.page-about {
  background: var(--phx-bg);
  color: var(--phx-ink);
  font-family: var(--font-body);
  line-height: var(--lh-body);
  overflow-x: hidden;
}

.page-about [id] {
  scroll-margin-top: calc(var(--header-h) + 20px);
}

.page-about a {
  color: var(--phx-blue-deep);
  text-decoration: underline;
  text-decoration-color: var(--phx-gold);
  text-underline-offset: 4px;
}

/* ===== 品牌简介 / Intro ===== */
.page-about__intro {
  padding: 56px 0 72px;
  border-bottom: 1px solid var(--phx-line);
}

.page-about__intro-grid {
  display: grid;
  gap: 40px;
}

.page-about__intro-copy .crumb-nav {
  margin-bottom: 24px;
}

.page-about__intro-copy h1 {
  font-family: var(--font-head);
  font-size: var(--fs-h1);
  line-height: var(--lh-head);
  color: var(--phx-blue-deep);
  margin: 12px 0 16px;
}

.page-about__intro-lead {
  font-size: 18px;
  line-height: 1.8;
  color: var(--phx-blue-deep);
  border-left: 4px solid var(--phx-gold);
  padding-left: 16px;
}

.page-about__intro-title {
  font-family: var(--font-head);
  font-size: var(--fs-h2);
  line-height: 1.24;
  color: var(--phx-blue-deep);
  margin: 56px 0 12px;
}

.page-about__intro-copy p + p {
  margin-top: 12px;
}

.page-about__value-list {
  list-style: none;
  margin: 32px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about__value-list li {
  display: grid;
  grid-template-columns: 96px 1fr;
  gap: 14px;
  background: var(--phx-white);
  border-left: 3px solid var(--phx-gold);
  padding: 14px 16px;
  align-items: baseline;
}

.page-about__value-code {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .04em;
  color: var(--phx-orange);
}

.page-about__value-list strong {
  display: block;
  color: var(--phx-blue-deep);
  font-size: 16px;
  margin-bottom: 2px;
}

.page-about__value-list li div span {
  font-size: 14px;
  color: var(--phx-ink);
  opacity: .78;
  display: block;
}

.page-about__intro-media {
  max-width: 600px;
}

.page-about__img-frame {
  position: relative;
  border: 1px solid var(--phx-line);
  background:
    linear-gradient(var(--phx-line) 1px, transparent 1px) 0 0 / 100% 24px,
    var(--phx-white);
  padding: 12px;
}

.page-about__img-frame img {
  width: 100%;
  height: auto;
  display: block;
}

.page-about__img-frame::after {
  content: "";
  position: absolute;
  right: -14px;
  bottom: -14px;
  width: 88px;
  height: 88px;
  border-right: 4px solid var(--phx-gold);
  border-bottom: 4px solid var(--phx-gold);
  pointer-events: none;
}

.page-about__media-cap {
  margin-top: 20px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--phx-orange);
  text-transform: uppercase;
}

/* ===== 连续画布 / 目录索引 ===== */
.page-about__canvas {
  padding: 72px 0 96px;
  display: grid;
  gap: 40px;
}

.page-about__index {
  background: var(--phx-white);
  border: 1px solid var(--phx-line);
  padding: 20px;
}

.page-about__index-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--phx-purple);
  margin-bottom: 14px;
}

.page-about__index a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 9px 0;
  color: var(--phx-blue-deep);
  text-decoration: none;
  font-size: 15px;
  border-bottom: 1px solid var(--phx-line);
}

.page-about__index a:last-child {
  border-bottom: 0;
}

.page-about__index a span {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--phx-orange);
  min-width: 24px;
}

.page-about__content {
  min-width: 0;
}

/* ===== 章节基础 ===== */
.page-about__section {
  margin-bottom: 72px;
}

.page-about__section:last-child {
  margin-bottom: 0;
}

.page-about__section--dark {
  background:
    linear-gradient(rgba(255, 255, 255, .04) 1px, transparent 1px) 0 0 / 100% 48px,
    var(--phx-blue-deep);
  border-top: 3px solid var(--phx-gold);
  padding: 36px 24px 44px;
  color: rgba(255, 255, 255, .78);
}

.page-about__section--dark a {
  color: var(--phx-gold);
}

.page-about__section-head h2 {
  font-family: var(--font-head);
  font-size: var(--fs-h2);
  line-height: 1.24;
  color: var(--phx-blue-deep);
  margin: 10px 0 14px;
}

.page-about__section--dark .page-about__section-head h2 {
  color: var(--phx-white);
}

.page-about__section-head p {
  color: var(--phx-ink);
  opacity: .78;
  max-width: 640px;
}

.page-about__section--dark .page-about__section-head p {
  color: rgba(255, 255, 255, .72);
  opacity: 1;
}

/* ===== 发展历程 ===== */
.page-about__milestone-wrap {
  display: grid;
  gap: 32px;
  margin: 36px 0 20px;
}

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

.page-about__timeline-item {
  border-top: 1px solid var(--phx-line-dark);
}

.page-about__timeline-item:first-child {
  border-top: 0;
}

.page-about__timeline details {
  padding: 0;
}

.page-about__timeline summary {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about__timeline summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 20px;
  color: var(--phx-orange);
  transition: transform .3s var(--ease);
}

.page-about__timeline details[open] summary::after {
  content: "–";
}

.page-about__tl-code {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 16px;
  color: var(--phx-gold);
  min-width: 36px;
}

.page-about__tl-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--phx-white);
}

.page-about__timeline details p {
  margin: 0;
  padding: 0 0 20px;
  max-width: 560px;
  font-size: 15px;
  color: rgba(255, 255, 255, .68);
}

.page-about__milestone-media img,
.page-about__data-media img {
  width: 100%;
  height: auto;
  display: block;
  border: 1px solid var(--phx-line-dark);
}

.page-about__milestone-media figcaption,
.page-about__data-media figcaption {
  margin-top: 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--phx-orange);
}

.page-about__timeline-closing {
  font-size: 14px;
  color: rgba(255, 255, 255, .62);
}

/* ===== 数据能力 ===== */
.page-about__data-layout {
  display: grid;
  gap: 32px;
  margin: 36px 0 20px;
}

.page-about__data-stats {
  display: grid;
  gap: 12px;
}

.page-about__stat {
  background: var(--phx-white);
  border-left: 4px solid var(--phx-cyan);
  padding: 18px 20px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  box-shadow: 0 1px 0 var(--phx-line);
}

.page-about__stat-num {
  font-family: var(--font-mono);
  font-size: 28px;
  font-weight: 700;
  color: var(--phx-blue-deep);
  line-height: 1.1;
}

.page-about__stat-label {
  font-size: 14px;
  color: var(--phx-ink);
  opacity: .72;
}

.page-about__data-closing {
  font-size: 15px;
  color: var(--phx-ink);
  opacity: .82;
}

/* ===== 合作与生态 ===== */
.page-about__eco-grid {
  margin-top: 36px;
}

.page-about__eco-card {
  background: var(--phx-white);
  border-top: 3px solid var(--phx-gold);
  padding: 28px 24px 30px;
}

.page-about__eco-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 30px;
  font-weight: 700;
  color: var(--phx-orange);
}

.page-about__eco-card h3 {
  font-family: var(--font-head);
  font-size: var(--fs-h3);
  line-height: 1.28;
  color: var(--phx-blue-deep);
  margin: 10px 0 10px;
}

.page-about__eco-card p {
  margin: 0;
  font-size: 15px;
  color: var(--phx-ink);
  opacity: .8;
}

.page-about__eco-closing {
  margin-top: 28px;
  font-size: 15px;
  color: var(--phx-ink);
  opacity: .8;
  border-left: 3px solid var(--phx-green);
  padding-left: 14px;
}

/* ===== 资质与荣誉 ===== */
.page-about__honor-grid {
  list-style: none;
  margin: 36px 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about__honor-card {
  background: var(--phx-white);
  border-left: 3px solid var(--phx-green);
  padding: 24px 20px;
  display: grid;
  grid-template-columns: 48px 1fr;
  gap: 16px;
  align-items: start;
}

.page-about__honor-icon {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--phx-blue-deep);
  color: var(--phx-gold);
  font-family: var(--font-mono);
  font-size: 18px;
}

.page-about__honor-card h3 {
  font-family: var(--font-head);
  font-size: 18px;
  line-height: 1.3;
  color: var(--phx-blue-deep);
  margin: 0 0 6px;
}

.page-about__honor-card p {
  margin: 0;
  font-size: 14px;
  color: var(--phx-ink);
  opacity: .78;
}

/* ===== 桌面布局（移动端优先） ===== */
@media (min-width: 900px) {
  .page-about__intro {
    padding: 96px 0 112px;
  }

  .page-about__intro-grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
    align-items: center;
  }

  .page-about__value-list {
    grid-template-columns: 1fr 1fr;
  }

  .page-about__canvas {
    grid-template-columns: 220px minmax(0, 1fr);
    align-items: start;
    gap: 56px;
  }

  .page-about__index {
    position: sticky;
    top: calc(var(--header-h) + 24px);
  }

  .page-about__section {
    margin-bottom: 96px;
  }

  .page-about__section--dark {
    padding: 52px 40px 56px;
  }

  .page-about__milestone-wrap {
    grid-template-columns: minmax(0, 1fr) minmax(300px, 420px);
    align-items: start;
    gap: 48px;
  }

  .page-about__timeline details p {
    padding-left: 50px;
  }

  .page-about__data-layout {
    grid-template-columns: minmax(0, 1fr) minmax(320px, 1.05fr);
    align-items: center;
    gap: 48px;
  }

  .page-about__data-stats {
    grid-template-columns: 1fr 1fr;
    gap: 16px;
  }

  .page-about__honor-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}