/* ===== 品牌介绍页 · page-about ===== */
.page-about {
  --rail: 116px;
  --rail-gap: 40px;
  background: var(--paper);
  color: var(--ink);
}

/* --- 面包屑 --- */
.page-about .breadcrumbs {
  padding-top: 22px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
}
.page-about .breadcrumbs__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
}
.page-about .breadcrumbs__list li + li::before {
  content: "/";
  margin: 0 8px;
  color: var(--line);
}
.page-about .breadcrumbs__list a {
  color: var(--gray);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color .2s var(--ease), border-color .2s var(--ease);
}
.page-about .breadcrumbs__list a:hover,
.page-about .breadcrumbs__list a:focus-visible {
  color: var(--green);
  border-bottom-color: var(--grass);
}
.page-about .breadcrumbs__list [aria-current="page"] {
  color: var(--ink);
  font-weight: 600;
}

/* --- 首屏 --- */
.page-about .about-hero {
  position: relative;
  padding: 34px 0 0;
}
.page-about .about-hero__eyebrow {
  margin: 0;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--orange);
}
.page-about .about-hero__eyebrow::before {
  content: "";
  width: 28px;
  height: 2px;
  border-radius: 2px;
  background: var(--orange);
}
.page-about .about-hero__title {
  margin: 18px 0 0;
  max-width: 16ch;
  font-size: clamp(30px, 8vw, 66px);
  font-weight: 900;
  line-height: 1.07;
  letter-spacing: -.025em;
}
.page-about .about-hero__title em {
  font-style: normal;
  padding: 0 2px;
  background: linear-gradient(transparent 64%, var(--neon) 64%);
}
.page-about .about-hero__lede {
  margin-top: 26px;
  max-width: 66ch;
}
.page-about .about-hero__lede p {
  margin: 0 0 12px;
  font-size: 16px;
  line-height: 1.85;
}
.page-about .about-hero__lede p:last-child {
  margin-bottom: 0;
  color: var(--gray);
}

/* --- 目录胶囊 --- */
.page-about .about-toc {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 30px;
}
.page-about .about-toc a {
  display: inline-block;
  padding: 9px 15px;
  font-size: 13px;
  letter-spacing: .02em;
  color: var(--ink);
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  text-decoration: none;
  transition: background-color .22s var(--ease), color .22s var(--ease), border-color .22s var(--ease);
}
.page-about .about-toc a:hover,
.page-about .about-toc a:focus-visible {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--paper);
}

.page-about .about-hero__curve {
  display: block;
  width: 100%;
  height: 46px;
  margin-top: 34px;
  color: var(--grass);
  opacity: .5;
}

/* --- 正文骨架 --- */
.page-about .about-body {
  padding-bottom: 0;
}
.page-about .about-chapter {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
  padding: 42px 0;
  border-top: 1px solid var(--line-soft);
}
.page-about .about-body > .about-chapter:first-child {
  border-top: 0;
  padding-top: 30px;
}

/* --- 章节编号栏 --- */
.page-about .chapter-rail {
  display: flex;
  align-items: center;
  gap: 12px;
}
.page-about .chapter-rail__num {
  font-family: var(--font-mono);
  font-size: 40px;
  font-weight: 600;
  line-height: 1;
  letter-spacing: -.05em;
  color: var(--green);
}
.page-about .chapter-rail__label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--gray);
}

/* --- 章节文字 --- */
.page-about .chapter-title {
  margin: 0 0 16px;
  max-width: 20ch;
  font-size: clamp(23px, 4.6vw, 38px);
  font-weight: 800;
  line-height: 1.22;
  letter-spacing: -.015em;
}
.page-about .chapter-lede {
  margin: 0 0 30px;
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.85;
}

/* --- 01 三块内容 --- */
.page-about .problem-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
}
.page-about .problem-list li {
  position: relative;
  overflow: hidden;
  padding: 24px 22px 24px 26px;
  background: var(--white);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  transition: box-shadow .25s var(--ease), transform .25s var(--ease);
}
.page-about .problem-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 4px;
  background: var(--grass);
  transition: width .25s var(--ease), background-color .25s var(--ease);
}
.page-about .problem-list li:hover {
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}
.page-about .problem-list li:hover::before {
  width: 8px;
  background: var(--orange);
}
.page-about .problem-list__title {
  margin: 12px 0 8px;
  font-size: 18px;
  font-weight: 800;
  line-height: 1.4;
}
.page-about .problem-list__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--gray);
}

/* --- 图片容器 --- */
.page-about .chapter-figure {
  margin: 0 0 30px;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--line-soft);
}
.page-about .chapter-figure img {
  display: block;
  width: 100%;
  height: auto;
  max-height: 520px;
  object-fit: cover;
  filter: saturate(.74) contrast(1.04);
}

/* --- 02 三个作业组 --- */
.page-about .team-grid {
  display: grid;
  gap: 22px;
  margin-bottom: 28px;
  padding: 26px 22px;
  background: var(--mist);
  border-radius: var(--radius);
}
.page-about .team-card__num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--green);
  color: var(--white);
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
}
.page-about .team-card__name {
  margin: 12px 0 8px;
  font-size: 17px;
  font-weight: 800;
}
.page-about .team-card__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--gray);
}

/* --- 02 更新节奏 --- */
.page-about .cadence-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line-soft);
}
.page-about .cadence-list li {
  display: grid;
  gap: 6px;
  padding: 16px 0;
  border-bottom: 1px solid var(--line-soft);
}
.page-about .cadence-list__key {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--green);
}
.page-about .cadence-list__val {
  font-size: 15px;
  line-height: 1.75;
}

/* --- 03 覆盖范围 --- */
.page-about .about-chapter--mist {
  border-top: 0;
  margin: 16px 0;
  padding: 36px 20px;
  background: var(--mist);
  border-radius: var(--radius);
}
.page-about .coverage {
  display: grid;
  gap: 24px;
}
.page-about .stat-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}
.page-about .stat {
  padding: 20px 16px;
  background: var(--white);
}
.page-about .stat__num {
  display: block;
  font-family: var(--font-mono);
  font-size: 30px;
  font-weight: 600;
  line-height: 1;
  letter-spacing: -.03em;
}
.page-about .stat__unit {
  margin-left: 3px;
  font-family: var(--font-cn);
  font-size: 14px;
  font-weight: 700;
  color: var(--green);
}
.page-about .stat__label {
  display: block;
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--gray);
}
.page-about .coverage__figure {
  margin: 0;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--line-soft);
}
.page-about .coverage__figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  filter: saturate(.7) contrast(1.05);
}

/* --- 04 时间线 --- */
.page-about .timeline {
  position: relative;
  margin-top: 8px;
}
.page-about .timeline__curve {
  display: none;
}
.page-about .timeline__track {
  list-style: none;
  margin: 0;
  padding: 0 0 14px;
  display: flex;
  gap: 14px;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch;
}
.page-about .timeline__node {
  flex: 0 0 76%;
  scroll-snap-align: start;
  padding: 22px 20px;
  background: var(--white);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  transition: border-color .25s var(--ease);
}
.page-about .timeline__node:hover {
  border-color: var(--grass);
}
.page-about .timeline__year {
  display: inline-block;
  padding: 5px 13px;
  border-radius: var(--radius-pill);
  background: var(--ink);
  color: var(--neon);
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .08em;
}
.page-about .timeline__year--now {
  background: var(--neon);
  color: var(--ink);
}
.page-about .timeline__title {
  margin: 16px 0 8px;
  font-size: 17px;
  font-weight: 800;
  line-height: 1.4;
}
.page-about .timeline__detail {
  margin: 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--gray);
}

/* --- 05 四条理由 --- */
.page-about .reason-list {
  list-style: none;
  margin: 0 0 30px;
  padding: 0;
  display: grid;
  gap: 0;
}
.page-about .reason {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  gap: 14px;
  padding: 20px 0;
  border-top: 1px solid var(--line-soft);
}
.page-about .reason:first-child {
  border-top: 0;
  padding-top: 0;
}
.page-about .reason__index {
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 600;
  line-height: 1.3;
  color: var(--orange);
}
.page-about .reason__title {
  margin: 0 0 8px;
  font-size: 17px;
  font-weight: 800;
  line-height: 1.4;
}
.page-about .reason__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--gray);
}

/* --- 06 合作 --- */
.page-about .partner-list {
  list-style: none;
  margin: 0 0 30px;
  padding: 0;
  display: grid;
  gap: 12px;
}
.page-about .partner-list li {
  display: grid;
  gap: 6px;
  padding: 18px 20px;
  background: var(--white);
  border: 1px solid var(--line-soft);
  border-left: 4px solid var(--green);
  border-radius: var(--radius);
  transition: border-color .25s var(--ease), transform .25s var(--ease);
}
.page-about .partner-list li:hover {
  border-left-color: var(--orange);
  transform: translateY(-2px);
}
.page-about .partner-list__k {
  font-size: 16px;
  font-weight: 800;
}
.page-about .partner-list__v {
  font-size: 14px;
  line-height: 1.78;
  color: var(--gray);
}
.page-about .partner-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* --- 收尾 --- */
.page-about .about-outro {
  margin-top: 16px;
  padding: 38px 0 68px;
  border-top: 1px solid var(--line-soft);
}
.page-about .about-outro__title {
  margin: 0 0 14px;
  font-size: clamp(22px, 4vw, 30px);
  font-weight: 800;
  line-height: 1.3;
}
.page-about .about-outro__text {
  margin: 0 0 24px;
  max-width: 62ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--gray);
}
.page-about .about-outro__links {
  display: grid;
  gap: 12px;
}
.page-about .outro-link {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 18px 20px;
  background: var(--white);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--ink);
  transition: border-color .25s var(--ease), transform .25s var(--ease);
}
.page-about .outro-link:hover,
.page-about .outro-link:focus-visible {
  border-color: var(--grass);
  transform: translateY(-2px);
}
.page-about .outro-link__tag {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .12em;
  padding: 5px 11px;
  border-radius: var(--radius-pill);
  background: var(--ink);
  color: var(--neon);
}
.page-about .outro-link__label {
  font-size: 16px;
  font-weight: 700;
}

/* --- 平板 --- */
@media (min-width: 640px) {
  .page-about .cadence-list li {
    grid-template-columns: 168px minmax(0, 1fr);
    gap: 20px;
    align-items: baseline;
  }
  .page-about .about-outro__links {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .problem-list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
  }
  .page-about .team-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 0;
    padding: 32px 28px;
  }
  .page-about .team-card {
    padding: 0 24px;
    border-left: 1px solid var(--line);
  }
  .page-about .team-card:first-child {
    padding-left: 0;
    border-left: 0;
  }
  .page-about .team-card:last-child {
    padding-right: 0;
  }
  .page-about .partner-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px;
  }
}

/* --- 桌面：左侧竖排编号 + 右侧正文 --- */
@media (min-width: 900px) {
  .page-about .about-chapter {
    grid-template-columns: var(--rail) minmax(0, 1fr);
    gap: var(--rail-gap);
    padding: 70px 0;
  }
  .page-about .chapter-rail {
    position: sticky;
    top: 108px;
    align-self: start;
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }
  .page-about .chapter-rail__num {
    font-size: 84px;
  }
  .page-about .about-chapter--mist {
    padding: 56px 40px;
  }
  .page-about .coverage {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, .85fr);
    gap: 36px;
    align-items: start;
  }
  .page-about .reason-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0 44px;
  }
  .page-about .reason:nth-child(-n+2) {
    border-top: 0;
    padding-top: 0;
  }
  .page-about .timeline__curve {
    display: block;
    position: absolute;
    left: 0;
    top: 18px;
    width: 100%;
    height: 132px;
    color: var(--grass);
    opacity: .45;
    pointer-events: none;
  }
  .page-about .timeline__track {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 18px;
    padding-bottom: 0;
    overflow: visible;
    position: relative;
    z-index: 1;
  }
  .page-about .timeline__node {
    flex: none;
  }
}

@media (hover: hover) and (min-width: 900px) {
  .page-about .timeline__detail {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height .4s var(--ease), opacity .4s var(--ease);
  }
  .page-about .timeline__node:hover .timeline__detail,
  .page-about .timeline__node:focus-within .timeline__detail {
    max-height: 10em;
    opacity: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .problem-list li,
  .page-about .partner-list li,
  .page-about .outro-link,
  .page-about .timeline__node,
  .page-about .timeline__detail {
    transition: none;
  }
  .page-about .problem-list li:hover,
  .page-about .partner-list li:hover,
  .page-about .outro-link:hover {
    transform: none;
  }
}
</main>