.page-about {
  --about-rail: 150px;
  --about-note: 200px;
  --about-rule: rgba(107, 31, 46, .26);
  --about-gap: 3rem;
  background: var(--cream);
  color: var(--ink);
  font-family: var(--font-text);
  overflow-x: clip;
}

.page-about .about-top {
  padding-top: calc(var(--header-h) + 2.5rem);
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumb {
  display: flex;
  align-items: center;
  gap: .5rem;
  font-size: .8125rem;
  color: var(--ink-50);
  margin-bottom: 2.25rem;
}

.page-about .about-crumb a {
  color: var(--ink-70);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease-out), border-color var(--dur) var(--ease-out);
}

.page-about .about-crumb a:hover {
  color: var(--wine);
  border-bottom-color: var(--gilt);
}

.page-about .about-crumb__sep {
  color: var(--mist);
}

/* ---------- 页面题头 ---------- */
.page-about .about-head {
  max-width: 46rem;
  padding-bottom: 2.75rem;
  border-bottom: 1px solid var(--about-rule);
}

.page-about .about-head h1 {
  font-family: var(--font-display);
  font-size: clamp(2.1rem, 5.2vw, 3.6rem);
  line-height: 1.1;
  font-weight: 700;
  letter-spacing: -.01em;
  margin: .9rem 0 1.4rem;
  color: var(--ink);
}

.page-about .about-head .lede {
  font-size: clamp(1rem, 1.6vw, 1.125rem);
  line-height: 1.8;
  color: var(--ink-82);
  max-width: 34em;
  margin: 0 0 1.15rem;
}

.page-about .about-head__note {
  max-width: 34em;
  margin: 0;
  font-size: .875rem;
  line-height: 1.75;
  color: var(--ink-50);
  padding-left: .9rem;
  border-left: 2px solid var(--gilt-line);
}

/* ---------- 档案图 ---------- */
.page-about .about-plate {
  margin: 2.75rem auto 0;
}

.page-about .about-plate__frame {
  position: relative;
  border-radius: var(--radius-m);
  overflow: hidden;
  border: 1px solid var(--gilt-line);
  background: linear-gradient(140deg, var(--ember), var(--cellar));
  aspect-ratio: 1400 / 900;
}

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

.page-about .about-plate__cap {
  margin-top: .9rem;
  font-size: .8125rem;
  line-height: 1.65;
  color: var(--mist);
  max-width: 46em;
}

/* ---------- 主体三栏 ---------- */
.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 2.5rem;
  padding-top: 3.5rem;
  padding-bottom: 5.5rem;
}

/* ---------- 左侧档案脊背 ---------- */
.page-about .about-rail__title {
  margin: 0 0 .9rem;
  font-family: var(--font-num);
  font-size: .6875rem;
  letter-spacing: .22em;
  color: var(--mist);
}

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

.page-about .about-rail__list::before {
  content: "";
  position: absolute;
  left: 5px;
  top: .7rem;
  bottom: .7rem;
  width: 1px;
  background: linear-gradient(180deg, var(--gilt-line), var(--about-rule));
}

.page-about .about-rail__link {
  position: relative;
  display: block;
  padding: .5rem 0 .5rem 1.4rem;
  font-size: .875rem;
  line-height: 1.4;
  color: var(--ink-70);
  text-decoration: none;
  transition: color var(--dur) var(--ease-out);
}

.page-about .about-rail__link::before {
  content: "";
  position: absolute;
  left: 1px;
  top: 50%;
  width: 9px;
  height: 9px;
  margin-top: -5px;
  border-radius: 50%;
  background: var(--cream);
  border: 1px solid var(--mist);
  transition: background var(--dur) var(--ease-out), border-color var(--dur) var(--ease-out), box-shadow var(--dur) var(--ease-out);
}

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

.page-about .about-rail__link:hover::before {
  border-color: var(--wine);
  background: var(--gilt-wash);
}

.page-about .about-rail__link[aria-current] {
  color: var(--wine);
  font-weight: 600;
}

.page-about .about-rail__link[aria-current]::before {
  background: var(--wine);
  border-color: var(--wine);
  box-shadow: 0 0 0 3px var(--gilt-wash);
}

.page-about .about-rail__link:focus-visible {
  outline: 2px solid var(--gilt);
  outline-offset: 2px;
  border-radius: var(--radius-s);
}

/* ---------- 章节 ---------- */
.page-about .about-chapter {
  padding-top: 2.25rem;
  border-top: 1px solid var(--about-rule);
  scroll-margin-top: calc(var(--header-h) + 2.5rem);
}

.page-about .about-chapter + .about-chapter {
  margin-top: 3.5rem;
}

.page-about .about-chapter__head {
  display: flex;
  align-items: center;
  gap: .9rem;
  margin-bottom: 1.2rem;
}

.page-about .about-chapter__no {
  flex: none;
  display: inline-grid;
  place-items: center;
  min-width: 2.3rem;
  height: 2.1rem;
  padding: 0 .45rem;
  font-family: var(--font-num);
  font-size: .8125rem;
  letter-spacing: .08em;
  color: var(--gilt);
  background: var(--cellar);
  border-radius: var(--radius-s);
}

.page-about .about-chapter h2 {
  font-family: var(--font-display);
  font-size: clamp(1.35rem, 2.6vw, 1.8rem);
  line-height: 1.3;
  font-weight: 600;
  margin: 0;
  color: var(--ink);
}

.page-about .about-chapter p {
  max-width: 36em;
  margin: 0 0 1.05rem;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--ink-82);
}

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

.page-about .about-chapter a {
  color: var(--wine);
  text-decoration: none;
  border-bottom: 1px solid var(--gilt-line);
  transition: border-color var(--dur) var(--ease-out), color var(--dur) var(--ease-out);
}

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

.page-about .about-chapter a:focus-visible {
  outline: 2px solid var(--gilt);
  outline-offset: 2px;
}

/* ---------- 术语小注 ---------- */
.page-about .about-term {
  position: relative;
  display: inline-block;
  color: var(--ink);
  border-bottom: 1px dashed var(--gilt);
  cursor: help;
}

.page-about .about-term:focus-visible {
  outline: 2px solid var(--gilt);
  outline-offset: 3px;
  border-radius: 2px;
}

.page-about .about-term__tip {
  position: absolute;
  left: 0;
  bottom: calc(100% + .55rem);
  width: min(18rem, 72vw);
  padding: .65rem .8rem;
  background: var(--ink);
  color: var(--snow);
  font-size: .8125rem;
  line-height: 1.65;
  font-weight: 400;
  letter-spacing: 0;
  border: 1px solid var(--gilt-line);
  border-radius: var(--radius-s);
  opacity: 0;
  visibility: hidden;
  transform: translateY(4px);
  transition: opacity var(--dur) var(--ease-out), transform var(--dur) var(--ease-out), visibility var(--dur);
  z-index: 6;
  pointer-events: none;
}

.page-about .about-term:hover .about-term__tip,
.page-about .about-term:focus .about-term__tip,
.page-about .about-term:focus-visible .about-term__tip {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

/* ---------- 档位编号表 ---------- */
.page-about .about-serial {
  margin: 1.75rem 0 1.5rem;
  max-width: 36em;
}

.page-about .about-serial__group + .about-serial__group {
  margin-top: 1.75rem;
}

.page-about .about-serial__group-title {
  display: flex;
  align-items: baseline;
  gap: .3rem;
  margin: 0 0 .5rem;
  padding-bottom: .45rem;
  border-bottom: 1px solid var(--gilt-line);
  font-size: .8125rem;
  font-weight: 600;
  letter-spacing: .06em;
  color: var(--wine);
}

.page-about .about-serial__group-title .num {
  font-family: var(--font-num);
  letter-spacing: .04em;
}

.page-about .about-serial__item {
  border-bottom: 1px solid var(--hairline-soft);
}

.page-about .about-serial__item summary {
  display: flex;
  align-items: center;
  gap: .85rem;
  padding: .68rem .35rem;
  list-style: none;
  cursor: pointer;
  border-radius: var(--radius-s);
  transition: background var(--dur) var(--ease-out), transform var(--dur) var(--ease-out);
}

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

.page-about .about-serial__item summary::after {
  content: "＋";
  flex: none;
  font-size: .875rem;
  line-height: 1;
  color: var(--mist);
  transition: color var(--dur) var(--ease-out), transform var(--dur) var(--ease-out);
}

.page-about .about-serial__item[open] summary::after {
  content: "－";
  color: var(--wine);
}

.page-about .about-serial__item summary:hover {
  background: var(--gilt-wash);
  transform: translateX(2px);
}

.page-about .about-serial__item summary:focus-visible {
  outline: 2px solid var(--gilt);
  outline-offset: 2px;
}

.page-about .about-serial__item[open] summary {
  background: var(--archive-wash);
}

.page-about .about-serial__no {
  flex: none;
  display: inline-grid;
  place-items: center;
  min-width: 2.1rem;
  padding: .15rem .35rem;
  font-family: var(--font-num);
  font-size: .8125rem;
  letter-spacing: .08em;
  color: var(--gilt);
  background: var(--cellar);
  border-radius: var(--radius-s);
}

.page-about .about-serial__name {
  flex: 1;
  font-size: .9375rem;
  color: var(--ink);
}

.page-about .about-serial__item p {
  margin: 0;
  padding: .1rem 0 .9rem 3.3rem;
  max-width: none;
  font-size: .875rem;
  line-height: 1.75;
  color: var(--ink-70);
}

/* ---------- 章节内插图 ---------- */
.page-about .about-inline {
  margin: 2rem 0 1.75rem;
  max-width: 36em;
}

.page-about .about-inline__frame {
  border-radius: var(--radius-m);
  overflow: hidden;
  border: 1px solid var(--gilt-line);
  background: linear-gradient(150deg, var(--wine), var(--cellar));
}

.page-about .about-inline--square .about-inline__frame {
  aspect-ratio: 1 / 1;
}

.page-about .about-inline--wide .about-inline__frame {
  aspect-ratio: 3 / 2;
}

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

.page-about .about-inline figcaption {
  margin-top: .75rem;
  font-size: .8125rem;
  line-height: 1.65;
  color: var(--mist);
}

/* ---------- 右侧小注栏 ---------- */
.page-about .about-notes__title {
  margin: 0 0 .9rem;
  font-family: var(--font-num);
  font-size: .6875rem;
  letter-spacing: .22em;
  color: var(--mist);
}

.page-about .about-notes__list {
  margin: 0;
  display: grid;
  gap: .9rem;
}

.page-about .about-notes__item {
  padding-left: .8rem;
  border-left: 2px solid var(--gilt-line);
}

.page-about .about-notes__item dt {
  font-size: .8125rem;
  font-weight: 600;
  color: var(--wine);
  letter-spacing: .04em;
}

.page-about .about-notes__item dd {
  margin: .25rem 0 0;
  font-size: .8125rem;
  line-height: 1.7;
  color: var(--ink-70);
}

/* ---------- 核对入口 ---------- */
.page-about .about-links {
  display: grid;
  gap: .85rem;
  margin: 1.6rem 0 1.5rem;
  max-width: 36em;
}

.page-about .about-links__item {
  display: block;
  padding: 1.05rem 1.2rem;
  border: 1px solid var(--about-rule);
  border-left: 3px solid var(--wine);
  border-radius: var(--radius-s);
  background: var(--snow);
  text-decoration: none;
  transition: transform var(--dur) var(--ease-out), border-color var(--dur) var(--ease-out), background var(--dur) var(--ease-out);
}

.page-about .about-links__item:hover {
  transform: translateY(-2px);
  border-left-color: var(--gilt);
  background: var(--gilt-wash);
}

.page-about .about-links__item:focus-visible {
  outline: 2px solid var(--gilt);
  outline-offset: 3px;
}

.page-about .about-links__label {
  display: block;
  font-family: var(--font-display);
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--ink);
  margin-bottom: .3rem;
}

.page-about .about-links__desc {
  display: block;
  font-size: .875rem;
  line-height: 1.7;
  color: var(--ink-70);
}

/* ---------- 中屏：两栏 ---------- */
@media (min-width: 900px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    column-gap: var(--about-gap);
  }

  .page-about .about-notes {
    grid-column: 2;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
    gap: 1.1rem 1.5rem;
    align-items: start;
    padding-top: 2.25rem;
    border-top: 1px solid var(--about-rule);
  }

  .page-about .about-notes__title {
    grid-column: 1 / -1;
    margin-bottom: 0;
  }

  .page-about .about-notes__list {
    grid-column: 1 / -1;
    grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
    gap: 1.1rem 1.5rem;
  }
}

/* ---------- 宽屏：三栏 + 粘性 ---------- */
@media (min-width: 1040px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail) minmax(0, 36em) var(--about-note);
  }

  .page-about .about-rail,
  .page-about .about-notes {
    position: sticky;
    top: calc(var(--header-h) + 2rem);
    align-self: start;
  }

  .page-about .about-notes {
    grid-column: 3;
    display: block;
    padding-top: 0;
    border-top: 0;
  }

  .page-about .about-notes__title {
    grid-column: auto;
    margin-bottom: .9rem;
  }

  .page-about .about-notes__list {
    grid-column: auto;
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    gap: .9rem;
  }
}

/* ---------- 窄屏：索引转横向 ---------- */
@media (max-width: 899.98px) {
  .page-about .about-top {
    padding-top: calc(var(--header-h) + 1.75rem);
  }

  .page-about .about-crumb {
    margin-bottom: 1.5rem;
  }

  .page-about .about-head {
    padding-bottom: 2rem;
  }

  .page-about .about-plate {
    margin-top: 2rem;
  }

  .page-about .about-body {
    padding-top: 2.25rem;
    padding-bottom: 3.5rem;
    gap: 2rem;
  }

  .page-about .about-rail {
    border-bottom: 1px solid var(--about-rule);
    padding-bottom: .5rem;
  }

  .page-about .about-rail__list {
    display: flex;
    gap: .2rem;
    overflow-x: auto;
    padding-bottom: .3rem;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: thin;
  }

  .page-about .about-rail__list::before {
    display: none;
  }

  .page-about .about-rail__link {
    white-space: nowrap;
    padding: .5rem .85rem;
    border-left: 2px solid transparent;
    font-size: .8125rem;
  }

  .page-about .about-rail__link::before {
    display: none;
  }

  .page-about .about-rail__link[aria-current] {
    border-left-color: var(--wine);
    background: var(--gilt-wash);
  }
}

@media (max-width: 520px) {
  .page-about .about-serial__item p {
    padding-left: .35rem;
  }

  .page-about .about-serial__item summary {
    gap: .6rem;
    padding: .65rem .2rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-links__item:hover,
  .page-about .about-serial__item summary:hover {
    transform: none;
  }

  .page-about .about-term__tip {
    transition: opacity var(--dur) linear;
    transform: none;
  }
}
<<<END>>>