.page-about {
  --about-measure: 760px;
  --about-gap: 56px;
  color: var(--text);
  font-family: var(--font-sans);
  padding-bottom: 112px;
}

@media (min-width: 900px) {
  .page-about {
    padding-bottom: 160px;
  }
}

/* 面包屑 */
.page-about .breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-top: 28px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.page-about .breadcrumb a {
  color: var(--muted);
  text-decoration: none;
}

.page-about .breadcrumb a:hover {
  color: var(--lime);
}

/* 首屏框景 */
.page-about .about-hero {
  margin-top: 24px;
}

.page-about .about-hero__frame {
  position: relative;
  padding: clamp(30px, 6vw, 64px) clamp(20px, 5vw, 56px) clamp(34px, 6vw, 60px);
  border: 1px solid var(--line);
  background:
    radial-gradient(120% 150% at 100% 0%, rgba(198, 255, 61, 0.07), transparent 55%),
    linear-gradient(180deg, var(--ink-800), var(--ink-900));
  overflow: hidden;
}

.page-about .about-hero__frame::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 8px;
  background: repeating-linear-gradient(90deg, var(--line) 0 1px, transparent 1px 16px);
  opacity: 0.9;
}

.page-about .about-hero h1 {
  margin: 16px 0 22px;
  font-size: clamp(38px, 9vw, 84px);
  font-weight: 900;
  line-height: 0.96;
  letter-spacing: -0.015em;
  color: var(--text);
}

.page-about .about-hero__lede {
  max-width: 40em;
  margin: 0;
  font-size: clamp(16px, 2vw, 19px);
  line-height: 1.8;
  color: var(--text);
}

/* 图片 */
.page-about .about-figure {
  margin: 0;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  filter: saturate(0.65) contrast(1.05) brightness(0.86);
}

.page-about .about-figure--lead {
  margin-top: 28px;
  border: 1px solid var(--line);
  background: var(--ink-800);
  line-height: 0;
}

.page-about .about-figure--side {
  width: 100%;
  max-width: 340px;
  margin: 40px 0 8px;
  border: 1px solid var(--line);
  line-height: 0;
}

.page-about .about-figure--wide {
  margin: 36px 0 0;
  border: 1px solid var(--line);
  line-height: 0;
}

@media (min-width: 900px) {
  .page-about .about-figure--side {
    margin-left: auto;
    margin-right: -60px;
  }
}

/* 双栏骨架 */
.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  margin-top: 72px;
}

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

@media (min-width: 900px) {
  .page-about .about-body {
    grid-template-columns: 72px minmax(0, var(--about-measure));
    column-gap: var(--about-gap);
    margin-top: 96px;
  }
}

/* 章节竖轴 */
.page-about .about-rail {
  display: none;
}

@media (min-width: 900px) {
  .page-about .about-rail {
    display: flex;
    flex-direction: column;
    gap: 22px;
    align-self: start;
    position: sticky;
    top: calc(var(--header-h) + 48px);
    padding: 8px 0 8px 20px;
  }

  .page-about .about-rail::before {
    content: "";
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 1px;
    background: var(--line);
  }
}

.page-about .about-rail__link {
  position: relative;
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--faint);
  text-decoration: none;
}

.page-about .about-rail__link::before {
  content: "";
  position: absolute;
  left: -20px;
  top: 50%;
  width: 12px;
  height: 1px;
  background: currentColor;
  transform: translateY(-50%);
}

.page-about .about-rail__link:hover {
  color: var(--lime-deep);
}

.page-about .about-rail__link[aria-current="true"] {
  color: var(--lime);
  font-size: 17px;
}

/* 章节 */
.page-about .chapter {
  scroll-margin-top: calc(var(--header-h) + 32px);
}

.page-about .chapter + .chapter {
  margin-top: 72px;
  padding-top: 48px;
  border-top: 1px solid var(--line);
}

@media (min-width: 900px) {
  .page-about .chapter + .chapter {
    margin-top: 128px;
    padding-top: 56px;
  }
}

.page-about .chapter__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 22px;
}

.page-about .chapter__num {
  flex: none;
  padding: 3px 8px;
  border: 1px solid var(--line);
  border-radius: 2px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--lime);
}

.page-about .chapter h2 {
  margin: 0;
  font-size: clamp(24px, 4.2vw, 38px);
  font-weight: 800;
  line-height: 1.14;
  letter-spacing: -0.01em;
  color: var(--text);
}

.page-about .chapter__kicker {
  margin: 0 0 22px;
  padding-left: 14px;
  border-left: 2px solid var(--lime);
  font-size: clamp(17px, 2.4vw, 21px);
  font-weight: 700;
  line-height: 1.6;
  color: var(--text);
  max-width: 30em;
}

.page-about .chapter p {
  margin: 0 0 18px;
  max-width: 44em;
  font-size: 16px;
  line-height: 1.85;
  color: var(--text);
}

.page-about .chapter a {
  color: var(--lime);
  text-decoration: none;
  border-bottom: 1px solid rgba(198, 255, 61, 0.4);
}

.page-about .chapter a:hover {
  color: var(--lime-deep);
  border-bottom-color: var(--lime-deep);
}

/* 时间线 */
.page-about .timeline {
  position: relative;
  list-style: none;
  margin: 36px 0 32px;
  padding: 0 0 0 26px;
  max-width: 44em;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 0;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(180deg, var(--lime), var(--line) 35%, var(--line));
}

.page-about .timeline__item {
  position: relative;
  padding-bottom: 28px;
}

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

.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: -30px;
  top: 6px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--ink-900);
  border: 1px solid var(--lime);
}

.page-about .timeline__year {
  display: inline-block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--lime);
}

.page-about .timeline h3 {
  margin: 0 0 6px;
  font-size: 17px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--text);
}

.page-about .timeline p {
  margin: 0;
  max-width: none;
  font-size: 15px;
  line-height: 1.75;
  color: var(--muted);
}

/* 四步流程 */
.page-about .flow {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  list-style: none;
  margin: 32px 0 28px;
  padding: 0;
  background: var(--line);
  border: 1px solid var(--line);
}

@media (min-width: 720px) {
  .page-about .flow {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .flow__step {
  position: relative;
  padding: 20px 22px 22px 18px;
  background: var(--panel);
}

.page-about .flow__idx {
  display: block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--faint);
}

.page-about .flow__step h3 {
  margin: 0 0 8px;
  font-size: 15px;
  font-weight: 700;
  line-height: 1.4;
  color: var(--text);
}

.page-about .flow__step p {
  margin: 0;
  max-width: none;
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
}

.page-about .flow__role {
  display: inline-block;
  margin-top: 12px;
  padding: 2px 7px;
  border: 1px solid var(--line);
  border-radius: 2px;
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--lime);
}

.page-about .flow__arrow {
  display: none;
  position: absolute;
  top: 50%;
  right: 6px;
  width: 14px;
  height: 14px;
  color: var(--faint);
  transform: translateY(-50%);
}

@media (min-width: 720px) {
  .page-about .flow__arrow {
    display: block;
  }

  .page-about .flow__step:last-child .flow__arrow {
    display: none;
  }
}

/* 记录构成表 */
.page-about .record {
  margin: 32px 0 28px;
  max-width: 44em;
  border-top: 1px solid var(--line);
}

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

@media (min-width: 640px) {
  .page-about .record__row {
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 20px;
    align-items: baseline;
  }
}

.page-about .record__row dt {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 700;
  color: var(--text);
}

.page-about .record__row dt::before {
  content: "";
  flex: none;
  width: 4px;
  height: 4px;
  background: var(--lime);
}

.page-about .record__row--score dt::before {
  background: var(--amber);
}

.page-about .record__row dd {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--muted);
}

/* 使用场景 */
.page-about .uses {
  margin: 32px 0 8px;
  max-width: 44em;
}

.page-about .uses__item {
  margin-bottom: 30px;
}

.page-about .uses__item h3 {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin: 0 0 8px;
  font-size: 17px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--text);
}

.page-about .uses__num {
  flex: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--lime);
}

.page-about .uses__item p {
  margin: 0;
  max-width: none;
  font-size: 15px;
  line-height: 1.8;
  color: var(--muted);
}

/* 问答 */
.page-about .qa {
  margin: 28px 0 0;
  border-top: 1px solid var(--line);
  max-width: 44em;
}

.page-about .qa__item {
  border-bottom: 1px solid var(--line);
}

.page-about .qa__item summary {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 18px 0;
  list-style: none;
  cursor: pointer;
  font-size: 16px;
  font-weight: 700;
  line-height: 1.55;
  color: var(--text);
}

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

.page-about .qa__item summary:hover {
  color: var(--lime);
}

.page-about .qa__q-num {
  flex: none;
  padding-top: 3px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--lime);
}

.page-about .qa__icon {
  flex: none;
  margin-left: auto;
  width: 16px;
  height: 16px;
  margin-top: 4px;
  color: var(--faint);
}

.page-about .qa__item[open] .qa__icon {
  color: var(--lime);
  transform: rotate(180deg);
}

.page-about .qa__body {
  padding: 0 0 20px 30px;
}

.page-about .qa__body p {
  margin: 0 0 10px;
  max-width: none;
  font-size: 15px;
  line-height: 1.8;
  color: var(--muted);
}

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

/* 渠道说明 */
.page-about .about-channel {
  margin: 64px 0 0;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  max-width: 44em;
  font-size: 14px;
  line-height: 1.85;
  color: var(--muted);
}

/* 焦点样式 */
.page-about a:focus-visible,
.page-about summary:focus-visible {
  outline: 2px solid var(--lime);
  outline-offset: 2px;
}

/* 动效 */
@media (prefers-reduced-motion: no-preference) {
  .page-about .about-rail__link {
    transition: color 180ms var(--ease), font-size 180ms var(--ease);
  }

  .page-about .chapter a,
  .page-about .breadcrumb a {
    transition: color 160ms var(--ease), border-color 160ms var(--ease);
  }

  .page-about .qa__icon {
    transition: transform 220ms var(--ease), color 160ms var(--ease);
  }
}