.page-about {
  --rail-w: 230px;
  background: var(--snow);
  color: var(--ink-900);
  overflow-x: clip;
}

/* ---------- 页内章节导航 ---------- */
.page-about .about-rail {
  display: none;
}

@media (min-width: 1280px) {
  .page-about .about-rail {
    display: flex;
    align-items: stretch;
    gap: 12px;
    position: fixed;
    right: 18px;
    top: 50%;
    transform: translateY(-50%);
    z-index: 30;
  }
}

.page-about .about-rail__track {
  order: 2;
  position: relative;
  display: block;
  width: 3px;
  border-radius: 3px;
  background: var(--gray-200);
  overflow: hidden;
}

.page-about .about-rail__fill {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 0;
  background: var(--red);
  transition: height 140ms linear;
}

.page-about .about-rail__list {
  order: 1;
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
  text-align: right;
}

.page-about .about-rail__link {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .06em;
  color: var(--gray-500);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  padding-bottom: 1px;
  transition: color 200ms var(--ease), border-color 200ms var(--ease);
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--red);
  border-bottom-color: var(--red);
}

/* ---------- 首屏声明 ---------- */
.page-about .about-intro {
  padding-top: calc(var(--shell-h) + 44px);
  padding-bottom: 56px;
  background:
    linear-gradient(102deg, var(--frost) 0%, var(--frost) 46%, var(--snow) 46%, var(--snow) 100%);
}

.page-about .about-intro .breadcrumb {
  margin-bottom: 28px;
}

.page-about .about-intro__grid {
  display: grid;
  gap: 24px;
}

@media (min-width: 880px) {
  .page-about .about-intro__grid {
    grid-template-columns: 5fr 7fr;
    gap: 56px;
    align-items: start;
  }
}

.page-about .about-intro__title {
  margin: 12px 0 0;
  position: relative;
}

.page-about .about-intro__title::after {
  content: "";
  display: block;
  width: 84px;
  height: 6px;
  margin-top: 22px;
  background: linear-gradient(90deg, var(--red) 0%, var(--red) 62%, var(--blue) 62%, var(--blue) 100%);
}

.page-about .about-intro__body p {
  max-width: 34em;
  margin: 0 0 18px;
}

.page-about .about-intro__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 28px;
  margin: 26px 0 0;
  padding: 18px 0 0;
  list-style: none;
  border-top: 1px solid var(--gray-200);
  font-size: 14px;
  color: var(--gray-500);
}

.page-about .about-intro__facts .num {
  font-size: 17px;
  font-weight: 700;
  color: var(--ink-900);
}

/* ---------- 中轴结构 ---------- */
.page-about .about-axis {
  position: relative;
  max-width: calc(var(--maxw) + var(--gut) * 2);
  margin: 0 auto;
  padding: 0 var(--gut);
}

@media (min-width: 980px) {
  .page-about .about-axis::before {
    content: "";
    position: absolute;
    top: 8px;
    bottom: 8px;
    left: calc(var(--gut) + var(--rail-w) - 1px);
    width: 2px;
    background: linear-gradient(180deg,
      var(--red) 0%,
      var(--red) 18%,
      var(--blue) 52%,
      var(--line-500) 100%);
    opacity: .42;
  }
}

.page-about .about-block {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  padding: 48px 0;
  border-top: 1px solid var(--gray-200);
}

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

@media (min-width: 980px) {
  .page-about .about-block {
    grid-template-columns: var(--rail-w) minmax(0, 1fr);
    gap: 56px;
    padding: 64px 0;
  }
}

.page-about .about-block__rail {
  position: relative;
  padding-right: 0;
}

@media (min-width: 980px) {
  .page-about .about-block__rail {
    padding-right: 26px;
  }
}

.page-about .about-node {
  display: none;
}

@media (min-width: 980px) {
  .page-about .about-node {
    display: block;
    position: absolute;
    right: -10px;
    top: 6px;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    border: 2px solid var(--gold);
    background: var(--snow);
    box-shadow: 0 0 0 5px var(--snow);
  }

  .page-about .about-node--gold {
    border-color: var(--red);
  }
}

.page-about .about-block__kicker {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--gray-500);
}

.page-about .about-block__title {
  margin: 0;
  font-size: 22px;
  line-height: 1.35;
  font-weight: 800;
  color: var(--ink-900);
}

@media (min-width: 980px) {
  .page-about .about-block__title {
    font-size: 26px;
  }
}

.page-about .about-block__body > p {
  max-width: 34em;
  margin: 0 0 18px;
  font-size: 16.5px;
  line-height: 1.78;
  color: var(--ink-900);
}

.page-about .about-block__lead {
  font-size: 19px;
  font-weight: 500;
  line-height: 1.7;
  color: var(--ink-900);
}

.page-about .about-block__media {
  margin: 28px 0 0;
}

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

/* ---------- 三条取舍标准 ---------- */
.page-about .about-criteria {
  display: grid;
  gap: 16px;
  margin-top: 30px;
}

.page-about .about-criterion {
  position: relative;
  width: 100%;
  padding: 22px 22px 20px;
  background: var(--ink-900);
  color: var(--frost);
  clip-path: polygon(0 0, calc(100% - 22px) 0, 100% 22px, 100% 100%, 22px 100%, 0 calc(100% - 22px));
}

@media (min-width: 760px) {
  .page-about .about-criterion {
    padding: 26px 28px 24px;
  }

  .page-about .about-criterion:nth-child(2) {
    width: calc(100% - 12px);
  }

  .page-about .about-criterion:nth-child(3) {
    width: calc(100% - 24px);
  }
}

.page-about .about-criterion__head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--line-500);
}

.page-about .about-criterion__index {
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--red);
  font-weight: 700;
}

.page-about .about-criterion__name {
  margin: 0;
  font-size: 20px;
  font-weight: 800;
  color: var(--snow);
}

.page-about .about-criterion__pair {
  display: grid;
  gap: 18px;
  margin-top: 18px;
}

@media (min-width: 620px) {
  .page-about .about-criterion__pair {
    grid-template-columns: 1fr 1fr;
    gap: 26px;
  }
}

.page-about .about-criterion__cell p {
  margin: 10px 0 0;
  font-size: 15px;
  line-height: 1.72;
  color: var(--frost);
}

.page-about .about-criterion__cell--counter p {
  color: #A9AEBC;
}

.page-about .about-criterion__cell--counter {
  padding-left: 16px;
  border-left: 2px solid var(--line-500);
}

@media (max-width: 619px) {
  .page-about .about-criterion__cell--counter {
    padding-left: 14px;
  }
}

/* ---------- 版本时间轴 ---------- */
.page-about .about-versions {
  margin-top: 34px;
}

.page-about .about-versions__tablist {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  border-bottom: 1px solid var(--gray-200);
}

.page-about .about-versions .tab {
  appearance: none;
  border: 0;
  background: transparent;
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 700;
  color: var(--gray-500);
  padding: 12px 18px;
  min-height: 44px;
  cursor: pointer;
  border-bottom: 3px solid transparent;
  transition: color 200ms var(--ease), border-color 200ms var(--ease);
}

.page-about .about-versions .tab[aria-selected="true"] {
  color: var(--ink-900);
  border-bottom-color: var(--red);
}

.page-about .about-versions .tab:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 2px;
}

.page-about .about-versions__panel {
  margin-top: 8px;
}

.page-about .about-versions__panel[hidden] {
  display: none;
}

.page-about .about-version {
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
  padding: 22px 0;
  border-bottom: 1px solid var(--gray-200);
}

@media (min-width: 640px) {
  .page-about .about-version {
    grid-template-columns: 92px minmax(0, 1fr);
    gap: 24px;
    align-items: start;
    padding: 24px 0;
  }
}

.page-about .about-version__no {
  font-size: 24px;
  font-weight: 700;
  letter-spacing: -.02em;
  color: var(--red);
  line-height: 1;
}

.page-about .about-version__name {
  margin: 0 0 8px;
  font-size: 18px;
  font-weight: 800;
  color: var(--ink-900);
}

.page-about .about-version__body p {
  max-width: 36em;
  margin: 0;
  font-size: 15.5px;
  line-height: 1.75;
  color: var(--gray-500);
}

/* ---------- 团队与分工 ---------- */
.page-about .about-team {
  margin-top: 30px;
  display: grid;
  gap: 26px;
}

@media (min-width: 900px) {
  .page-about .about-team {
    grid-template-columns: 7fr 5fr;
    gap: 42px;
    align-items: start;
  }
}

.page-about .about-team__roles {
  display: grid;
  gap: 0;
}

.page-about .about-role {
  display: grid;
  grid-template-columns: 1fr;
  gap: 4px;
  padding: 20px 0 20px 18px;
  border-left: 3px solid var(--gray-200);
  transition: border-color 240ms var(--ease), transform 240ms var(--ease);
}

.page-about .about-role:hover,
.page-about .about-role:focus-within {
  border-left-color: var(--red);
  transform: translateX(4px);
}

.page-about .about-role__count {
  font-size: 30px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--blue);
}

.page-about .about-role__name {
  margin: 6px 0 0;
  font-size: 17px;
  font-weight: 800;
  color: var(--ink-900);
}

.page-about .about-role p {
  max-width: 32em;
  margin: 6px 0 0;
  font-size: 15px;
  line-height: 1.72;
  color: var(--gray-500);
}

.page-about .about-team__media {
  margin: 0;
}

.page-about .about-team__note {
  max-width: 44em;
  margin: 28px 0 0;
  padding: 18px 20px;
  background: var(--frost);
  border-left: 3px solid var(--red);
  font-size: 15.5px;
  line-height: 1.75;
  color: var(--ink-900);
}

/* ---------- 更新节奏 ---------- */
.page-about .about-cadence {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .about-cadence__item {
  display: grid;
  grid-template-columns: 1fr;
  gap: 8px;
  padding: 22px 0;
  border-bottom: 1px solid var(--gray-200);
}

@media (min-width: 660px) {
  .page-about .about-cadence__item {
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 28px;
    align-items: baseline;
  }
}

.page-about .about-cadence__freq {
  display: inline-block;
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -.02em;
  color: var(--ink-900);
  background: linear-gradient(180deg, transparent 62%, rgba(229, 23, 58, .22) 62%);
  padding: 0 2px 2px;
}

.page-about .about-cadence__text h3 {
  margin: 0 0 8px;
  font-size: 17px;
  font-weight: 800;
  color: var(--ink-900);
}

.page-about .about-cadence__text p {
  max-width: 38em;
  margin: 0;
  font-size: 15.5px;
  line-height: 1.75;
  color: var(--gray-500);
}

/* ---------- 协作与资质 ---------- */
.page-about .about-credits {
  margin: 30px 0 0;
  display: grid;
  gap: 0;
}

.page-about .about-credits__row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
  padding: 20px 0;
  border-bottom: 1px solid var(--gray-200);
}

@media (min-width: 700px) {
  .page-about .about-credits__row {
    grid-template-columns: 150px minmax(0, 1fr);
    gap: 32px;
    align-items: baseline;
  }
}

.page-about .about-credits__row dt {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--gold);
  font-weight: 700;
}

.page-about .about-credits__row dd {
  margin: 0;
  max-width: 40em;
  font-size: 15.5px;
  line-height: 1.75;
  color: var(--ink-900);
}

/* ---------- 收束带 ---------- */
.page-about .about-close__panel {
  position: relative;
  max-width: 760px;
  padding-left: 22px;
  border-left: 6px solid var(--red);
}

.page-about .about-close__title {
  margin: 10px 0 14px;
}

.page-about .about-close__text {
  max-width: 34em;
  margin: 0 0 26px;
  font-size: 16px;
  line-height: 1.78;
  color: var(--gray-500);
}

.page-about .about-close__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

@media (max-width: 480px) {
  .page-about .about-close__panel {
    padding-left: 16px;
    border-left-width: 4px;
  }

  .page-about .about-close__links .btn {
    width: 100%;
    text-align: center;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail__fill,
  .page-about .about-role,
  .page-about .about-versions .tab,
  .page-about .about-rail__link {
    transition: none;
  }
}
<<<END>>>