.page-about {
  --about-line: rgba(232, 217, 168, 0.28);
  --about-hair: rgba(28, 35, 32, 0.14);
  --about-rail-w: 210px;
  background: var(--vi-ivory-50);
  color: var(--vi-graphite-900);
  font-family: var(--vi-font-body);
  font-size: 16px;
  line-height: 1.85;
  overflow-x: clip;
}

/* ---------- 顶部深色开篇 ---------- */
.page-about .about-top {
  position: relative;
  background: var(--vi-ink-950);
  color: var(--vi-ivory-50);
  padding-block: clamp(18px, 3vw, 28px) clamp(34px, 6vw, 72px);
  border-bottom: 3px solid var(--vi-gold-500);
  overflow: hidden;
}

.page-about .about-top::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(
    90deg,
    rgba(201, 162, 74, 0.07) 0 1px,
    transparent 1px 76px
  );
  pointer-events: none;
}

.page-about .about-top .vi-shell {
  position: relative;
  z-index: 1;
}

.page-about .about-crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  margin: 0 0 clamp(20px, 3.4vw, 34px);
  font-family: var(--vi-font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
}

.page-about .about-crumbs .vi-crumbs__item {
  color: rgba(247, 242, 231, 0.62);
  text-decoration: none;
}

.page-about .about-crumbs a.vi-crumbs__item:hover,
.page-about .about-crumbs a.vi-crumbs__item:focus-visible {
  color: var(--vi-gold-200);
  text-decoration: underline;
  text-underline-offset: 4px;
}

.page-about .about-crumbs .vi-crumbs__item[aria-current="page"] {
  color: var(--vi-gold-500);
}

.page-about .about-crumbs .vi-crumbs__item + .vi-crumbs__item::before {
  content: "/";
  margin-right: 6px;
  color: rgba(232, 217, 168, 0.4);
}

.page-about .about-hero {
  display: grid;
  gap: clamp(24px, 4vw, 44px);
}

.page-about .about-kicker {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 16px;
  font-family: var(--vi-font-mono);
  font-size: 11.5px;
  letter-spacing: 0.2em;
  color: var(--vi-gold-500);
}

.page-about .about-kicker::before {
  content: "";
  width: 34px;
  height: 1px;
  background: var(--vi-gold-500);
  flex: none;
}

.page-about .about-hero__title {
  margin: 0;
  font-family: var(--vi-font-display);
  font-weight: 800;
  font-size: clamp(31px, 7vw, 58px);
  line-height: 1.18;
  letter-spacing: -0.01em;
  color: var(--vi-ivory-50);
}

.page-about .about-hero__lede {
  max-width: 58ch;
  margin: clamp(16px, 2.6vw, 26px) 0 0;
  font-size: clamp(15px, 2.2vw, 17px);
  line-height: 1.95;
  color: rgba(247, 242, 231, 0.82);
}

.page-about .about-hero__facts {
  display: grid;
  margin: 0;
  border-top: 1px solid var(--about-line);
}

.page-about .about-fact {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 4px 14px;
  align-items: baseline;
  padding: 11px 0;
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-fact dt {
  font-size: 13px;
  letter-spacing: 0.04em;
  color: rgba(247, 242, 231, 0.6);
}

.page-about .about-fact dd {
  margin: 0;
  font-family: var(--vi-font-mono);
  font-size: 13.5px;
  color: var(--vi-gold-500);
  text-align: right;
}

.page-about .about-hero__figure {
  margin: clamp(26px, 5vw, 52px) 0 0;
  border: 1px solid rgba(232, 217, 168, 0.34);
}

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

.page-about .about-hero__figure .vi-figure__cap {
  font-size: 12px;
  letter-spacing: 0.04em;
  color: rgba(247, 242, 231, 0.6);
}

/* ---------- 主体：轨道 + 长卷 ---------- */
.page-about .about-body {
  display: grid;
  gap: clamp(26px, 4vw, 56px);
  padding-block: clamp(34px, 6vw, 78px) clamp(40px, 7vw, 90px);
}

.page-about .about-rail__label {
  display: none;
  margin: 0 0 12px;
  font-family: var(--vi-font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--vi-steel-400);
}

.page-about .about-rail__list {
  display: flex;
  gap: 8px;
  margin: 0;
  padding: 0 0 8px;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-rail__link {
  display: grid;
  grid-template-columns: 26px 1fr;
  gap: 8px;
  align-items: baseline;
  padding: 7px 12px;
  border: 1px solid var(--about-hair);
  background: var(--vi-paper-0);
  color: var(--vi-ink-800);
  text-decoration: none;
  white-space: nowrap;
  font-size: 13.5px;
  transition: border-color 0.2s ease, background-color 0.2s ease, color 0.2s ease;
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  border-color: var(--vi-gold-500);
  background: var(--vi-ivory-100);
}

.page-about .about-rail__num {
  font-family: var(--vi-font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: var(--vi-moss-600);
}

/* ---------- 章节 ---------- */
.page-about .about-sec {
  padding-block: clamp(28px, 4.5vw, 54px);
  border-top: 1px solid var(--about-hair);
  scroll-margin-top: 96px;
}

.page-about .about-sec:first-child {
  padding-top: 0;
  border-top: 0;
}

.page-about .about-head {
  display: grid;
  gap: 12px;
  margin-bottom: clamp(16px, 2.6vw, 26px);
}

.page-about .about-head__num {
  position: relative;
  display: inline-block;
  padding-bottom: 10px;
  font-family: var(--vi-font-mono);
  font-size: clamp(22px, 4vw, 30px);
  font-weight: 600;
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--vi-gold-500);
}

.page-about .about-head__num::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 46px;
  height: 2px;
  background: var(--vi-gold-500);
}

.page-about .about-head__title {
  margin: 0;
  font-family: var(--vi-font-display);
  font-weight: 800;
  font-size: clamp(23px, 4.6vw, 37px);
  line-height: 1.3;
  letter-spacing: -0.005em;
  color: var(--vi-ink-950);
}

.page-about .about-p {
  max-width: 62ch;
  margin: 0 0 1.05em;
  font-size: clamp(15px, 2vw, 16.5px);
  line-height: 1.95;
}

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

/* ---------- 准则卡 ---------- */
.page-about .about-note {
  margin-top: clamp(20px, 3vw, 30px);
  padding: clamp(18px, 2.6vw, 26px);
  background: var(--vi-paper-0);
  border: 2px solid var(--vi-ink-800);
  box-shadow: var(--vi-shadow-hard);
}

.page-about .about-note__title {
  margin: 0 0 14px;
  font-family: var(--vi-font-mono);
  font-size: 11.5px;
  letter-spacing: 0.18em;
  color: var(--vi-moss-600);
}

.page-about .about-note__list {
  display: grid;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-note__list li {
  position: relative;
  padding-left: 20px;
  font-size: 15px;
  line-height: 1.8;
}

.page-about .about-note__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.74em;
  width: 8px;
  height: 8px;
  background: var(--vi-gold-500);
}

/* ---------- 错位变化卡 ---------- */
.page-about .about-steps {
  display: grid;
  gap: clamp(18px, 2.6vw, 26px);
  margin-top: clamp(20px, 3vw, 30px);
}

.page-about .about-step {
  position: relative;
  padding: clamp(18px, 2.6vw, 26px);
  background: var(--vi-paper-0);
  border: 2px solid var(--vi-ink-800);
  box-shadow: var(--vi-shadow-hard);
}

.page-about .about-step__flag {
  position: absolute;
  top: -11px;
  right: 14px;
  padding: 2px 9px;
  background: var(--vi-brick-500);
  color: var(--vi-paper-0);
  font-family: var(--vi-font-mono);
  font-size: 10.5px;
  letter-spacing: 0.12em;
}

.page-about .about-step__idx {
  display: inline-block;
  margin-bottom: 12px;
  padding: 3px 9px;
  background: var(--vi-ink-800);
  color: var(--vi-ivory-50);
  font-family: var(--vi-font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
}

.page-about .about-step__title {
  margin: 0 0 10px;
  font-family: var(--vi-font-display);
  font-weight: 800;
  font-size: clamp(19px, 2.8vw, 23px);
  line-height: 1.4;
  color: var(--vi-ink-950);
}

.page-about .about-step__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
}

/* ---------- 刻度条与编号 ---------- */
.page-about .about-scale-wrap {
  margin: clamp(20px, 3vw, 30px) 0;
  padding: clamp(14px, 2.2vw, 22px);
  background: var(--vi-ivory-100);
  border: 1px solid var(--about-hair);
}

.page-about .about-scale {
  display: block;
  width: 100%;
  height: auto;
}

.page-about .about-codes {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 14px;
}

.page-about .about-codes span {
  padding: 2px 7px;
  background: var(--vi-paper-0);
  border: 1px solid rgba(28, 35, 32, 0.18);
  font-family: var(--vi-font-mono);
  font-size: 11px;
  letter-spacing: 0.04em;
  color: var(--vi-moss-600);
}

/* ---------- 图片 ---------- */
.page-about .about-fig-tall {
  margin: clamp(22px, 3.4vw, 34px) 0;
  border: 1px solid var(--about-hair);
}

.page-about .about-fig-wide {
  margin: clamp(24px, 3.6vw, 36px) 0 0;
  border: 1px solid var(--about-hair);
}

.page-about .about-fig-tall img,
.page-about .about-fig-wide img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .about-fig-tall .vi-figure__cap,
.page-about .about-fig-wide .vi-figure__cap {
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--vi-steel-400);
}

/* ---------- 按钮组 ---------- */
.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(18px, 2.8vw, 28px);
}

/* ---------- A-F 折叠卡 ---------- */
.page-about .about-codes-grid {
  display: grid;
  gap: 10px;
  margin-top: clamp(18px, 3vw, 26px);
}

.page-about .about-code {
  background: var(--vi-paper-0);
  border: 1px solid var(--about-hair);
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.page-about .about-code[open] {
  border-color: var(--vi-gold-500);
  background: var(--vi-ivory-50);
}

.page-about .about-code__sum {
  display: grid;
  grid-template-columns: 34px 1fr 14px;
  gap: 10px;
  align-items: center;
  padding: 12px 14px;
  list-style: none;
  cursor: pointer;
  font-size: 15px;
}

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

.page-about .about-code__sum:focus-visible {
  outline: 2px solid var(--vi-cyan-500);
  outline-offset: 2px;
}

.page-about .about-code__k {
  border: 1px solid rgba(201, 162, 74, 0.55);
  text-align: center;
  font-family: var(--vi-font-mono);
  font-size: 14px;
  font-weight: 600;
  line-height: 1.7;
  color: var(--vi-gold-500);
}

.page-about .about-code__t {
  font-family: var(--vi-font-display);
  font-weight: 700;
  font-size: 16.5px;
  color: var(--vi-ink-950);
}

.page-about .about-code__sign {
  position: relative;
  width: 12px;
  height: 12px;
}

.page-about .about-code__sign::before,
.page-about .about-code__sign::after {
  content: "";
  position: absolute;
  background: var(--vi-moss-600);
  transition: transform 0.2s ease;
}

.page-about .about-code__sign::before {
  left: 0;
  top: 5px;
  width: 12px;
  height: 2px;
}

.page-about .about-code__sign::after {
  left: 5px;
  top: 0;
  width: 2px;
  height: 12px;
}

.page-about .about-code[open] .about-code__sign::after {
  transform: scaleY(0);
}

.page-about .about-code__body {
  margin: 0;
  padding: 0 16px 16px 58px;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--vi-graphite-900);
}

/* ---------- 后续方向 ---------- */
.page-about .about-next {
  margin-top: clamp(18px, 3vw, 26px);
  border-top: 1px solid var(--about-hair);
}

.page-about .about-next__item {
  display: grid;
  gap: 6px;
  padding: clamp(16px, 2.4vw, 22px) 0;
  border-bottom: 1px solid var(--about-hair);
}

.page-about .about-next__key {
  margin: 0;
  font-family: var(--vi-font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--vi-moss-600);
}

.page-about .about-next__text {
  margin: 0;
  max-width: 60ch;
  font-size: 15px;
  line-height: 1.9;
}

/* ---------- 结尾入口块 ---------- */
.page-about .about-cta {
  margin-top: clamp(32px, 5.5vw, 66px);
  padding: clamp(24px, 4.4vw, 46px);
  background: var(--vi-ink-800);
  color: var(--vi-ivory-50);
  border-left: 6px solid var(--vi-gold-500);
}

.page-about .about-cta__title {
  margin: 0 0 12px;
  font-family: var(--vi-font-display);
  font-weight: 800;
  font-size: clamp(21px, 3.8vw, 30px);
  line-height: 1.38;
  color: var(--vi-ivory-50);
}

.page-about .about-cta__text {
  margin: 0;
  max-width: 60ch;
  font-size: 15px;
  line-height: 1.9;
  color: rgba(247, 242, 231, 0.82);
}

.page-about .about-cta .vi-btn {
  border-color: rgba(232, 217, 168, 0.55);
  color: var(--vi-ivory-50);
}

.page-about .about-cta .vi-btn:hover,
.page-about .about-cta .vi-btn:focus-visible {
  border-color: var(--vi-gold-500);
  color: var(--vi-gold-200);
}

.page-about .about-cta .vi-btn--gold {
  color: var(--vi-ink-950);
}

.page-about .about-cta .vi-btn--gold:hover,
.page-about .about-cta .vi-btn--gold:focus-visible {
  color: var(--vi-ink-950);
}

/* ---------- 桌面布局 ---------- */
@media (min-width: 900px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 1.62fr) minmax(0, 0.88fr);
    align-items: end;
    gap: clamp(32px, 5vw, 72px);
  }

  .page-about .about-hero__facts {
    padding-bottom: 4px;
  }

  .page-about .about-body {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    align-items: start;
    gap: clamp(34px, 4.5vw, 64px);
  }

  .page-about .about-rail {
    position: sticky;
    top: 92px;
  }

  .page-about .about-rail__label {
    display: block;
  }

  .page-about .about-rail__list {
    display: grid;
    gap: 6px;
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .about-rail__link {
    white-space: normal;
    padding: 10px 12px;
  }

  .page-about .about-fig-tall {
    max-width: 420px;
  }
}

@media (min-width: 820px) {
  .page-about .about-steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    align-items: start;
  }

  .page-about .about-step:nth-child(2) {
    margin-top: 42px;
  }

  .page-about .about-step:nth-child(3) {
    margin-top: -18px;
  }

  .page-about .about-next__item {
    grid-template-columns: 148px minmax(0, 1fr);
    gap: 6px 22px;
    align-items: start;
  }

  .page-about .about-next__key {
    padding-top: 4px;
  }
}

@media (min-width: 760px) {
  .page-about .about-codes-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
  }
}

@media (min-width: 1024px) {
  .page-about .about-head {
    grid-template-columns: 1fr;
    gap: 10px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition: none !important;
    animation: none !important;
  }
}