.page-about {
  --about-step-gap: 12px;
  --about-panel-lift: #143553;
}

.page-about .about-intro {
  padding-top: 26px;
}

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

.page-about .about-head {
  position: relative;
}

.page-about .about-head h1 {
  margin: 12px 0 0;
  font-family: var(--font-head);
  font-weight: 600;
  font-size: clamp(30px, 8vw, 60px);
  line-height: 1.03;
  letter-spacing: -.02em;
  color: var(--white);
  max-width: 15em;
}

.page-about .about-head h1::after {
  content: "";
  display: block;
  width: 84px;
  height: 4px;
  margin-top: 20px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--gold), var(--gold-deep));
}

.page-about .about-head .lede {
  margin-top: 20px;
  max-width: 60ch;
  color: var(--mist);
  line-height: 1.75;
}

.page-about .about-quick {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.page-about .about-quick li {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 14px 16px;
  border-radius: var(--r-md);
  background: var(--panel);
  border: 1px solid var(--line);
  transition: border-color .2s ease;
}

.page-about .about-quick li:hover {
  border-color: var(--line-strong);
}

.page-about .q-num {
  font-family: var(--font-num);
  font-size: clamp(22px, 5.2vw, 30px);
  line-height: 1;
  color: var(--gold);
  letter-spacing: -.01em;
}

.page-about .q-label {
  font-size: 13px;
  color: var(--mist);
}

/* 站点起点 */
.page-about .about-origin {
  display: grid;
  gap: 26px;
}

.page-about .about-origin-text h2 {
  margin: 0 0 14px;
  font-family: var(--font-head);
  font-size: clamp(22px, 4.8vw, 34px);
  line-height: 1.16;
  letter-spacing: -.01em;
  color: var(--white);
  max-width: 18em;
}

.page-about .about-origin-text p {
  margin: 0 0 14px;
  color: var(--mist);
  line-height: 1.75;
  max-width: 60ch;
}

.page-about .about-origin-figure {
  margin: 0;
}

/* 左侧目录 + 右侧正文 */
.page-about .about-layout {
  display: grid;
  gap: 34px;
}

.page-about .about-rail {
  border-top: 2px solid var(--gold);
  padding-top: 16px;
}

.page-about .about-rail-list {
  list-style: none;
  margin: 12px 0 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .about-rail-list a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 10px 4px 10px 0;
  color: var(--mist);
  text-decoration: none;
  font-size: 14.5px;
  border-bottom: 1px dashed var(--line);
  transition: color .18s ease, border-color .18s ease;
}

.page-about .about-rail-list a:hover,
.page-about .about-rail-list a:focus-visible {
  color: var(--white);
  border-bottom-color: var(--gold);
}

.page-about .about-rail-list .num {
  font-family: var(--font-num);
  font-size: 12px;
  color: var(--gold-deep);
}

.page-about .about-rail-note {
  margin: 18px 0 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--mist);
  padding: 12px 14px;
  border-radius: var(--r-sm);
  background: rgba(18, 48, 74, .6);
  border-left: 2px solid var(--gold-deep);
}

.page-about .about-rail-note a {
  color: var(--gold);
  text-decoration: underline;
  text-decoration-color: rgba(240, 160, 60, .45);
  text-underline-offset: 3px;
}

.page-about .about-rail-note a:hover {
  text-decoration-color: var(--gold);
}

.page-about .about-flow {
  display: grid;
  gap: 8px;
  min-width: 0;
}

.page-about .about-section {
  scroll-margin-top: 96px;
  padding-top: 32px;
  border-top: 1px solid var(--line);
}

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

.page-about .about-section h2 {
  margin: 0 0 14px;
  font-family: var(--font-head);
  font-size: clamp(21px, 4.4vw, 31px);
  line-height: 1.2;
  letter-spacing: -.01em;
  color: var(--white);
  max-width: 20em;
}

.page-about .about-section > p {
  margin: 0 0 14px;
  color: var(--mist);
  line-height: 1.75;
  max-width: 64ch;
}

.page-about .about-section > p a {
  color: var(--gold);
  text-decoration: underline;
  text-decoration-color: rgba(240, 160, 60, .4);
  text-underline-offset: 3px;
}

.page-about .about-section > p a:hover {
  text-decoration-color: var(--gold);
}

/* 字段定义折叠组 */
.page-about .about-fields {
  display: grid;
  gap: 10px;
  margin-top: 20px;
}

.page-about .about-fields .dim {
  border-radius: var(--r-md);
}

.page-about .about-fields .dim > summary {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 600;
  color: var(--white);
}

.page-about .field-tag {
  margin-left: auto;
  flex: none;
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: .02em;
  color: var(--gold-deep);
  border: 1px solid rgba(201, 122, 18, .45);
  border-radius: 999px;
  padding: 2px 10px;
}

.page-about .about-dl {
  margin: 14px 0 0;
  display: grid;
  gap: 6px;
}

.page-about .about-dl dt {
  font-family: var(--font-num);
  font-size: 13px;
  letter-spacing: .02em;
  color: var(--gold);
}

.page-about .about-dl dd {
  margin: 0 0 10px;
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--mist);
}

/* 三道流程步骤 */
.page-about .about-steps {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: var(--about-step-gap);
}

.page-about .about-step {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 14px;
  padding: 18px;
  border-radius: 22px;
  background: var(--panel);
  border: 1px solid var(--line);
  transition: border-color .2s ease, background-color .2s ease, transform .2s ease;
}

.page-about .about-step:hover,
.page-about .about-step:focus-within {
  border-color: rgba(240, 160, 60, .55);
  background: var(--about-panel-lift);
  transform: translateY(-2px);
}

.page-about .step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 30px;
  border-radius: 999px;
  background: rgba(240, 160, 60, .14);
  color: var(--gold);
  font-family: var(--font-num);
  font-size: 13px;
  letter-spacing: .04em;
}

.page-about .step-body {
  min-width: 0;
}

.page-about .step-name {
  margin: 0 0 6px;
  font-size: 17px;
  font-weight: 600;
  color: var(--white);
  line-height: 1.35;
}

.page-about .step-hint {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.72;
  color: var(--mist);
}

.page-about .about-process-figure {
  margin: 26px 0 0;
}

/* 版本迭代带 */
.page-about .version-track {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .version-item {
  position: relative;
  overflow: hidden;
  padding: 16px 22px;
  border-radius: var(--r-md);
  background: linear-gradient(100deg, rgba(18, 48, 74, .95), rgba(44, 59, 73, .5));
  border: 1px solid var(--line);
  transition: background-color .2s ease, border-color .2s ease;
}

.page-about .version-item::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 0;
  height: 0;
  border-top: 58px solid rgba(240, 160, 60, .16);
  border-left: 58px solid transparent;
  pointer-events: none;
}

.page-about .version-item:hover {
  border-color: var(--line-strong);
}

.page-about .version-item:nth-child(1) {
  border-left: 3px solid var(--gold-deep);
}

.page-about .version-item:nth-child(2) {
  border-left: 3px solid var(--gold);
}

.page-about .version-item:nth-child(3) {
  border-left: 3px solid var(--teal);
}

.page-about .version-item:nth-child(4) {
  border-left: 3px solid var(--teal);
}

.page-about .version-item:nth-child(5) {
  border-left: 3px solid var(--gold);
}

.page-about .version-year {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-num);
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--gold);
}

.page-about .version-name {
  margin: 0 0 5px;
  font-size: 16px;
  font-weight: 600;
  line-height: 1.4;
  color: var(--white);
}

.page-about .version-desc {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--mist);
  max-width: 58ch;
}

/* 覆盖范围 */
.page-about .about-scope {
  display: grid;
  gap: 24px;
  margin-top: 4px;
}

.page-about .about-scope-text p {
  margin: 0 0 14px;
  color: var(--mist);
  line-height: 1.75;
  max-width: 60ch;
}

.page-about .about-scope-figure {
  margin: 0;
}

/* 使用边界 */
.page-about .about-limits {
  margin-top: 6px;
  padding: 22px 22px 8px;
  border-radius: var(--r-lg);
  background: linear-gradient(135deg, rgba(201, 122, 18, .14), rgba(18, 48, 74, .55) 58%);
  border: 1px solid rgba(240, 160, 60, .28);
}

.page-about .about-limits p {
  margin: 0 0 14px;
  color: var(--mist);
  line-height: 1.75;
  font-size: 14.5px;
  max-width: 62ch;
}

.page-about .about-limits p:first-child {
  color: var(--white);
}

/* 收束区 */
.page-about .about-close {
  padding: 26px 24px;
  border-radius: var(--r-lg);
  background: var(--panel);
  border: 1px solid var(--line);
}

.page-about .about-close h2 {
  margin: 10px 0 12px;
  font-family: var(--font-head);
  font-size: clamp(20px, 4vw, 27px);
  line-height: 1.24;
  color: var(--white);
}

.page-about .about-close p {
  margin: 0;
  color: var(--mist);
  line-height: 1.75;
  max-width: 58ch;
}

.page-about .about-close-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}

/* 图片统一约束 */
.page-about img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* ---------- 平板与桌面 ---------- */
@media (min-width: 720px) {
  .page-about .about-quick {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-dl {
    grid-template-columns: 152px minmax(0, 1fr);
    column-gap: 20px;
    row-gap: 0;
  }

  .page-about .about-dl dt {
    padding: 9px 0;
    border-bottom: 1px dashed var(--line);
  }

  .page-about .about-dl dd {
    margin: 0;
    padding: 9px 0;
    border-bottom: 1px dashed var(--line);
  }

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

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

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

  .page-about .version-item:nth-child(5) {
    grid-column: 1 / -1;
  }
}

@media (min-width: 900px) {
  .page-about .about-origin {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
    gap: 46px;
    align-items: start;
  }

  .page-about .about-layout {
    grid-template-columns: 236px minmax(0, 1fr);
    gap: 54px;
  }

  .page-about .about-rail {
    position: sticky;
    top: 88px;
    align-self: start;
  }

  .page-about .about-flow {
    gap: 12px;
  }

  .page-about .about-section {
    padding-top: 38px;
  }

  .page-about .about-scope {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: 34px;
    align-items: start;
  }

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

  .page-about .version-item:nth-child(5) {
    grid-column: auto;
  }

  .page-about .about-close {
    padding: 34px 36px;
  }
}
<<<END>>>