.page-about {
  --ab-on-paper-2: #5A5145;
  --ab-hair-paper: rgba(21, 19, 15, 0.13);
  background: var(--df-ink-900);
}

.page-about .ab-crumb {
  padding-block: 20px 4px;
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  position: relative;
  overflow: hidden;
  padding-block: 34px 62px;
  background:
    radial-gradient(120% 100% at 88% 0%, rgba(198, 161, 91, 0.11), transparent 60%),
    radial-gradient(80% 70% at 4% 100%, rgba(180, 85, 46, 0.07), transparent 62%),
    var(--df-ink-900);
}

.page-about .ab-hero__title {
  margin: 18px 0 0;
  max-width: 22ch;
  font-family: var(--df-font-cn);
  font-size: clamp(2rem, 5.2vw, 4rem);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--df-ivory-050);
}

.page-about .ab-hero__lower {
  margin-top: 34px;
  padding-top: 28px;
  border-top: 1px solid var(--df-line-700);
  display: grid;
  gap: 28px;
}

.page-about .ab-hero__lede {
  margin: 0;
  max-width: 60ch;
  font-size: 15px;
  line-height: 1.92;
  letter-spacing: 0.01em;
  color: var(--df-ivory-mute);
}

.page-about .ab-stats {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px 22px;
}

.page-about .ab-stat {
  padding-top: 12px;
  border-top: 1px solid var(--df-gold-line);
}

.page-about .ab-stat__num {
  display: block;
  font-family: var(--df-font-num);
  font-size: 25px;
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: 0.01em;
  font-variant-numeric: tabular-nums;
  color: var(--df-amber-400);
}

.page-about .ab-stat__label {
  display: block;
  margin-top: 5px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--df-gray-500);
}

@media (min-width: 880px) {
  .page-about .ab-hero {
    padding-block: 44px 76px;
  }
  .page-about .ab-hero__lower {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
    gap: 64px;
    align-items: start;
  }
  .page-about .ab-stats {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 24px 26px;
  }
}

/* ---------- 主体 4:8 ---------- */
.page-about .ab-main {
  padding-block: 52px 84px;
  background: linear-gradient(180deg, var(--df-ink-900) 0%, var(--df-ink-800) 100%);
}

.page-about .ab-main__grid {
  display: grid;
  gap: 30px;
}

/* 左侧刻度栏 */
.page-about .ab-rail__kicker {
  margin: 0 0 16px;
  font-family: var(--df-font-num);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--df-gold-500);
}

.page-about .ab-scale {
  list-style: none;
  margin: 0;
  padding: 0 0 0 20px;
  border-left: 1px solid var(--df-line-700);
}

.page-about .ab-scale__item + .ab-scale__item {
  margin-top: 2px;
}

.page-about .ab-scale__link {
  position: relative;
  display: block;
  padding: 9px 0 9px 14px;
  text-decoration: none;
  color: inherit;
}

.page-about .ab-scale__link::before {
  content: "";
  position: absolute;
  left: -24px;
  top: 16px;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--df-line-700);
  transition: background 180ms var(--df-ease), transform 180ms var(--df-ease);
}

.page-about .ab-scale__link:hover::before,
.page-about .ab-scale__link:focus-visible::before {
  background: var(--df-amber-400);
  transform: scale(1.4);
}

.page-about .ab-scale__link:focus-visible {
  outline: 2px solid var(--df-amber-400);
  outline-offset: 2px;
}

.page-about .ab-scale__year {
  display: block;
  font-family: var(--df-font-num);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
  color: var(--df-ivory-050);
  transition: color 180ms var(--df-ease);
}

.page-about .ab-scale__link:hover .ab-scale__year {
  color: var(--df-amber-400);
}

.page-about .ab-scale__text {
  display: block;
  margin-top: 3px;
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--df-gray-500);
}

@media (max-width: 1023px) {
  .page-about .ab-scale {
    display: flex;
    gap: 8px;
    overflow-x: auto;
    padding: 0 0 8px;
    border-left: 0;
    -webkit-overflow-scrolling: touch;
  }
  .page-about .ab-scale__item + .ab-scale__item {
    margin-top: 0;
  }
  .page-about .ab-scale__link {
    padding: 9px 14px;
    border: 1px solid var(--df-line-700);
    white-space: nowrap;
  }
  .page-about .ab-scale__link::before {
    display: none;
  }
}

@media (min-width: 1024px) {
  .page-about .ab-main__grid {
    grid-template-columns: minmax(0, 3.6fr) minmax(0, 8.4fr);
    gap: 48px;
    align-items: start;
  }
  .page-about .ab-rail {
    position: sticky;
    top: calc(var(--df-header-h) + 30px);
  }
}

/* 右侧纸本内容区 */
.page-about .ab-flow {
  background: var(--df-cream-100);
  color: var(--df-ink-on-paper);
  padding: 34px 22px 44px;
  border: 1px solid rgba(244, 239, 230, 0.07);
  box-shadow: var(--df-shadow-1);
}

@media (min-width: 720px) {
  .page-about .ab-flow {
    padding: 54px 52px 62px;
  }
}

.page-about .ab-section + .ab-section {
  margin-top: 54px;
  padding-top: 50px;
  border-top: 1px solid var(--ab-hair-paper);
}

.page-about .ab-section__head {
  margin-bottom: 20px;
}

.page-about .ab-section__idx {
  margin: 0 0 10px;
  font-family: var(--df-font-num);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.16em;
  font-variant-numeric: tabular-nums;
  color: var(--df-orange-600);
}

.page-about .ab-section__title {
  margin: 0;
  font-family: var(--df-font-cn);
  font-size: clamp(1.3rem, 2.5vw, 1.8rem);
  font-weight: 800;
  line-height: 1.3;
  letter-spacing: -0.01em;
  color: var(--df-ink-on-paper);
}

.page-about .ab-section__lede {
  margin: 0 0 22px;
  max-width: 64ch;
  font-size: 15px;
  line-height: 1.92;
  letter-spacing: 0.01em;
  color: var(--ab-on-paper-2);
}

.page-about .ab-section__lede:last-of-type {
  margin-bottom: 0;
}

/* 受众列表 */
.page-about .ab-audience {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .ab-audience__item {
  display: grid;
  grid-template-columns: 30px minmax(0, 1fr);
  gap: 14px;
  padding: 18px 0;
  border-top: 1px solid var(--ab-hair-paper);
}

.page-about .ab-audience__item:last-child {
  border-bottom: 1px solid var(--ab-hair-paper);
}

.page-about .ab-audience__num {
  padding-top: 3px;
  font-family: var(--df-font-num);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--df-orange-600);
}

.page-about .ab-audience__title {
  margin: 0 0 6px;
  font-size: 15.5px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--df-ink-on-paper);
}

.page-about .ab-audience__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.88;
  color: var(--ab-on-paper-2);
}

/* 旁注 */
.page-about .ab-aside {
  margin-top: 26px;
  padding: 20px 22px;
  background: var(--df-brown-850);
  border-left: 3px solid var(--df-gold-500);
}

.page-about .ab-aside__k {
  margin: 0 0 12px;
  font-family: var(--df-font-num);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--df-amber-400);
}

.page-about .ab-aside__list {
  margin: 0;
  padding-left: 18px;
  list-style: decimal;
  font-size: 13.5px;
  line-height: 1.95;
  color: var(--df-ivory-mute);
}

.page-about .ab-aside__list li::marker {
  color: var(--df-metal-300);
  font-family: var(--df-font-num);
}

/* 年份时间线 */
.page-about .ab-year {
  list-style: none;
  margin: 6px 0 0;
  padding: 0;
}

.page-about .ab-year__item {
  display: grid;
  gap: 6px;
  padding: 26px 0;
  border-top: 1px solid var(--ab-hair-paper);
  scroll-margin-top: calc(var(--df-header-h) + 28px);
}

.page-about .ab-year__item:last-child {
  border-bottom: 1px solid var(--ab-hair-paper);
}

.page-about .ab-year__big {
  margin: 0;
  font-family: var(--df-font-num);
  font-size: clamp(2.2rem, 4.6vw, 3.4rem);
  font-weight: 200;
  line-height: 0.9;
  letter-spacing: -0.04em;
  font-variant-numeric: tabular-nums;
  color: rgba(30, 23, 18, 0.18);
  user-select: none;
}

.page-about .ab-year__title {
  margin: 0 0 8px;
  font-family: var(--df-font-cn);
  font-size: 16.5px;
  font-weight: 800;
  line-height: 1.45;
  color: var(--df-ink-on-paper);
}

.page-about .ab-year__text {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.9;
  color: var(--ab-on-paper-2);
}

@media (min-width: 720px) {
  .page-about .ab-year__item {
    grid-template-columns: 134px minmax(0, 1fr);
    gap: 26px;
    align-items: start;
    padding: 30px 0;
  }
  .page-about .ab-year__big {
    padding-top: 2px;
  }
}

/* 图片 */
.page-about .ab-figure {
  margin: 30px 0 0;
}

.page-about .ab-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: 1px;
  filter: saturate(0.9) contrast(1.02);
  background: linear-gradient(150deg, var(--df-brown-850), var(--df-ink-800));
}

.page-about .ab-figure figcaption {
  margin-top: 11px;
  padding-left: 12px;
  border-left: 2px solid var(--df-gold-500);
  font-size: 12.5px;
  line-height: 1.75;
  color: var(--df-metal-300);
}

/* 团队 */
.page-about .ab-teams {
  margin-bottom: 24px;
}

.page-about .ab-team {
  padding: 17px 0;
  border-top: 1px solid var(--ab-hair-paper);
}

.page-about .ab-team:last-child {
  border-bottom: 1px solid var(--ab-hair-paper);
}

.page-about .ab-team__title {
  margin: 0 0 5px;
  font-size: 15px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--df-ink-on-paper);
}

.page-about .ab-team__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.88;
  color: var(--ab-on-paper-2);
}

/* 三层体系 */
.page-about .ab-layers {
  margin-bottom: 28px;
  border-top: 1px solid var(--ab-hair-paper);
}

.page-about .ab-layer {
  display: grid;
  gap: 6px;
  padding: 17px 0;
  border-bottom: 1px solid var(--ab-hair-paper);
}

.page-about .ab-layer__tag {
  font-family: var(--df-font-num);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--df-orange-600);
}

.page-about .ab-layer__title {
  margin: 0;
  font-size: 15px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--df-ink-on-paper);
}

.page-about .ab-layer__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.88;
  color: var(--ab-on-paper-2);
}

@media (min-width: 700px) {
  .page-about .ab-layer {
    grid-template-columns: 92px 210px minmax(0, 1fr);
    gap: 22px;
    align-items: baseline;
  }
  .page-about .ab-layer__tag {
    padding-top: 3px;
  }
}

/* 编号说明块 */
.page-about .ab-code {
  margin: 0 0 26px;
  padding: 22px 24px;
  background: var(--df-brown-850);
  border-left: 3px solid var(--df-gold-500);
}

.page-about .ab-code__label {
  margin: 0 0 14px;
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--df-gray-500);
}

.page-about .ab-code__sample {
  margin: 0 0 14px;
  font-family: var(--df-font-num);
  font-size: clamp(1.5rem, 4.2vw, 2.1rem);
  font-weight: 300;
  letter-spacing: 0.06em;
  font-variant-numeric: tabular-nums;
  color: var(--df-amber-400);
}

.page-about .ab-code__seg {
  position: relative;
  padding: 0 2px;
}

.page-about .ab-code__seg::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -4px;
  height: 1px;
  background: rgba(224, 185, 106, 0.35);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 260ms var(--df-ease);
}

.page-about .ab-code__sample:hover .ab-code__seg::after {
  transform: scaleX(1);
}

.page-about .ab-code__dash {
  color: var(--df-metal-300);
}

.page-about .ab-code__note {
  margin: 0;
  font-size: 13px;
  line-height: 1.85;
  color: var(--df-ivory-mute);
}

/* 季度数字 */
.page-about .ab-quarter {
  display: flex;
  flex-wrap: wrap;
  gap: 16px 36px;
  margin-bottom: 24px;
  padding: 18px 0 20px;
  border-top: 1px solid var(--ab-hair-paper);
  border-bottom: 1px solid var(--ab-hair-paper);
}

.page-about .ab-quarter__num {
  display: block;
  font-family: var(--df-font-num);
  font-size: 29px;
  font-weight: 500;
  line-height: 1.1;
  font-variant-numeric: tabular-nums;
  color: var(--df-orange-600);
}

.page-about .ab-quarter__txt {
  display: block;
  margin-top: 5px;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--df-metal-300);
}

/* 合作方 */
.page-about .ab-partner {
  list-style: none;
  margin: 0 0 24px;
  padding: 0;
}

.page-about .ab-partner__item {
  position: relative;
  padding: 17px 0 17px 22px;
  border-top: 1px solid var(--ab-hair-paper);
}

.page-about .ab-partner__item:last-child {
  border-bottom: 1px solid var(--ab-hair-paper);
}

.page-about .ab-partner__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 27px;
  width: 9px;
  height: 1px;
  background: var(--df-orange-600);
}

.page-about .ab-partner__title {
  margin: 0 0 5px;
  font-size: 15px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--df-ink-on-paper);
}

.page-about .ab-partner__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.88;
  color: var(--ab-on-paper-2);
}

/* 行动按钮（纸底适配） */
.page-about .ab-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 26px 0 0;
}

.page-about .ab-flow .df-btn--ghost,
.page-about .ab-flow .df-btn--line {
  color: var(--df-ink-on-paper);
  border-color: rgba(21, 19, 15, 0.28);
  background: transparent;
}

.page-about .ab-flow .df-btn--ghost:hover,
.page-about .ab-flow .df-btn--line:hover {
  color: var(--df-brown-850);
  border-color: var(--df-orange-600);
}

.page-about .ab-flow .df-btn:focus-visible {
  outline: 2px solid var(--df-orange-600);
  outline-offset: 2px;
}

/* 滚动显现 */
.page-about [data-reveal] {
  opacity: 1;
}

@media (prefers-reduced-motion: no-preference) {
  .page-about [data-reveal] {
    opacity: 0;
    transform: translateY(8px);
    transition: opacity 320ms var(--df-ease), transform 320ms var(--df-ease);
  }
  .page-about [data-reveal="in"] {
    opacity: 1;
    transform: none;
  }
}
</main>