.page-about {
  --about-rule: rgba(110, 106, 98, 0.3);
  --about-gold-soft: rgba(199, 163, 74, 0.12);
  background: var(--rice);
  color: var(--ink);
  overflow-x: hidden;
}

.page-about *,
.page-about *::before,
.page-about *::after {
  box-sizing: border-box;
}

/* ---------- 首屏拼贴 ---------- */

.page-about .about-hero {
  position: relative;
  padding: 22px 0 52px;
  background-color: var(--green);
  background-image:
    repeating-linear-gradient(0deg, transparent 0 43px, rgba(183, 176, 163, 0.08) 43px 44px),
    repeating-linear-gradient(90deg, transparent 0 43px, rgba(183, 176, 163, 0.08) 43px 44px);
  color: var(--rice);
  border-bottom: 2px solid var(--gold);
}

.page-about .about-hero__crumb {
  font-size: 13px;
  color: var(--gold-light);
}

.page-about .about-hero__crumb a {
  color: var(--gold-light);
  text-decoration: none;
  border-bottom: 1px solid var(--gold-line);
}

.page-about .about-hero__crumb a:hover {
  color: var(--rice);
}

.page-about .about-hero__grid {
  display: grid;
  gap: 30px;
  margin-top: 26px;
}

.page-about .about-hero__eyebrow {
  color: var(--gold);
  letter-spacing: 0.16em;
}

.page-about .about-hero h1 {
  margin: 10px 0 0;
  font-family: var(--serif);
  font-weight: 800;
  font-size: clamp(30px, 6.2vw, 54px);
  line-height: 1.24;
  letter-spacing: 0.02em;
  color: var(--rice);
}

.page-about .about-hero__intro {
  margin: 20px 0 0;
  font-size: 17px;
  line-height: 1.9;
  color: rgba(247, 242, 231, 0.86);
  max-width: 60ch;
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

.page-about .about-hero .btn--ghost {
  background: transparent;
  color: var(--rice);
  border-color: rgba(247, 242, 231, 0.5);
}

.page-about .about-hero .btn--ghost:hover {
  background: var(--rice);
  color: var(--green-deep);
  border-color: var(--rice);
}

.page-about .about-hero__figure {
  margin: 0;
  border: 2px solid var(--gold-line);
  box-shadow: var(--hard-shadow);
}

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

.page-about .about-hero__stats {
  list-style: none;
  margin: 44px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--gold-line);
  border: 2px solid var(--gold-line);
}

.page-about .about-hero__stats li {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 16px 16px 18px;
  background: var(--green-deep);
}

.page-about .about-hero__stats .num {
  font-family: var(--mono);
  font-size: 28px;
  line-height: 1.1;
  color: var(--gold-light);
  letter-spacing: 0.02em;
}

.page-about .about-hero__stat-label {
  font-size: 13px;
  line-height: 1.5;
  color: rgba(247, 242, 231, 0.7);
}

/* ---------- 主体与章节索引 ---------- */

.page-about .about-main {
  padding: 52px 0 68px;
}

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

.page-about .about-toc {
  align-self: start;
  padding-left: 14px;
  border-left: 2px solid var(--gold);
}

.page-about .about-toc .toc__title {
  margin: 0;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--stone);
}

.page-about .about-toc .toc__list {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .about-toc .toc__link {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  padding: 8px 8px 8px 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--stone);
  text-decoration: none;
  transition: color 0.18s ease, background-color 0.18s ease;
}

.page-about .about-toc .toc__link::before {
  content: "";
  flex: none;
  width: 9px;
  height: 9px;
  margin-top: 5px;
  border: 1.5px solid var(--gold);
  border-radius: 50%;
  transition: background-color 0.18s ease, transform 0.18s ease;
}

.page-about .about-toc .toc__link:hover {
  color: var(--green-deep);
}

.page-about .about-toc .toc__link[aria-current="true"] {
  color: var(--green-deep);
  background: var(--gold-light);
  padding-left: 8px;
  font-weight: 600;
}

.page-about .about-toc .toc__link[aria-current="true"]::before {
  background: var(--gold);
  transform: scale(1.05);
}

.page-about .about-toc__hint {
  margin: 16px 0 0;
  font-size: 12px;
  line-height: 1.6;
  color: var(--stone);
}

/* ---------- 章节排版 ---------- */

.page-about .about-chapters {
  display: grid;
  gap: 6px;
}

.page-about .chapter {
  padding: 26px 0 34px;
  border-bottom: 1px solid var(--about-rule);
}

.page-about .chapter:last-child {
  border-bottom: 0;
}

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

.page-about .chapter__head .eyebrow {
  color: var(--clay);
  letter-spacing: 0.18em;
}

.page-about .chapter h2 {
  margin: 8px 0 0;
  font-family: var(--serif);
  font-weight: 800;
  font-size: clamp(24px, 4.4vw, 34px);
  line-height: 1.3;
  letter-spacing: 0.02em;
  color: var(--green-deep);
}

.page-about .chapter__body > p {
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.85;
  max-width: 68ch;
}

.page-about .chapter__lead {
  font-size: 18px !important;
  line-height: 1.8 !important;
  color: var(--green-deep);
}

.page-about .chapter__note {
  margin-top: 26px !important;
  padding: 16px 18px;
  background: var(--about-gold-soft);
  border-left: 3px solid var(--gold);
  font-size: 15px !important;
}

.page-about .chess-quote {
  margin: 24px 0 0;
  padding: 18px 20px;
  border-left: 6px solid var(--green);
  background: var(--about-gold-soft);
  font-family: var(--serif);
  font-size: 17px;
  line-height: 1.8;
  color: var(--green-deep);
}

.page-about .chess-quote p {
  margin: 0;
}

.page-about .about-media {
  margin: 26px 0 0;
  max-width: 640px;
}

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

.page-about .about-media figcaption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--stone);
}

/* ---------- 四条主线 ---------- */

.page-about .line-list {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: 2px solid var(--green);
}

.page-about .line-item {
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
  padding: 20px 0;
  border-bottom: 1px solid var(--about-rule);
}

.page-about .line-item__no {
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: 0.14em;
  color: var(--gold);
}

.page-about .line-item h3 {
  margin: 0;
  font-family: var(--serif);
  font-size: 20px;
  font-weight: 700;
  color: var(--green-deep);
}

.page-about .line-item p:last-child {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink);
}

/* ---------- 四步棋 ---------- */

.page-about .move-list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  border-top: 2px solid var(--green);
}

.page-about .move {
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
  padding: 18px 0;
  border-bottom: 1px solid var(--about-rule);
}

.page-about .move__stage {
  margin: 0;
  font-family: var(--serif);
  font-size: 18px;
  font-weight: 700;
  color: var(--clay);
  letter-spacing: 0.08em;
}

.page-about .move h3 {
  margin: 0;
  font-family: var(--sans);
  font-size: 16px;
  font-weight: 600;
  color: var(--green-deep);
}

.page-about .move p:last-child {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink);
}

/* ---------- 会员分级 ---------- */

.page-about .ranks {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
  margin-top: 24px;
}

.page-about .rank {
  padding: 20px 18px 22px;
  background: var(--rice);
  border: 2px solid var(--green);
  box-shadow: var(--hard-shadow);
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.page-about .rank:hover {
  border-color: var(--gold);
  transform: translateY(-3px);
}

.page-about .rank__tier {
  margin: 0;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--lapis);
}

.page-about .rank h3 {
  margin: 8px 0 12px;
  font-family: var(--serif);
  font-size: 20px;
  font-weight: 700;
  color: var(--green-deep);
}

.page-about .rank__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 8px;
}

.page-about .rank__list li {
  position: relative;
  padding-left: 18px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--ink);
}

.page-about .rank__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 8px;
  width: 7px;
  height: 7px;
  background: var(--gold);
}

/* ---------- 里程碑 ---------- */

.page-about .timeline {
  list-style: none;
  margin: 22px 0 0;
  padding: 0 0 0 26px;
  position: relative;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 10px;
  bottom: 14px;
  width: 1px;
  background: var(--gold-line);
}

.page-about .milestone {
  position: relative;
  padding-bottom: 26px;
}

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

.page-about .milestone::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 6px;
  width: 11px;
  height: 11px;
  border: 2px solid var(--gold);
  border-radius: 50%;
  background: var(--rice);
  transition: background-color 0.2s ease;
}

.page-about .milestone:hover::before {
  background: var(--gold);
}

.page-about .milestone__phase {
  margin: 0;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--coral);
}

.page-about .milestone h3 {
  margin: 6px 0 0;
  font-family: var(--serif);
  font-size: 19px;
  font-weight: 700;
  color: var(--green-deep);
}

.page-about .milestone__note {
  margin: 8px 0 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--stone);
  max-width: 62ch;
}

/* ---------- 页尾 ---------- */

.page-about .about-close {
  padding: 48px 0 56px;
  background: var(--green-deep);
  border-top: 2px solid var(--gold);
  color: var(--rice);
}

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

.page-about .about-close__eyebrow {
  color: var(--gold);
  letter-spacing: 0.18em;
}

.page-about .about-close h2 {
  margin: 8px 0 0;
  font-family: var(--serif);
  font-weight: 800;
  font-size: clamp(23px, 4.6vw, 32px);
  line-height: 1.3;
  color: var(--rice);
}

.page-about .about-close__text > p {
  margin: 16px 0 0;
  font-size: 16px;
  line-height: 1.85;
  color: rgba(247, 242, 231, 0.82);
  max-width: 56ch;
}

.page-about .about-close__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.page-about .about-close .btn--ghost {
  background: transparent;
  color: var(--rice);
  border-color: rgba(247, 242, 231, 0.5);
}

.page-about .about-close .btn--ghost:hover {
  background: var(--rice);
  color: var(--green-deep);
  border-color: var(--rice);
}

.page-about .about-close__figure {
  margin: 0;
  max-width: 420px;
  border: 2px solid var(--gold-line);
}

/* ---------- 响应式 ---------- */

@media (min-width: 700px) {
  .page-about .about-hero__stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .page-about .rank:nth-child(2) {
    margin-top: 26px;
  }

  .page-about .rank:nth-child(3) {
    margin-top: 52px;
  }

  .page-about .line-item {
    grid-template-columns: 76px minmax(0, 1fr);
    gap: 4px 18px;
  }

  .page-about .line-item__no {
    grid-row: 1 / span 2;
    padding-top: 4px;
  }

  .page-about .move {
    grid-template-columns: 96px 132px minmax(0, 1fr);
    gap: 18px;
    align-items: baseline;
  }

  .page-about .move__stage,
  .page-about .move h3,
  .page-about .move p:last-child {
    margin: 0;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    padding: 26px 0 62px;
  }

  .page-about .about-hero__grid {
    grid-template-columns: repeat(12, minmax(0, 1fr));
    gap: 36px;
    align-items: start;
  }

  .page-about .about-hero__lede {
    grid-column: 1 / span 7;
  }

  .page-about .about-hero__figure {
    grid-column: 9 / span 4;
    margin-top: 46px;
  }

  .page-about .about-close__grid {
    grid-template-columns: minmax(0, 1fr) 380px;
    gap: 48px;
    align-items: center;
  }

  .page-about .about-close__figure {
    max-width: none;
    justify-self: end;
  }
}

@media (min-width: 1000px) {
  .page-about .index-layout {
    grid-template-columns: 200px minmax(0, 1fr);
    gap: 62px;
  }

  .page-about .about-toc {
    position: sticky;
    top: 96px;
  }

  .page-about .about-media {
    margin-left: 96px;
  }
}

@media (min-width: 1180px) {
  .page-about .index-layout {
    grid-template-columns: 220px minmax(0, 1fr);
    gap: 76px;
  }
}

@media (hover: hover) and (min-width: 760px) {
  .page-about .milestone__note {
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height 0.3s ease, opacity 0.3s ease;
  }

  .page-about .milestone:hover .milestone__note,
  .page-about .milestone:focus-within .milestone__note {
    max-height: 9em;
    opacity: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .rank,
  .page-about .about-toc .toc__link,
  .page-about .about-toc .toc__link::before,
  .page-about .milestone::before,
  .page-about .milestone__note {
    transition: none;
  }
}