/* ============================================================
   page-about · 品牌概况
   层叠目录式阅读：左侧阶段索引，右侧叙述与旁注交替
   ============================================================ */

.page-about {
  --about-rail: 252px;
  background: var(--ink-0);
  color: var(--body);
}

/* ---------- 首屏横幅 ---------- */

.page-about .about-hero {
  position: relative;
  overflow: hidden;
  background: var(--ink-0);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero-media {
  position: absolute;
  inset: 0;
}

.page-about .about-hero-media img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.44;
}

.page-about .about-hero-media::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(100deg,
      rgba(7, 14, 27, 0.97) 0%,
      rgba(7, 14, 27, 0.86) 44%,
      rgba(7, 14, 27, 0.4) 100%);
}

.page-about .about-hero-inner {
  position: relative;
  padding-top: 44px;
  padding-bottom: 44px;
}

.page-about .breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-bottom: 20px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--gray);
}

.page-about .breadcrumbs a {
  color: var(--gray);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 120ms var(--ease), border-color 120ms var(--ease);
}

.page-about .breadcrumbs a:hover,
.page-about .breadcrumbs a:focus-visible {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

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

.page-about .about-hero .eyebrow {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--cyan);
}

.page-about .about-hero h1 {
  margin: 14px 0 0;
  max-width: 17em;
  font-family: var(--font-cond);
  font-weight: 600;
  font-size: clamp(30px, 7.2vw, 58px);
  line-height: 1.08;
  letter-spacing: 0.01em;
  color: var(--frost);
}

.page-about .about-hero .lede {
  margin: 18px 0 0;
  max-width: 60ch;
  font-size: 15.5px;
  line-height: 1.78;
  color: var(--body);
}

.page-about .hero-facts {
  list-style: none;
  margin: 28px 0 0;
  padding: 1px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  max-width: 720px;
}

.page-about .hero-facts li {
  background: rgba(14, 27, 48, 0.86);
  padding: 12px 14px;
}

.page-about .fact-k {
  display: block;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: var(--gray);
}

.page-about .fact-v {
  display: block;
  margin-top: 5px;
  font-family: var(--font-mono);
  font-size: 19px;
  font-weight: 500;
  font-variant-numeric: tabular-nums;
  color: var(--frost);
}

/* ---------- 主体双栏 ---------- */

.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 26px;
  padding-top: 32px;
  padding-bottom: 64px;
}

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

/* ---------- 左侧阶段索引 ---------- */

.page-about .about-rail {
  padding: 14px 14px 16px;
  background: var(--ink-1);
  border: 1px solid var(--line);
  clip-path: var(--cut-sm);
}

.page-about .rail-title {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.14em;
  color: var(--gray);
}

.page-about .rail-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 6px;
  overflow-x: auto;
  scrollbar-width: none;
}

.page-about .rail-list::-webkit-scrollbar {
  display: none;
}

.page-about .rail-link {
  display: flex;
  align-items: baseline;
  gap: 9px;
  padding: 8px 11px;
  white-space: nowrap;
  text-decoration: none;
  color: var(--body);
  background: transparent;
  border-left: 2px solid transparent;
  font-size: 13.5px;
  transition: background-color 120ms var(--ease),
    border-color 120ms var(--ease), color 120ms var(--ease);
}

.page-about .rail-link:hover,
.page-about .rail-link:focus-visible {
  background: var(--ink-2);
  border-left-color: var(--cyan);
  color: var(--frost);
  outline: none;
}

.page-about .rail-num {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--cyan);
}

/* ---------- 章节骨架 ---------- */

.page-about .about-sec {
  scroll-margin-top: 92px;
  padding-bottom: 32px;
  margin-bottom: 34px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-sec:last-of-type {
  padding-bottom: 0;
  margin-bottom: 34px;
  border-bottom: 0;
}

.page-about .sec-row {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line);
}

.page-about .sec-num {
  flex: none;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--cyan);
}

.page-about .sec-title {
  margin: 0;
  font-family: var(--font-cond);
  font-weight: 600;
  font-size: clamp(23px, 4.6vw, 32px);
  line-height: 1.16;
  letter-spacing: 0.01em;
  color: var(--frost);
  transition: color 120ms var(--ease);
}

.page-about .about-sec:target .sec-title {
  color: var(--cyan);
}

/* ---------- 正文与旁注 ---------- */

.page-about .prose {
  max-width: 66ch;
}

.page-about .prose p {
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.78;
  color: var(--body);
}

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

.page-about .note-card {
  max-width: 66ch;
  margin-top: 20px;
  padding: 14px 16px;
  background: rgba(14, 143, 132, 0.09);
  border: 1px solid var(--cyan-deep);
  clip-path: var(--cut-sm);
}

.page-about .note-label {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--cyan);
}

.page-about .note-card p {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.72;
  color: var(--body);
}

/* ---------- 使用人群 ---------- */

.page-about .audience-list {
  list-style: none;
  margin: 20px 0 0;
  padding: 1px;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .audience-item {
  display: grid;
  grid-template-columns: 30px minmax(0, 1fr);
  gap: 12px;
  padding: 15px 16px;
  background: var(--ink-1);
  transition: background-color 120ms var(--ease);
}

.page-about .audience-item:hover {
  background: var(--ink-2);
}

.page-about .audience-key {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--cyan);
  padding-top: 2px;
}

.page-about .audience-body h3 {
  margin: 0 0 7px;
  font-size: 15px;
  font-weight: 600;
  line-height: 1.4;
  color: var(--frost);
}

.page-about .audience-body p {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.72;
  color: var(--body);
}

/* ---------- 图形容器 ---------- */

.page-about .media-frame {
  margin: 22px 0 0;
  padding: 0;
  background: var(--ink-1);
  border: 1px solid var(--line);
  clip-path: var(--cut);
  overflow: hidden;
}

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

.page-about .media-cap {
  padding: 10px 14px;
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 11.5px;
  line-height: 1.6;
  letter-spacing: 0.04em;
  color: var(--gray);
}

/* ---------- 内容分类条目 ---------- */

.page-about .entry-list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

.page-about .entry {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 5px;
  padding: 14px 2px;
  border-bottom: 1px solid var(--line);
}

.page-about .entry-name {
  display: flex;
  align-items: baseline;
  gap: 10px;
  font-size: 15px;
  font-weight: 600;
  color: var(--frost);
}

.page-about .entry-code {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.06em;
  color: var(--cyan);
}

.page-about .entry-desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.72;
  color: var(--body);
}

/* ---------- 发展节点时间轴 ---------- */

.page-about .timeline {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
}

.page-about .tl-item {
  position: relative;
  padding: 0 0 22px 26px;
  border-left: 1px solid var(--line);
}

.page-about .tl-item:last-child {
  padding-bottom: 0;
}

.page-about .tl-item::before {
  content: "";
  position: absolute;
  left: 3px;
  top: 9px;
  width: 12px;
  height: 1px;
  background: var(--cyan);
  transform: rotate(-45deg);
}

.page-about .tl-phase {
  margin: 0 0 5px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.12em;
  color: var(--orange);
}

.page-about .tl-item h3 {
  margin: 0 0 7px;
  font-size: 15px;
  font-weight: 600;
  line-height: 1.44;
  color: var(--frost);
}

.page-about .tl-item p {
  margin: 0;
  max-width: 62ch;
  font-size: 14px;
  line-height: 1.74;
  color: var(--body);
}

/* ---------- 团队分工折叠面板 ---------- */

.page-about .fold {
  margin-top: 20px;
  background: var(--ink-1);
  border: 1px solid var(--line);
  clip-path: var(--cut-sm);
}

.page-about .fold-mark {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  padding: 13px 16px;
  cursor: pointer;
  list-style: none;
  transition: background-color 120ms var(--ease);
}

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

.page-about .fold-mark:hover,
.page-about .fold-mark:focus-visible {
  background: var(--ink-2);
}

.page-about .fold-title {
  font-size: 14.5px;
  font-weight: 600;
  color: var(--frost);
}

.page-about .fold-note {
  flex: none;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: var(--cyan);
}

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

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

.page-about .team-list li {
  padding: 10px 0;
  border-top: 1px solid var(--line);
  font-size: 13.5px;
  line-height: 1.74;
  color: var(--body);
}

.page-about .team-key {
  display: inline-block;
  margin-right: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--cyan);
}

/* ---------- 相关入口 ---------- */

.page-about .about-next {
  margin-top: 34px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.page-about .about-next-title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.14em;
  color: var(--gray);
}

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

.page-about .about-next-list a {
  display: block;
  padding: 13px 16px;
  background: var(--ink-1);
  text-decoration: none;
  border-left: 2px solid transparent;
  transition: background-color 120ms var(--ease),
    border-color 120ms var(--ease);
}

.page-about .about-next-list a:hover,
.page-about .about-next-list a:focus-visible {
  background: var(--ink-2);
  border-left-color: var(--cyan);
  outline: none;
}

.page-about .nx-main {
  display: block;
  font-size: 14.5px;
  font-weight: 600;
  color: var(--frost);
}

.page-about .nx-sub {
  display: block;
  margin-top: 4px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--gray);
}

/* ---------- 焦点可达性 ---------- */

.page-about a:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

/* ============================================================
   响应式
   ============================================================ */

@media (min-width: 640px) {
  .page-about .hero-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .page-about .entry {
    grid-template-columns: 168px minmax(0, 1fr);
    gap: 20px;
    align-items: baseline;
  }
}

@media (min-width: 768px) {
  .page-about .audience-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-hero-inner {
    padding-top: 64px;
    padding-bottom: 58px;
  }
}

@media (min-width: 1024px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: 56px;
    padding-top: 52px;
    padding-bottom: 84px;
  }

  .page-about .about-rail {
    position: sticky;
    top: 88px;
    align-self: start;
  }

  .page-about .rail-list {
    flex-direction: column;
    gap: 2px;
    overflow: visible;
  }

  .page-about .rail-link {
    white-space: normal;
  }

  .page-about .about-sec {
    padding-bottom: 38px;
    margin-bottom: 42px;
  }
}

@media (min-width: 1280px) {
  .page-about .about-hero-inner {
    padding-top: 76px;
    padding-bottom: 68px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition-duration: 0ms !important;
  }
}