.page-about {
  --about-index-w: 246px;
  --about-rule: rgba(18, 58, 50, 0.22);
  background: var(--paper);
  color: var(--ink);
  padding-bottom: 72px;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding: 20px 0 40px;
  background:
    repeating-linear-gradient(180deg, rgba(14, 21, 18, 0.05) 0 1px, transparent 1px 4px),
    var(--paper);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  top: -140px;
  right: -46%;
  width: 118%;
  height: 420px;
  background: linear-gradient(148deg, var(--green) 0%, var(--green-deep) 100%);
  transform: rotate(-8deg);
  opacity: 0.9;
  pointer-events: none;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--red) 40%, var(--gold) 70%, transparent);
  transform: skewY(-0.6deg);
}

.page-about .about-hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 28px;
}

.page-about .about-hero-copy {
  max-width: 62ch;
}

.page-about .about-hero h1 {
  margin: 14px 0 0;
  font-family: var(--font-head);
  font-size: clamp(30px, 7.4vw, 52px);
  line-height: 1.16;
  font-weight: 900;
  letter-spacing: -0.5px;
  color: var(--ink);
  text-shadow: 2px 0 0 rgba(179, 39, 45, 0.28);
}

.page-about .about-hero .lede {
  margin: 18px 0 0;
  font-size: 16px;
  line-height: 1.9;
  color: var(--slate);
}

.page-about .about-hero-points {
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--about-rule);
}

.page-about .about-hero-point {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
  padding: 11px 0;
  border-bottom: 1px solid var(--about-rule);
  font-size: 14px;
}

.page-about .about-point-key {
  flex: 0 0 auto;
  min-width: 76px;
  font-family: var(--font-head);
  font-weight: 800;
  color: var(--red);
  letter-spacing: 0.04em;
}

.page-about .about-point-val {
  flex: 1 1 200px;
  color: var(--ink);
  line-height: 1.7;
}

/* 首屏右侧冻结刻度面板 */
.page-about .about-hero-panel {
  position: relative;
  align-self: start;
  padding: 20px 20px 22px;
  background: var(--card);
  border: 1px solid var(--ink);
  clip-path: polygon(var(--cut) 0, 100% 0, 100% calc(100% - var(--cut)), calc(100% - var(--cut)) 100%, 0 100%, 0 var(--cut));
  box-shadow: var(--shadow-card);
}

.page-about .about-hero-panel::before {
  content: "";
  position: absolute;
  inset: 5px 5px auto auto;
  width: 40px;
  height: 40px;
  border-top: 3px solid var(--gold);
  border-right: 3px solid var(--gold);
  pointer-events: none;
}

.page-about .about-panel-cap {
  margin: 0 0 14px;
  font-family: var(--font-head);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.14em;
  color: var(--green);
}

.page-about .about-year-scale {
  display: flex;
  flex-direction: column;
  gap: 0;
  margin: 0;
  padding: 0;
  list-style: none;
  border-left: 2px solid var(--about-rule);
}

.page-about .about-year-scale .year-scale-item {
  position: relative;
  padding: 7px 0 7px 16px;
  font-family: var(--font-num);
  font-size: 17px;
  letter-spacing: 0.06em;
  color: var(--slate);
}

.page-about .about-year-scale .year-scale-item::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 50%;
  width: 8px;
  height: 2px;
  background: var(--about-rule);
}

.page-about .about-year-scale .year-scale-item.is-current {
  color: var(--red);
  font-weight: 700;
}

.page-about .about-year-scale .year-scale-item.is-current::before {
  height: 10px;
  width: 3px;
  left: -3px;
  top: calc(50% - 5px);
  background: var(--red);
}

.page-about .about-panel-note {
  margin: 16px 0 0;
  padding-top: 14px;
  border-top: 1px dashed var(--about-rule);
  font-size: 13px;
  line-height: 1.8;
  color: var(--slate);
}

/* ---------- 主体布局 ---------- */
.page-about .about-layout {
  display: block;
  padding-top: 34px;
}

/* 移动端索引：横向滚动条 */
.page-about .about-index {
  margin-bottom: 30px;
  padding: 14px 14px 12px;
  background: var(--card);
  border: 1px solid var(--ink);
  border-left: 5px solid var(--green);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);
}

.page-about .about-index-title {
  margin: 0 0 10px;
  font-family: var(--font-head);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.2em;
  color: var(--green);
}

.page-about .about-index-list {
  display: flex;
  gap: 8px;
  margin: 0;
  padding: 0 0 6px;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-index-item {
  flex: 0 0 auto;
}

.page-about .about-index-link {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border: 1px solid var(--about-rule);
  border-radius: 2px;
  background: var(--paper);
  color: var(--ink);
  font-size: 13px;
  line-height: 1.4;
  text-decoration: none;
  white-space: nowrap;
  transition: transform 0.2s var(--ease), border-color 0.2s var(--ease);
}

.page-about .about-index-num {
  font-family: var(--font-num);
  font-size: 12px;
  color: var(--red);
}

.page-about .about-index-link:hover,
.page-about .about-index-link:focus-visible {
  border-color: var(--gold);
  transform: translateY(-2px);
}

.page-about .about-index-note {
  margin: 8px 0 0;
  font-size: 12px;
  line-height: 1.7;
  color: var(--slate);
}

/* 索引与当前章节联动（hash 定位时） */
.page-about:has(#sec-scope:target) .about-index-link[href="#sec-scope"],
.page-about:has(#sec-cards:target) .about-index-link[href="#sec-cards"],
.page-about:has(#sec-freeze:target) .about-index-link[href="#sec-freeze"],
.page-about:has(#sec-stop:target) .about-index-link[href="#sec-stop"],
.page-about:has(#sec-practice:target) .about-index-link[href="#sec-practice"],
.page-about:has(#sec-sichuan:target) .about-index-link[href="#sec-sichuan"] {
  background: var(--green);
  border-color: var(--green);
  color: var(--card);
  box-shadow: inset 4px 0 0 var(--gold);
}

.page-about:has(#sec-scope:target) .about-index-link[href="#sec-scope"] .about-index-num,
.page-about:has(#sec-cards:target) .about-index-link[href="#sec-cards"] .about-index-num,
.page-about:has(#sec-freeze:target) .about-index-link[href="#sec-freeze"] .about-index-num,
.page-about:has(#sec-stop:target) .about-index-link[href="#sec-stop"] .about-index-num,
.page-about:has(#sec-practice:target) .about-index-link[href="#sec-practice"] .about-index-num,
.page-about:has(#sec-sichuan:target) .about-index-link[href="#sec-sichuan"] .about-index-num {
  color: var(--gold);
}

/* ---------- 章节 ---------- */
.page-about .about-sec {
  position: relative;
  padding: 8px 0 46px;
  scroll-margin-top: 96px;
}

.page-about .about-sec + .about-sec {
  padding-top: 44px;
}

.page-about .about-sec + .about-sec::before {
  content: "";
  position: absolute;
  top: 4px;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--green) 0%, var(--red) 62%, var(--gold) 100%);
  transform: rotate(-0.7deg);
  opacity: 0.55;
}

.page-about .about-sec-num {
  margin: 0 0 4px;
  font-family: var(--font-num);
  font-size: 13px;
  letter-spacing: 0.24em;
  color: var(--gold);
}

.page-about .about-sec h2 {
  margin: 0 0 18px;
  font-family: var(--font-head);
  font-size: clamp(23px, 5.2vw, 32px);
  line-height: 1.28;
  font-weight: 900;
  color: var(--green);
}

.page-about .about-sec:target h2 {
  color: var(--red);
}

.page-about .about-sec .prose p {
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.9;
  color: var(--ink);
}

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

.page-about .about-inline-link {
  margin: 22px 0 0;
  padding-left: 14px;
  border-left: 4px solid var(--gold);
  font-size: 14px;
  line-height: 1.85;
  color: var(--slate);
}

.page-about .about-inline-link a {
  color: var(--red);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* 四条主线清单 */
.page-about .about-lines {
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--ink);
}

.page-about .about-line {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 4px 12px;
  padding: 14px 0;
  border-bottom: 1px solid var(--about-rule);
}

.page-about .about-line-code {
  grid-row: span 2;
  font-family: var(--font-num);
  font-size: 20px;
  font-weight: 700;
  color: var(--cyan);
  line-height: 1.2;
}

.page-about .about-line-name {
  font-family: var(--font-head);
  font-size: 17px;
  font-weight: 800;
  color: var(--ink);
}

.page-about .about-line-desc {
  font-size: 14px;
  line-height: 1.75;
  color: var(--slate);
}

/* 五步流程 */
.page-about .about-steps {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
  counter-reset: none;
}

.page-about .about-step {
  position: relative;
  padding: 16px 18px 18px;
  background: var(--card);
  border: 1px solid var(--about-rule);
  border-left: 4px solid var(--green);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);
  box-shadow: var(--shadow-card);
  transition: transform 0.22s var(--ease), border-color 0.22s var(--ease);
}

.page-about .about-step:hover {
  transform: translateY(-3px);
  border-left-color: var(--red);
}

.page-about .about-step-num {
  display: block;
  font-family: var(--font-num);
  font-size: 14px;
  letter-spacing: 0.14em;
  color: var(--gold);
}

.page-about .about-step-title {
  margin: 6px 0 8px;
  font-family: var(--font-head);
  font-size: 18px;
  font-weight: 800;
  color: var(--green);
}

.page-about .about-step-text {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--slate);
}

/* 图片 */
.page-about .about-figure {
  margin: 28px 0 0;
}

.page-about .about-media {
  border: 1px solid var(--ink);
  background: var(--green-deep);
  overflow: hidden;
}

.page-about .about-media img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  filter: saturate(0.92) contrast(1.04);
}

.page-about .about-figure .media-caption {
  margin: 10px 0 0;
  font-size: 13px;
  line-height: 1.75;
  color: var(--slate);
}

/* 折叠明细 */
.page-about .about-fold {
  margin-top: 24px;
  border: 1px solid var(--ink);
  border-top: 4px solid var(--red);
  background: var(--card);
}

.page-about .about-fold-trigger {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 18px;
  font-family: var(--font-head);
  font-size: 15px;
  font-weight: 800;
  color: var(--green);
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-fold-trigger::before {
  content: "＋";
  flex: 0 0 auto;
  font-family: var(--font-num);
  font-size: 15px;
  color: var(--red);
}

.page-about .about-fold[open] .about-fold-trigger::before {
  content: "－";
}

.page-about .about-fold-trigger:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}

.page-about .about-fold-body {
  padding: 0 18px 18px;
  border-top: 1px dashed var(--about-rule);
}

.page-about .about-fold-body p {
  margin: 14px 0 0;
  font-size: 15px;
  line-height: 1.9;
  color: var(--ink);
}

/* 分工计分板 */
.page-about .about-crew {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  margin-top: 26px;
}

.page-about .about-crew-item {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 2px;
  padding: 16px 18px;
  background: var(--green);
  color: var(--card);
  border: 1px solid var(--green-deep);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 16px), calc(100% - 16px) 100%, 0 100%);
}

.page-about .about-crew-num {
  font-family: var(--font-num);
  font-size: 46px;
  font-weight: 700;
  line-height: 1;
  color: var(--gold);
}

.page-about .about-crew-unit {
  color: var(--gold-hi);
}

.page-about .about-crew-item .scoreboard-label {
  font-size: 13px;
  line-height: 1.7;
  color: rgba(251, 246, 234, 0.86);
}

/* 印章行 */
.page-about .about-seal-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 22px;
}

.page-about .about-seal {
  font-family: var(--font-head);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.08em;
  padding: 7px 14px;
  border: 2px solid var(--red);
  border-radius: 999px;
  color: var(--red);
  background: rgba(179, 39, 45, 0.07);
}

.page-about .about-seal.is-errata {
  border-color: var(--cyan);
  color: var(--green);
  background: rgba(63, 214, 200, 0.14);
}

/* 维护清单 */
.page-about .about-maintain {
  margin: 24px 0 0;
  padding: 0;
  list-style: none;
  border-left: 2px solid var(--about-rule);
}

.page-about .about-maintain-item {
  position: relative;
  display: flex;
  gap: 14px;
  padding: 12px 0 12px 18px;
  border-bottom: 1px dashed var(--about-rule);
}

.page-about .about-maintain-item::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 20px;
  width: 8px;
  height: 2px;
  background: var(--gold);
}

.page-about .about-maintain-num {
  flex: 0 0 auto;
  font-family: var(--font-num);
  font-size: 13px;
  color: var(--red);
  padding-top: 3px;
}

.page-about .about-maintain-text {
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink);
}

/* 练习数据条 */
.page-about .about-practice-strip {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin-top: 26px;
  background: var(--green-deep);
  border: 1px solid var(--green-deep);
}

.page-about .about-practice-cell {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 18px 16px;
  background: var(--green);
}

.page-about .about-practice-num {
  font-family: var(--font-num);
  font-size: clamp(30px, 8vw, 44px);
  font-weight: 700;
  line-height: 1;
  color: var(--gold);
}

.page-about .about-practice-label {
  font-size: 13px;
  line-height: 1.6;
  color: rgba(251, 246, 234, 0.85);
}

/* 返回章节 */
.page-about .about-toplink {
  position: fixed;
  right: 14px;
  bottom: 14px;
  z-index: 20;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  background: var(--red);
  color: var(--card);
  font-family: var(--font-head);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-decoration: none;
  border: 1px solid var(--red-deep);
  clip-path: polygon(10px 0, 100% 0, 100% calc(100% - 10px), calc(100% - 10px) 100%, 0 100%, 0 10px);
  box-shadow: var(--shadow-lift);
  transition: transform 0.2s var(--ease), background-color 0.2s var(--ease);
}

.page-about .about-toplink:hover,
.page-about .about-toplink:focus-visible {
  transform: translateY(-2px);
  background: var(--green);
  border-color: var(--green-deep);
}

.page-about .about-toplink-mark {
  font-family: var(--font-num);
  color: var(--gold-hi);
}

/* ---------- 平板 ---------- */
@media (min-width: 720px) {
  .page-about .about-hero {
    padding: 28px 0 52px;
  }

  .page-about .about-hero::before {
    top: -180px;
    right: -34%;
    width: 96%;
    height: 520px;
  }

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

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

  .page-about .about-practice-strip {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-line {
    grid-template-columns: 44px minmax(0, 1fr) minmax(0, 1.6fr);
    align-items: baseline;
  }

  .page-about .about-line-code {
    grid-row: auto;
  }
}

/* ---------- 桌面：左侧固定章节索引 ---------- */
@media (min-width: 1024px) {
  .page-about .about-hero-grid {
    grid-template-columns: minmax(0, 1.42fr) minmax(280px, 0.58fr);
    gap: 48px;
    align-items: start;
  }

  .page-about .about-hero::before {
    top: -220px;
    right: -22%;
    width: 74%;
    height: 640px;
    transform: rotate(-9deg);
  }

  .page-about .about-layout {
    display: grid;
    grid-template-columns: var(--about-index-w) minmax(0, 1fr);
    gap: 54px;
    align-items: start;
    padding-top: 48px;
  }

  .page-about .about-index {
    position: sticky;
    top: 96px;
    margin-bottom: 0;
    padding: 18px 16px 16px;
    background: var(--card);
    border: 1px solid var(--ink);
    border-left: 5px solid var(--green);
    clip-path: polygon(0 0, 100% 0, 100% calc(100% - 18px), calc(100% - 18px) 100%, 0 100%);
    box-shadow: var(--shadow-card);
  }

  .page-about .about-index-list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
  }

  .page-about .about-index-item {
    border-bottom: 1px solid rgba(18, 58, 50, 0.14);
  }

  .page-about .about-index-item:last-child {
    border-bottom: none;
  }

  .page-about .about-index-link {
    width: 100%;
    padding: 11px 8px 11px 12px;
    border: none;
    border-left: 4px solid transparent;
    border-radius: 0;
    background: transparent;
    white-space: normal;
    box-sizing: border-box;
  }

  .page-about .about-index-link:hover,
  .page-about .about-index-link:focus-visible {
    border-left-color: var(--gold);
    transform: translateX(2px);
  }

  .page-about .about-index-text {
    font-size: 14px;
  }

  .page-about:has(#sec-scope:target) .about-index-link[href="#sec-scope"],
  .page-about:has(#sec-cards:target) .about-index-link[href="#sec-cards"],
  .page-about:has(#sec-freeze:target) .about-index-link[href="#sec-freeze"],
  .page-about:has(#sec-stop:target) .about-index-link[href="#sec-stop"],
  .page-about:has(#sec-practice:target) .about-index-link[href="#sec-practice"],
  .page-about:has(#sec-sichuan:target) .about-index-link[href="#sec-sichuan"] {
    background: transparent;
    border-left-color: var(--gold);
    box-shadow: none;
    color: var(--red);
  }

  .page-about:has(#sec-scope:target) .about-index-link[href="#sec-scope"] .about-index-num,
  .page-about:has(#sec-cards:target) .about-index-link[href="#sec-cards"] .about-index-num,
  .page-about:has(#sec-freeze:target) .about-index-link[href="#sec-freeze"] .about-index-num,
  .page-about:has(#sec-stop:target) .about-index-link[href="#sec-stop"] .about-index-num,
  .page-about:has(#sec-practice:target) .about-index-link[href="#sec-practice"] .about-index-num,
  .page-about:has(#sec-sichuan:target) .about-index-link[href="#sec-sichuan"] .about-index-num {
    color: var(--red);
    font-weight: 700;
  }

  /* 内容区左缘的年份刻度装饰线 */
  .page-about .about-body {
    position: relative;
  }

  .page-about .about-body::before {
    content: "";
    position: absolute;
    top: 8px;
    bottom: 40px;
    left: -26px;
    width: 1px;
    background: repeating-linear-gradient(180deg, var(--slate) 0 1px, transparent 1px 24px);
    opacity: 0.4;
    pointer-events: none;
  }

  .page-about .about-steps {
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 10px;
  }

  .page-about .about-step {
    padding: 14px 14px 16px;
  }

  .page-about .about-step-title {
    font-size: 16px;
  }

  .page-about .about-step-text {
    font-size: 13px;
  }

  .page-about .about-lines {
    margin-top: 30px;
  }

  .page-about .about-figure {
    margin-top: 32px;
  }

  .page-about .about-figure--wide .about-media {
    clip-path: polygon(0 0, 100% 0, 100% calc(100% - 22px), calc(100% - 22px) 100%, 0 100%);
  }

  .page-about .about-toplink {
    right: 26px;
    bottom: 26px;
  }
}

@media (min-width: 1280px) {
  .page-about {
    --about-index-w: 268px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-step,
  .page-about .about-index-link,
  .page-about .about-toplink {
    transition: none;
  }

  .page-about .about-step:hover,
  .page-about .about-index-link:hover,
  .page-about .about-toplink:hover {
    transform: none;
  }
}
<<<END>>>