.page-about {
  --about-rail: 288px;
  --about-hair: rgba(58, 90, 80, 0.42);
  background-color: var(--ink);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.75;
  padding-bottom: 88px;
}

.page-about .about-shell {
  max-width: var(--shell);
  margin: 0 auto;
  padding-left: var(--gutter);
  padding-right: var(--gutter);
}

.page-about .about-top {
  padding-top: 124px;
}

.page-about .crumbs {
  margin-bottom: 36px;
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 36px;
  padding-bottom: 52px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-eyebrow {
  margin: 0 0 10px;
  font-size: 12px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--cyan);
}

.page-about .about-hero h1 {
  margin: 0 0 20px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 34px;
  line-height: 1.16;
  letter-spacing: 0.01em;
  color: var(--text);
}

.page-about .about-hero__intro {
  max-width: 60ch;
  margin: 0 0 28px;
  font-size: 17px;
  color: var(--muted);
}

.page-about .about-hero__cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 18px;
}

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

.page-about .about-figures .stat {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 18px 16px;
  background-color: var(--panel);
}

.page-about .about-figures .stat__num {
  font-family: var(--font-mono);
  font-size: 30px;
  line-height: 1;
  color: var(--cyan);
}

.page-about .about-figures .stat__lab {
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}

/* ---------- 正文骨架 ---------- */

.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 32px;
  padding-top: 56px;
}

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

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

.page-about .about-sect {
  padding-top: 34px;
  margin-bottom: 76px;
  border-top: 1px solid var(--line);
  scroll-margin-top: 120px;
}

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

.page-about .about-sect--last {
  margin-bottom: 0;
}

.page-about .about-sect h2 {
  margin: 0 0 20px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 27px;
  line-height: 1.24;
  letter-spacing: 0.01em;
}

.page-about .about-sect > p {
  max-width: 68ch;
  margin: 0 0 18px;
  color: var(--text);
}

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

.page-about .about-sect a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .about-sect a:hover {
  color: var(--cyan-soft);
  border-bottom-color: var(--cyan-soft);
}

/* ---------- 配图 ---------- */

.page-about .about-figure {
  position: relative;
  margin: 30px 0;
  border: 1px solid var(--line);
  background-color: var(--panel);
}

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

.page-about .about-figure figcaption {
  padding: 12px 16px;
  border-top: 1px solid var(--line);
  font-size: 13px;
  line-height: 1.6;
  color: var(--muted);
}

.page-about .about-figure::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  box-shadow: inset 0 0 90px rgba(43, 232, 200, 0.07);
}

/* ---------- 三道校验 ---------- */

.page-about .method-steps {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background-color: var(--line);
  border: 1px solid var(--line);
}

.page-about .method-step {
  padding: 22px 20px;
  background-color: var(--panel);
  background-image:
    linear-gradient(var(--about-hair) 1px, transparent 1px),
    linear-gradient(90deg, var(--about-hair) 1px, transparent 1px);
  background-size: 30px 30px;
  transition: background-color var(--dur) var(--ease);
}

.page-about .method-step:hover {
  background-color: var(--panel-2);
}

.page-about .method-step__no {
  margin: 0 0 8px;
  font-size: 12px;
  letter-spacing: 0.09em;
  color: var(--cyan);
}

.page-about .method-step__lead {
  margin: 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--text);
}

.page-about .method-step__more {
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
}

.page-about .method-step__more summary {
  cursor: pointer;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--cyan);
}

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

.page-about .method-step__more summary::after {
  content: " +";
}

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

.page-about .method-step__more summary:focus-visible {
  outline: 1px solid var(--cyan);
  outline-offset: 3px;
}

.page-about .method-step__more ul {
  margin: 12px 0 0;
  padding-left: 18px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--muted);
}

.page-about .method-step__more li {
  margin-bottom: 8px;
}

.page-about .method-step__more li:last-child {
  margin-bottom: 0;
}

/* ---------- 版本时间线 ---------- */

.page-about .about-timeline {
  display: flex;
  gap: 14px;
  margin: 28px 0 4px;
  padding-bottom: 14px;
  overflow-x: auto;
  scroll-snap-type: x proximity;
  -webkit-overflow-scrolling: touch;
}

.page-about .tl-node {
  position: relative;
  flex: 0 0 244px;
  scroll-snap-align: start;
  padding: 26px 20px 22px;
  border-top: 2px solid var(--line);
  background-color: var(--panel);
  transition: background-color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .tl-node::before {
  content: "";
  position: absolute;
  top: -5px;
  left: 20px;
  width: 8px;
  height: 8px;
  background-color: var(--line);
  transition: background-color var(--dur) var(--ease);
}

.page-about .tl-node:hover {
  background-color: var(--panel-2);
  border-top-color: var(--cyan);
}

.page-about .tl-node:hover::before {
  background-color: var(--cyan);
}

.page-about .tl-node__ver {
  margin: 0 0 8px;
  font-size: 13px;
  letter-spacing: 0.09em;
  color: var(--cyan);
}

.page-about .tl-node h3 {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 18px;
  line-height: 1.3;
  letter-spacing: 0.01em;
}

.page-about .tl-node p:last-child {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--muted);
}

/* ---------- 团队分工 ---------- */

.page-about .team-cards {
  list-style: none;
  margin: 28px 0 0;
  padding: 0 0 28px;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
}

.page-about .team-card {
  position: relative;
  padding: 22px 20px 20px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--cyan);
  background-color: var(--panel);
  transition: background-color var(--dur) var(--ease), border-color var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.page-about .team-card:hover {
  background-color: var(--panel-2);
  border-color: var(--cyan);
}

.page-about .team-card__num {
  margin: 0 0 8px;
  font-size: 38px;
  line-height: 1;
  color: var(--cyan);
}

.page-about .team-card h3 {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 19px;
  letter-spacing: 0.01em;
}

.page-about .team-card p:last-child {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--muted);
}

/* ---------- 合作生态 ---------- */

.page-about .partner-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
  margin: 26px 0 30px;
}

.page-about .partner-card {
  padding: 22px 18px;
  border: 1px solid var(--line);
  border-top: 2px solid var(--cyan);
  background-color: var(--panel);
  transition: background-color var(--dur) var(--ease);
}

.page-about .partner-card:hover {
  background-color: var(--panel-2);
}

.page-about .partner-card h3 {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 19px;
  letter-spacing: 0.01em;
}

.page-about .partner-card p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--muted);
}

/* ---------- 纠错通道 ---------- */

.page-about .correction-panel {
  margin: 26px 0;
  border: 1px solid var(--line);
  background-color: var(--panel);
}

.page-about .correction-panel__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 4px;
  padding: 14px 18px;
  border-bottom: 1px solid var(--line);
}

.page-about .correction-panel__row:last-child {
  border-bottom: 0;
}

.page-about .correction-panel__key {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.page-about .correction-panel__val {
  font-size: 15px;
  color: var(--text);
  word-break: break-word;
}

/* ---------- 桌面布局 ---------- */

@media (min-width: 900px) {
  .page-about .about-top {
    padding-top: 156px;
  }

  .page-about .about-hero {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: 56px;
    align-items: start;
    padding-bottom: 72px;
  }

  .page-about .about-hero h1 {
    font-size: 56px;
  }

  .page-about .about-hero__intro {
    font-size: 18px;
  }

  .page-about .about-figures .stat__num {
    font-size: 34px;
  }

  .page-about .about-sect h2 {
    font-size: 40px;
  }

  .page-about .about-body {
    padding-top: 72px;
  }

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

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

  .page-about .correction-panel__row {
    grid-template-columns: 132px minmax(0, 1fr);
    align-items: baseline;
    gap: 20px;
  }
}

@media (min-width: 1040px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: 56px;
    align-items: start;
  }

  .page-about .about-rail {
    display: block;
    position: sticky;
    top: 128px;
  }

  .page-about .about-rail__inner {
    border-left: 1px solid var(--line);
    padding-left: 22px;
  }

  .page-about .about-rail__title {
    margin: 0 0 14px;
    font-size: 12px;
    letter-spacing: 0.1em;
    color: var(--muted);
  }

  .page-about .about-rail__list {
    list-style: none;
    margin: 0 0 22px;
    padding: 0;
    display: flex;
    flex-direction: column;
  }

  .page-about .about-rail__list li {
    border-bottom: 1px solid var(--hair, transparent);
  }

  .page-about .about-rail__list a {
    display: flex;
    gap: 10px;
    align-items: baseline;
    padding: 9px 0;
    font-size: 14px;
    color: var(--muted);
    text-decoration: none;
    transition: color var(--dur) var(--ease);
  }

  .page-about .about-rail__list a:hover {
    color: var(--cyan);
  }

  .page-about .about-rail__list .u-mono {
    font-size: 12px;
    color: var(--line);
    transition: color var(--dur) var(--ease);
  }

  .page-about .about-rail__list a:hover .u-mono {
    color: var(--cyan);
  }

  .page-about .about-rail__top {
    font-size: 13px;
  }

  .page-about .team-cards {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 20px;
    padding-bottom: 40px;
  }

  .page-about .team-card:nth-child(even) {
    transform: translateY(24px);
  }
}

@media (min-width: 620px) and (max-width: 1039px) {
  .page-about .team-cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .team-card:nth-child(even) {
    transform: none;
  }

  .page-about .about-figure::after {
    box-shadow: none;
  }
}

.page-about {
  --hair: currentColor;
}