/* ========================================================================
   关于页：沿用开发板页的顶栏身份块，并以数据口径组织品牌与功能说明。
   ======================================================================== */
body[data-page="about"] .topbar__identity {
  height: 48px;
  overflow: hidden;
  background: rgb(var(--glass) / .72);
  backdrop-filter: blur(10px);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  box-shadow: 0 2px 12px rgb(var(--shadow) / .12);
}
body[data-page="about"] .topbar__identity .brand {
  padding: 6px;
  background: transparent;
  backdrop-filter: none;
  border: 0;
  border-radius: 0;
  box-shadow: none;
}
body[data-page="about"] .topbar__identity .brand:hover,
body[data-page="about"] .topbar__identity .brand:focus-visible {
  background: var(--accent-soft);
}
/* 页面标题已经承担当前位置：隐藏关于入口，保留开发板入口用于返回资料库。 */
body[data-page="about"] .about-link { display: none; }

.about-context {
  display: inline-flex;
  align-items: center;
  height: 100%;
  min-width: 0;
  margin: 0;
  padding: 0 12px;
  color: var(--text);
  white-space: nowrap;
  border-left: 1px solid var(--line);
  font-size: 21px;
  line-height: 1;
  font-weight: 600;
  letter-spacing: .04em;
}

.about-main {
  padding-top: 92px;
  padding-bottom: var(--space-8);
}

.about-hero {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(360px, .75fr);
  gap: var(--space-4);
  align-items: stretch;
  padding: clamp(20px, 2.5vw, 32px);
  border: 1px solid var(--line);
  border-radius: calc(var(--radius) + 4px);
  background: var(--surface);
  box-shadow: 0 14px 38px rgb(var(--shadow) / .12);
}
.about-hero__copy {
  align-self: center;
  max-width: 720px;
}
.about-hero__copy h2 {
  max-width: 18em;
  margin-bottom: var(--space-5);
  font-size: clamp(28px, 4vw, 48px);
  line-height: 1.18;
  letter-spacing: -.035em;
}
.about-features {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-3);
  margin: 0;
  padding: 0;
  list-style: none;
}
.about-features li {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-width: 0;
  padding: var(--space-3);
  background: rgb(var(--glass) / .48);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
}
.about-features__icon {
  display: grid;
  place-items: center;
  flex: 0 0 34px;
  width: 34px;
  height: 34px;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 50%;
}
.about-features__icon svg { width: 18px; height: 18px; }
.about-features li > span:last-child {
  display: flex;
  min-width: 0;
  flex-direction: column;
  gap: 2px;
}
.about-features strong {
  font-size: var(--fs-sm);
  line-height: 1.2;
}
.about-features small {
  overflow: hidden;
  color: var(--text-muted);
  font-size: 10px;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.about-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  align-self: stretch;
  margin: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgb(var(--glass) / .48);
  overflow: hidden;
}
.about-stats > div {
  display: flex;
  flex-direction: column;
  justify-content: center;
  min-width: 0;
  padding: var(--space-5) var(--space-4);
}
.about-stats > div + div { border-left: 1px solid var(--line); }
.about-stats dt {
  color: var(--accent);
  font-size: clamp(28px, 4vw, 44px);
  font-weight: 700;
  line-height: 1;
}
.about-stats dd {
  margin: var(--space-2) 0 0;
  color: var(--text-muted);
  font-size: var(--fs-xs);
  white-space: nowrap;
}

.about-section { margin-top: clamp(32px, 4vw, 52px); }
.about-section__header {
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: var(--space-6);
  margin-bottom: var(--space-5);
}
.about-section__header h2 {
  margin: 0;
  font-size: clamp(24px, 3vw, 34px);
  letter-spacing: -.025em;
}
.about-section__header > p {
  max-width: 560px;
  margin: 0;
  color: var(--text-muted);
  font-size: var(--fs-sm);
}

.brand-grid {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: var(--space-3);
}
.brand-card {
  position: relative;
  display: flex;
  flex-direction: column;
  min-width: 0;
  padding: var(--space-3);
  color: var(--text);
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition:
    border-color .16s var(--ease),
    background-color .16s var(--ease),
    transform .12s var(--ease);
}
.brand-card:hover {
  text-decoration: none;
  border-color: var(--accent);
  background: var(--surface);
  transform: translateY(-2px);
}
.brand-card__logo {
  display: grid;
  place-items: center;
  height: 84px;
  padding: var(--space-3);
  background: #f7f7f5;
  border: 1px solid color-mix(in srgb, var(--line) 70%, #fff);
  border-radius: var(--radius-sm);
  overflow: hidden;
}
.brand-card__logo img {
  width: auto;
  max-width: 100%;
  height: auto;
  max-height: 54px;
  object-fit: contain;
}
.brand-card__meta {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2);
  min-width: 0;
  margin-top: var(--space-3);
}
.brand-card__meta strong {
  overflow: hidden;
  font-size: var(--fs-sm);
  text-overflow: ellipsis;
  white-space: nowrap;
}
.brand-card__meta > span {
  color: var(--text-muted);
  font-size: 11px;
  white-space: nowrap;
}
.brand-card__visit {
  position: absolute;
  top: var(--space-2);
  right: var(--space-2);
  padding: 2px 6px;
  color: var(--text-muted);
  background: rgb(var(--glass) / .86);
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  font-size: 9px;
  opacity: 0;
  transition: opacity .16s var(--ease);
}
.brand-card:hover .brand-card__visit,
.brand-card:focus-visible .brand-card__visit { opacity: 1; }

.about-contact {
  display: grid;
  grid-template-columns: minmax(220px, .72fr) minmax(0, 1.28fr);
  gap: clamp(24px, 5vw, 64px);
  align-items: center;
  padding: clamp(24px, 4vw, 44px);
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: calc(var(--radius) + 4px);
  box-shadow: 0 14px 38px rgb(var(--shadow) / .1);
}
.about-contact__intro h2 {
  margin: 0;
  font-size: clamp(24px, 3vw, 34px);
  letter-spacing: -.025em;
}
.about-contact__intro > p:last-child {
  max-width: 28em;
  margin: var(--space-3) 0 0;
  color: var(--text-muted);
  font-size: var(--fs-sm);
}
.about-contact__details {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
  margin: 0;
  font-style: normal;
}
.about-contact__item {
  display: flex;
  min-width: 0;
  flex-direction: column;
  gap: var(--space-2);
  padding: var(--space-4);
  background: rgb(var(--glass) / .48);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
}
.about-contact__item--address { grid-column: 1 / -1; }
.about-contact__item > span {
  color: var(--text-muted);
  font-size: var(--fs-xs);
}
.about-contact__item a,
.about-contact__item p {
  margin: 0;
  color: var(--text);
  font-size: var(--fs-sm);
  font-weight: 600;
  line-height: 1.55;
  overflow-wrap: anywhere;
}
.about-contact__item a:hover { color: var(--accent); }

@media (max-width: 980px) {
  .about-hero { grid-template-columns: 1fr; }
  .about-stats { min-height: 150px; }
  .brand-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (max-width: 640px) {
  body[data-page="about"] .topbar__identity {
    height: auto;
    overflow: visible;
    background: transparent;
    backdrop-filter: none;
    border: 0;
    border-radius: 0;
    box-shadow: none;
  }
  body[data-page="about"] .topbar__identity .brand {
    padding: 4px;
    border: 1px solid transparent;
    border-radius: var(--radius-sm);
  }
  .about-context {
    position: static;
    height: 32px;
    padding: 0 10px;
    transform: none;
    background: rgb(var(--glass) / .72);
    backdrop-filter: blur(10px);
    border: 1px solid var(--line);
    border-radius: var(--radius-pill);
    box-shadow: 0 2px 12px rgb(var(--shadow) / .12);
    font-size: 16px;
  }
  .about-main {
    padding-top: 68px;
    padding-inline: var(--space-4);
  }
  .about-hero { padding: var(--space-5); }
  .about-hero__copy h2 { font-size: 28px; }
  .about-features li {
    align-items: flex-start;
    padding: var(--space-2);
    flex-direction: column;
  }
  .about-features__icon {
    width: 30px;
    height: 30px;
    flex-basis: 30px;
  }
  .about-features small { white-space: normal; }
  .about-stats { min-height: 112px; }
  .about-stats > div { padding: var(--space-4) var(--space-2); }
  .about-stats dt { font-size: 27px; }
  .about-stats dd { font-size: 10px; }
  .about-section__header {
    display: block;
  }
  .about-section__header > p { margin-top: var(--space-3); }
  .brand-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .brand-card__logo { height: 72px; }
  .brand-card__logo img { max-height: 46px; }
  .brand-card__meta {
    align-items: start;
    flex-direction: column;
    gap: 0;
  }
  .about-contact { grid-template-columns: 1fr; }
  .about-contact__details { grid-template-columns: 1fr; }
  .about-contact__item--address { grid-column: auto; }
}

@media (max-width: 340px) {
  .about-features { grid-template-columns: 1fr; }
  .about-features li {
    align-items: center;
    flex-direction: row;
  }
  .about-features small { white-space: nowrap; }
  .about-stats dt { font-size: 22px; }
  .brand-grid { grid-template-columns: 1fr; }
}

@media (max-width: 300px) {
  /* 280px 等极窄屏：页面名替代左侧 Logo，避免与右侧三个工具按钮相撞。 */
  body[data-page="about"] .topbar__identity .brand { display: none; }
}