.page-about {
  --about-rail: 196px;
  --about-gap: clamp(24px, 4vw, 56px);
  background-color: var(--paper-cream);
  color: var(--body-ink);
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumb {
  padding-top: clamp(14px, 2.2vw, 24px);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  border-bottom: var(--hairline);
  background-color: var(--paper-cream);
}

.page-about .about-hero__wash {
  position: absolute;
  top: -18%;
  right: -14%;
  width: min(62%, 760px);
  height: 136%;
  background-color: var(--glacier-mist);
  transform: skewX(-7deg);
  z-index: 0;
}

.page-about .about-hero__grid-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  background-image:
    repeating-linear-gradient(to right, var(--grid-line) 0 1px, transparent 1px 48px),
    repeating-linear-gradient(to bottom, var(--grid-line) 0 1px, transparent 1px 48px);
  opacity: .35;
  pointer-events: none;
}

.page-about .about-hero__grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 4vw, 40px);
  padding-top: clamp(30px, 5vw, 68px);
  padding-bottom: clamp(32px, 5vw, 76px);
}

.page-about .about-hero__kicker {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: .16em;
  color: var(--glacier-blue);
  margin: 0 0 14px;
}

.page-about .about-hero__title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: var(--fs-display);
  line-height: 1.16;
  letter-spacing: -.01em;
  color: var(--glacier-ink);
  margin: 0 0 clamp(16px, 2.4vw, 24px);
  max-width: 18em;
}

.page-about .about-hero__lead {
  font-size: var(--fs-body);
  line-height: 1.85;
  color: var(--body-ink);
  max-width: 40em;
  margin: 0;
}

.page-about .about-hero__facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1px;
  background-color: var(--grid-line);
  border: var(--hairline);
  margin-top: clamp(24px, 3.4vw, 40px);
  max-width: 660px;
}

.page-about .about-fact {
  background-color: var(--snow-white);
  padding: 14px 16px 16px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.page-about .about-fact__k {
  font-family: var(--font-mono);
  font-size: var(--fs-micro);
  letter-spacing: .14em;
  color: var(--glacier-blue);
  text-transform: uppercase;
}

.page-about .about-fact__v {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(26px, 3vw, 34px);
  line-height: 1.1;
  color: var(--glacier-ink);
}

.page-about .about-fact__u {
  font-size: var(--fs-xs);
  line-height: 1.6;
  color: var(--glacier-deep);
}

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

/* ---------- 主体骨架 ---------- */
.page-about .about-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(26px, 4vw, 48px);
  padding-top: clamp(30px, 4.6vw, 62px);
  padding-bottom: clamp(44px, 6vw, 92px);
}

/* ---------- 章节索引栏 ---------- */
.page-about .index-rail {
  position: sticky;
  top: 70px;
  align-self: start;
  z-index: 3;
  display: flex;
  flex-direction: row;
  gap: 2px;
  overflow-x: auto;
  padding: 0 0 8px;
  border-bottom: var(--hairline);
  background-color: var(--paper-cream);
  scrollbar-width: none;
}

.page-about .index-rail::-webkit-scrollbar {
  display: none;
}

.page-about .index-rail__link {
  position: relative;
  display: block;
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: .08em;
  color: var(--glacier-deep);
  text-decoration: none;
  padding: 8px 12px 8px 12px;
  border-left: 2px solid transparent;
  white-space: nowrap;
  transition: color .15s ease, border-color .15s ease, transform .15s ease, background-color .15s ease;
}

.page-about .index-rail__link:hover,
.page-about .index-rail__link:focus-visible {
  color: var(--glacier-blue);
  background-color: var(--glacier-mist);
}

.page-about .index-rail__link[aria-current="true"] {
  color: var(--maple-red);
  border-left-color: var(--maple-red);
  background-color: var(--snow-white);
  transform: translateX(2px);
}

/* ---------- 章节通用 ---------- */
.page-about .about-sec + .about-sec {
  margin-top: clamp(34px, 5vw, 66px);
  padding-top: clamp(28px, 4vw, 54px);
  border-top: var(--hairline);
}

.page-about .about-sec__head {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: clamp(12px, 1.8vw, 20px);
}

.page-about .about-sec__no {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  font-weight: 500;
  letter-spacing: .12em;
  color: var(--maple-red);
  flex: 0 0 auto;
}

.page-about .about-sec__head .t-title {
  margin: 0;
}

.page-about .about-sec__lead {
  margin: 0 0 clamp(16px, 2.4vw, 26px);
  max-width: 42em;
}

.page-about .about-prose p {
  font-size: var(--fs-body);
  line-height: 1.85;
  color: var(--body-ink);
  max-width: 44em;
  margin: 0 0 1em;
}

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

/* ---------- 时间轴 ---------- */
.page-about .about-tl-frame {
  margin: clamp(22px, 3.2vw, 36px) 0 clamp(20px, 3vw, 32px);
  border: var(--hairline);
  background-color: var(--glacier-ink);
  aspect-ratio: 8 / 3;
  overflow: hidden;
}

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

.page-about .about-tl {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}

.page-about .about-tl::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 10px;
  bottom: 12px;
  width: 1px;
  background-color: var(--grid-line);
}

.page-about .about-tl__item {
  position: relative;
  padding-left: 30px;
  border-bottom: var(--hairline);
}

.page-about .about-tl__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 19px;
  width: 11px;
  height: 11px;
  box-sizing: border-box;
  background-color: var(--snow-white);
  border: 1px solid var(--glacier-blue);
  transition: background-color .2s ease, border-color .2s ease;
}

.page-about .about-tl__item:has(details[open])::before {
  background-color: var(--maple-red);
  border-color: var(--maple-red);
}

.page-about .about-tl__sum {
  display: grid;
  grid-template-columns: 62px minmax(0, 1fr) 18px;
  align-items: center;
  gap: 10px;
  padding: 16px 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-tl__sum:focus-visible {
  outline: 2px solid var(--maple-red);
  outline-offset: 2px;
}

.page-about .about-tl__year {
  font-family: var(--font-mono);
  font-size: var(--fs-sm);
  font-weight: 500;
  letter-spacing: .04em;
  color: var(--glacier-blue);
}

.page-about .about-tl__head {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--fs-md);
  line-height: 1.35;
  color: var(--glacier-ink);
}

.page-about .about-tl__mark {
  position: relative;
  justify-self: end;
  width: 14px;
  height: 14px;
}

.page-about .about-tl__mark::before,
.page-about .about-tl__mark::after {
  content: "";
  position: absolute;
  background-color: var(--maple-red);
}

.page-about .about-tl__mark::before {
  left: 0;
  right: 0;
  top: 6px;
  height: 1px;
}

.page-about .about-tl__mark::after {
  top: 0;
  bottom: 0;
  left: 6px;
  width: 1px;
}

.page-about .about-tl__node[open] .about-tl__mark::after {
  display: none;
}

.page-about .about-tl__body {
  padding: 0 0 18px;
}

.page-about .about-tl__body p {
  margin: 0 0 .7em;
  font-size: var(--fs-sm);
  line-height: 1.82;
  color: var(--body-ink);
  max-width: 42em;
}

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

/* ---------- 三次改版 ---------- */
.page-about .about-rev-fig {
  margin: 0 0 clamp(18px, 2.6vw, 28px);
  border: var(--hairline);
  background-color: var(--glacier-mist);
}

.page-about .about-rev-fig img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
}

.page-about .about-rev {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background-color: var(--grid-line);
  border: var(--hairline);
}

.page-about .about-rev__item {
  background-color: var(--snow-white);
  padding: clamp(18px, 2.4vw, 28px);
  display: flex;
  flex-direction: column;
}

.page-about .about-rev__no {
  font-family: var(--font-mono);
  font-size: var(--fs-micro);
  letter-spacing: .16em;
  color: var(--maple-red);
  display: block;
  margin-bottom: 10px;
}

.page-about .about-rev__t {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: var(--fs-sub);
  line-height: 1.25;
  color: var(--glacier-ink);
  margin: 0 0 12px;
}

.page-about .about-rev__p {
  margin: 0 0 14px;
  font-size: var(--fs-sm);
  line-height: 1.82;
  color: var(--body-ink);
}

.page-about .about-rev__fix {
  margin: auto 0 0;
  padding-top: 12px;
  border-top: var(--hairline);
  font-size: var(--fs-sm);
  line-height: 1.8;
  color: var(--glacier-deep);
}

/* ---------- 人群卡片 ---------- */
.page-about .about-aud {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background-color: var(--grid-line);
  border: var(--hairline);
}

.page-about .about-aud__card {
  background-color: var(--snow-white);
  padding: clamp(18px, 2.4vw, 26px);
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.page-about .about-aud__no {
  font-family: var(--font-mono);
  font-size: var(--fs-micro);
  letter-spacing: .14em;
  color: var(--glacier-blue);
}

.page-about .about-aud__who {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--fs-md);
  line-height: 1.35;
  color: var(--glacier-ink);
  margin: 0;
}

.page-about .about-aud__p {
  margin: 0;
  font-size: var(--fs-sm);
  line-height: 1.82;
  color: var(--body-ink);
}

.page-about .about-aud__link {
  margin-top: auto;
  align-self: flex-start;
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: .06em;
  color: var(--maple-red);
  text-decoration: none;
  padding-bottom: 2px;
  border-bottom: 1px solid var(--maple-red);
  transition: color .15s ease, border-color .15s ease;
}

.page-about .about-aud__link:hover,
.page-about .about-aud__link:focus-visible {
  color: var(--glacier-ink);
  border-bottom-color: var(--glacier-ink);
}

/* ---------- 五步流程 ---------- */
.page-about .about-flow-wrap {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(22px, 3vw, 38px);
  align-items: start;
  margin-top: clamp(14px, 2vw, 22px);
}

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

.page-about .about-flow__step {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  gap: 12px;
  padding: 16px 0;
  border-top: var(--hairline);
}

.page-about .about-flow__step:last-child {
  border-bottom: var(--hairline);
}

.page-about .about-flow__no {
  font-family: var(--font-mono);
  font-size: var(--fs-sm);
  font-weight: 500;
  letter-spacing: .06em;
  color: var(--glacier-blue);
  padding-top: 4px;
}

.page-about .about-flow__t {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--fs-md);
  line-height: 1.3;
  color: var(--glacier-ink);
  margin: 0 0 6px;
}

.page-about .about-flow__d {
  margin: 0;
  font-size: var(--fs-sm);
  line-height: 1.82;
  color: var(--body-ink);
}

.page-about .about-flow-fig {
  margin: 0;
  border: var(--hairline);
  background-color: var(--glacier-mist);
}

.page-about .about-flow-fig img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
}

/* ---------- 编辑习惯 ---------- */
.page-about .about-std {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(16px, 2.2vw, 24px);
  margin-top: clamp(10px, 1.6vw, 18px);
}

.page-about .about-std__item {
  border-left: 2px solid var(--glacier-mid);
  padding: 2px 0 2px 14px;
}

.page-about .about-std__k {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: .12em;
  color: var(--glacier-blue);
  margin-bottom: 6px;
}

.page-about .about-std__d {
  margin: 0;
  font-size: var(--fs-sm);
  line-height: 1.82;
  color: var(--body-ink);
}

/* ---------- 接下来 ---------- */
.page-about .about-next {
  background-color: var(--glacier-ink);
  padding: clamp(22px, 3.4vw, 40px);
  border: 1px solid var(--glacier-deep);
  margin-top: clamp(10px, 1.6vw, 18px);
}

.page-about .about-next__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(18px, 3vw, 34px);
}

.page-about .about-next__t {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--fs-md);
  line-height: 1.32;
  color: var(--snow-white);
  margin: 0 0 8px;
}

.page-about .about-next__d {
  margin: 0;
  font-size: var(--fs-sm);
  line-height: 1.85;
  color: var(--glacier-mist);
}

/* ---------- 收尾行动条 ---------- */
.page-about .about-cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-top: clamp(22px, 3vw, 34px);
  padding: clamp(18px, 2.6vw, 28px);
  background-color: var(--snow-white);
  border: var(--hairline);
  border-left: 3px solid var(--maple-red);
}

.page-about .about-cta__t {
  margin: 0;
  font-size: var(--fs-body);
  line-height: 1.7;
  color: var(--glacier-ink);
  max-width: 30em;
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

/* ---------- 平板与桌面 ---------- */
@media (min-width: 640px) {
  .page-about .about-aud {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-std {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

@media (min-width: 760px) {
  .page-about .about-rev {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 880px) {
  .page-about .about-flow-wrap {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, .9fr);
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1fr) 116px;
    align-items: start;
  }

  .page-about .about-hero__side {
    display: block;
    align-self: stretch;
    border-left: var(--hairline);
    padding-left: 18px;
    padding-top: 6px;
  }

  .page-about .about-hero__sideText {
    writing-mode: vertical-rl;
    font-family: var(--font-mono);
    font-size: var(--fs-mono);
    letter-spacing: .22em;
    color: var(--glacier-blue);
    margin: 0;
    line-height: 1.6;
  }
}

@media (min-width: 1000px) {
  .page-about .about-shell {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
  }

  .page-about .index-rail {
    flex-direction: column;
    gap: 2px;
    overflow: visible;
    padding: 0 0 0 16px;
    border-bottom: 0;
    border-left: var(--hairline);
    top: 96px;
  }

  .page-about .index-rail__link {
    padding: 8px 10px;
    border-left: 2px solid transparent;
  }

  .page-about .index-rail__link[aria-current="true"] {
    transform: translateX(2px);
  }
}

/* ---------- 窄屏收束 ---------- */
@media (max-width: 700px) {
  .page-about .about-tl-frame {
    aspect-ratio: 3 / 2;
  }

  .page-about .about-hero__wash {
    right: -26%;
    width: 78%;
  }

  .page-about .about-tl__sum {
    grid-template-columns: 56px minmax(0, 1fr) 16px;
  }

  .page-about .about-flow__step {
    grid-template-columns: 34px minmax(0, 1fr);
    gap: 10px;
  }

  .page-about .about-cta__actions .btn {
    flex: 1 1 auto;
  }
}

@media (max-width: 420px) {
  .page-about .about-hero__facts {
    grid-template-columns: minmax(0, 1fr);
  }

  .page-about .about-tl__head {
    font-size: var(--fs-body);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .index-rail__link,
  .page-about .about-tl__item::before,
  .page-about .about-aud__link {
    transition: none;
  }

  .page-about .index-rail__link[aria-current="true"] {
    transform: none;
  }
}