row {
  padding: 16px 18px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  background: var(--about-panel);
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.page-about .team-row:hover {
  border-color: var(--hairline-fire);
  transform: translateY(-2px);
}

.page-about .team-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 10px;
}

.page-about .team-name {
  font-size: 16px;
  font-weight: 700;
}

.page-about .team-num {
  color: var(--fire);
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 700;
  letter-spacing: 0.06em;
}

.page-about .team-track {
  height: 8px;
  border-radius: var(--radius-pill);
  background: rgba(255, 255, 255, 0.07);
  overflow: hidden;
}

.page-about .team-fill {
  display: block;
  height: 100%;
  width: var(--bar, 0%);
  border-radius: var(--radius-pill);
  background: linear-gradient(90deg, var(--fire-deep), var(--fire) 60%, var(--fire-soft));
}

.page-about .team-row:hover .team-fill {
  background: linear-gradient(90deg, var(--fire), var(--fire-soft) 70%, var(--lime));
}

.page-about .team-desc {
  margin: 10px 0 0;
  color: var(--ink-2);
  font-size: 14.5px;
  line-height: 1.75;
}

.page-about .version-note {
  margin: 0;
  padding: 16px 18px;
  border-left: 3px solid var(--fire);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  background: rgba(255, 91, 27, 0.07);
  color: var(--ink-2);
  font-size: 15px;
  line-height: 1.8;
}

/* ---------- 算法约定 ---------- */
.page-about .std-grid {
  display: grid;
  gap: 14px;
}

.page-about .std-card {
  padding: 18px 18px 20px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  background: linear-gradient(160deg, rgba(255, 91, 27, 0.09), rgba(255, 255, 255, 0.02) 48%);
}

.page-about .std-card .tag {
  display: inline-block;
  font-size: 12px;
}

.page-about .std-card p {
  margin: 10px 0 0;
  color: var(--ink-2);
  font-size: 15px;
  line-height: 1.8;
}

/* ---------- 覆盖范围 ---------- */
.page-about .region-grid {
  display: grid;
  gap: 1px;
  margin-bottom: 26px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  background: var(--hairline);
  overflow: hidden;
}

.page-about .region {
  background: var(--night);
}

.page-about .region summary {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 16px 18px;
  font-size: 15px;
  font-weight: 700;
  cursor: pointer;
  list-style: none;
  transition: background 0.2s ease;
}

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

.page-about .region summary::after {
  content: "+";
  color: var(--fire);
  font-family: var(--font-mono);
  font-size: 15px;
}

.page-about .region[open] summary::after {
  content: "−";
}

.page-about .region summary:hover {
  background: rgba(255, 91, 27, 0.08);
}

.page-about .region summary:focus-visible {
  outline: 2px solid var(--sky);
  outline-offset: -2px;
}

.page-about .region-count {
  margin-left: auto;
  color: var(--fire-soft);
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
}

.page-about .region p {
  margin: 0;
  padding: 12px 18px 16px;
  border-top: 1px solid var(--hairline);
  color: var(--ink-2);
  font-size: 14px;
  line-height: 1.75;
}

.page-about .partner-strip {
  display: grid;
  gap: 12px;
  margin-top: 24px;
}

.page-about .partner-item {
  padding: 16px 18px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  background: var(--about-panel);
}

.page-about .partner-item strong {
  display: block;
  margin-bottom: 6px;
  color: var(--fire);
  font-family: var(--font-mono);
  font-size: 24px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.page-about .partner-item span {
  color: var(--ink-2);
  font-size: 14px;
  line-height: 1.7;
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  position: relative;
  overflow: hidden;
  padding: clamp(46px, 7vw, 96px) var(--edge);
  background: linear-gradient(135deg, var(--fire-deep) 0%, #7a2202 46%, var(--night) 100%);
  border-top: 1px solid var(--hairline-fire);
}

.page-about .about-next::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.06) 1px, transparent 1px);
  background-size: 56px 56px;
  opacity: 0.5;
  pointer-events: none;
}

.page-about .about-next__inner {
  position: relative;
  z-index: 1;
  max-width: var(--rail-w);
  margin: 0 auto;
}

.page-about .about-next .section-title {
  margin: 10px 0 26px;
  color: var(--white);
}

.page-about .next-list {
  display: grid;
  gap: 14px;
  margin: 0 0 30px;
  padding: 0;
  list-style: none;
}

.page-about .next-list li {
  padding: 20px;
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: var(--radius-md);
  background: rgba(14, 16, 20, 0.42);
}

.page-about .next-num {
  display: block;
  margin-bottom: 10px;
  color: var(--lime);
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.2em;
}

.page-about .next-list h3 {
  margin: 0 0 8px;
  font-size: 18px;
  line-height: 1.5;
  color: var(--white);
}

.page-about .next-list p {
  margin: 0;
  color: var(--ink-2);
  font-size: 14.5px;
  line-height: 1.8;
}

.page-about .about-next__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .next-note {
  margin: 20px 0 0;
  color: var(--ink-2);
  font-size: 14px;
  line-height: 1.8;
}

.page-about .next-note a {
  color: var(--lime);
  text-decoration: none;
  border-bottom: 1px solid rgba(183, 255, 60, 0.45);
}

.page-about .next-note a:hover,
.page-about .next-note a:focus-visible {
  color: var(--white);
  border-bottom-color: var(--white);
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .region-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 700px) {
  .page-about .flow-meta {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .std-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .partner-strip {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 860px) {
  .page-about .next-list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .page-about .era-body {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    align-items: start;
  }

  .page-about .team-bars {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 960px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, 0.65fr);
    align-items: end;
  }
}

@media (min-width: 1000px) {
  .page-about .region-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 1040px) {
  .page-about .archive-shell {
    grid-template-columns: 190px minmax(0, 1fr);
    gap: clamp(28px, 4vw, 68px);
  }

  .page-about .year-rail {
    display: block;
    position: sticky;
    top: 128px;
    align-self: start;
    padding: 4px 0 4px 18px;
    border-left: 2px solid var(--hairline);
  }

  .page-about .year-rail__title {
    display: block;
    margin-bottom: 14px;
    color: var(--ink-3);
    font-family: var(--font-mono);
    font-size: 11px;
    letter-spacing: 0.22em;
    text-transform: uppercase;
  }

  .page-about .year-rail a {
    position: relative;
    display: block;
    padding: 9px 0;
    color: var(--ink-3);
    font-size: 13px;
    text-decoration: none;
    transition: color 0.2s ease;
  }

  .page-about .year-rail a span {
    margin-right: 8px;
    color: var(--ink-2);
    font-family: var(--font-mono);
    font-weight: 700;
    letter-spacing: 0.06em;
  }

  .page-about .year-rail a::before {
    content: "";
    position: absolute;
    left: -23px;
    top: 50%;
    width: 8px;
    height: 8px;
    margin-top: -4px;
    border-radius: 50%;
    background: var(--slate);
    transition: background 0.2s ease, box-shadow 0.2s ease;
  }

  .page-about .year-rail a:hover,
  .page-about .year-rail a:focus-visible {
    color: var(--fire-soft);
  }

  .page-about .year-rail a:hover span,
  .page-about .year-rail a:focus-visible span {
    color: var(--fire);
  }

  .page-about .year-rail a:hover::before,
  .page-about .year-rail a:focus-visible::before {
    background: var(--fire);
    box-shadow: 0 0 0 4px rgba(255, 91, 27, 0.18);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .team-row,
  .page-about .flow-step summary,
  .page-about .year-rail a,
  .page-about .year-rail a::before {
    transition: none;
  }

  .page-about .team-row:hover {
    transform: none;
  }
}

.page-about {
  --bar: 1rem;
}