.page-about {
  --about-rail-w: 172px;
  --about-gap: clamp(26px, 4vw, 48px);
}

.page-about .about-hero {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
  align-items: end;
  padding-block: clamp(22px, 4vw, 40px) clamp(26px, 4vw, 44px);
}

.page-about .about-hero__title {
  margin: 10px 0 16px;
  font-size: clamp(30px, 5.6vw, 52px);
  line-height: 1.1;
  letter-spacing: -0.01em;
}

.page-about .about-hero__lede {
  max-width: 34em;
  color: var(--paper);
}

.page-about .about-hero__sub {
  max-width: 34em;
  margin: 14px 0 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

.page-about .about-stats {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  border-top: 1px solid var(--line);
}

.page-about .about-stats__item {
  padding: 14px 10px 0 0;
  border-right: 1px solid var(--line);
}

.page-about .about-stats__item:last-child {
  border-right: 0;
}

.page-about .about-stats__num {
  display: block;
  font-size: clamp(24px, 4.4vw, 32px);
  font-weight: 600;
  line-height: 1;
  color: var(--cyan);
}

.page-about .about-stats__label {
  display: block;
  margin-top: 8px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--mist);
}

.page-about .about-hero__panel {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line);
  padding: 20px 18px 22px;
  background:
    radial-gradient(130% 100% at 12% 0%, rgba(14, 75, 82, 0.92), rgba(14, 75, 82, 0) 62%),
    radial-gradient(100% 90% at 100% 100%, rgba(62, 224, 212, 0.18), rgba(62, 224, 212, 0) 60%),
    var(--panel);
}

.page-about .about-hero__panel::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(31, 64, 84, 0.55) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(31, 64, 84, 0.55) 1px, transparent 1px);
  background-size: 32px 32px;
  -webkit-mask-image: linear-gradient(to bottom, #000, transparent 78%);
  mask-image: linear-gradient(to bottom, #000, transparent 78%);
}

.page-about .about-hero__cap {
  position: relative;
  margin: 0 0 14px;
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--mist);
}

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

.page-about .about-hero__ticks li {
  display: grid;
  grid-template-columns: 58px minmax(0, 1fr);
  gap: 12px;
  align-items: baseline;
  padding: 11px 0;
  border-top: 1px dashed rgba(31, 64, 84, 0.9);
  font-size: 14px;
  line-height: 1.6;
  color: var(--paper);
}

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

.page-about .about-hero__ticks b {
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--cyan);
}

/* 外壳：左刻度轨 + 右叙事列 */
.page-about .about-shell {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
  padding-bottom: clamp(48px, 7vw, 88px);
}

.page-about .about-rail {
  border-top: 1px solid var(--line);
  padding-top: 14px;
}

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

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 4px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .about-rail__list > li {
  flex: 0 0 auto;
}

.page-about .about-rail__link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 7px 10px;
  border: 1px solid var(--line);
  border-radius: 2px;
  text-decoration: none;
  color: var(--mist);
  white-space: nowrap;
  transition: color var(--t-fast) ease, border-color var(--t-fast) ease, background var(--t-fast) ease;
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--cyan-soft);
  border-color: var(--cyan);
  background: rgba(14, 75, 82, 0.4);
}

.page-about .about-rail__year {
  font-size: 13px;
  font-weight: 600;
  color: var(--cyan);
}

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

.page-about .about-rail__sect {
  margin-top: 14px;
}

.page-about .about-rail__cap {
  margin: 0 0 8px;
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--mist);
}

.page-about .about-rail__sublist {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
}

.page-about .about-rail__sublist a {
  font-size: 13px;
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--t-fast) ease, border-color var(--t-fast) ease;
}

.page-about .about-rail__sublist a:hover,
.page-about .about-rail__sublist a:focus-visible {
  color: var(--cyan-soft);
  border-bottom-color: var(--cyan);
}

/* 章节 */
.page-about .about-sec {
  padding-top: 24px;
  border-top: 1px solid var(--line);
  margin-top: var(--about-gap);
  scroll-margin-top: 84px;
}

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

.page-about .about-sec__head {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 14px;
}

.page-about .about-sec__no {
  flex: none;
  padding: 3px 7px;
  border: 1px solid var(--line);
  border-radius: 2px;
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--cyan);
}

.page-about .about-sec__head .section-title {
  margin: 0;
}

.page-about .about-sec__lead {
  max-width: 36em;
  margin: 0 0 14px;
  line-height: 1.8;
  color: var(--paper);
}

.page-about .about-note {
  max-width: 36em;
  margin: 16px 0 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .about-link {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(62, 224, 212, 0.35);
  transition: color var(--t-fast) ease, border-color var(--t-fast) ease;
}

.page-about .about-link:hover,
.page-about .about-link:focus-visible {
  color: var(--cyan-soft);
  border-bottom-color: var(--cyan-soft);
}

/* 三步 */
.page-about .about-steps {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-steps .step {
  background: var(--panel);
  padding: 16px;
}

.page-about .about-steps .step__num {
  display: inline-block;
  margin-bottom: 8px;
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--cyan);
}

.page-about .about-steps h3 {
  margin: 0 0 6px;
  font-size: var(--fs-h3);
}

.page-about .about-steps p {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--mist);
}

/* 时间线 */
.page-about .about-tl {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  position: relative;
}

.page-about .about-tl::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: var(--line);
}

.page-about .about-tl__item {
  position: relative;
  padding: 0 0 24px 32px;
  scroll-margin-top: 96px;
}

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

.page-about .about-tl__dot {
  position: absolute;
  left: 0;
  top: 5px;
  width: 15px;
  height: 15px;
  border: 1px solid var(--line);
  background: var(--ink);
}

.page-about .about-tl__item--amber .about-tl__dot {
  border-color: var(--amber-dim);
  background: var(--amber);
}

.page-about .about-tl__year {
  margin: 0 0 4px;
  font-size: 18px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--cyan);
}

.page-about .about-tl__item--amber .about-tl__year {
  color: var(--amber);
}

.page-about .about-tl__text {
  margin: 0;
  max-width: 34em;
  line-height: 1.8;
  color: var(--paper);
}

/* 版本对照 */
.page-about .about-compare {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin: 20px 0 22px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-compare__col {
  background: var(--layer);
  padding: 16px;
}

.page-about .about-compare__col--delta {
  background: rgba(138, 90, 22, 0.22);
}

.page-about .about-compare__col--hi {
  background: linear-gradient(180deg, rgba(14, 75, 82, 0.6), var(--layer));
}

.page-about .about-compare__ver {
  margin: 0;
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--mist);
}

.page-about .about-compare__num {
  display: block;
  margin: 8px 0 6px;
  font-size: clamp(30px, 6vw, 40px);
  font-weight: 600;
  line-height: 1;
  color: var(--paper);
}

.page-about .about-compare__col--delta .about-compare__num {
  color: var(--amber);
}

.page-about .about-compare__col--hi .about-compare__num {
  color: var(--cyan);
}

.page-about .about-compare__cap {
  margin: 0;
  font-size: 13px;
  color: var(--mist);
}

/* 增量条目 */
.page-about .about-delta {
  list-style: none;
  margin: 18px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-delta__item {
  background: var(--ink);
  padding: 16px;
}

.page-about .about-delta__tag {
  display: inline-block;
  margin-bottom: 9px;
  padding: 2px 7px;
  border: 1px solid var(--line);
  border-radius: 2px;
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--cyan-soft);
}

.page-about .about-delta__title {
  margin: 0 0 6px;
  font-size: 17px;
  line-height: 1.4;
}

.page-about .about-delta__text,
.page-about .about-delta__item p {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--mist);
}

/* 维护分工 */
.page-about .about-crew {
  list-style: none;
  margin: 20px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
}

.page-about .about-crew__box {
  border: 1px solid var(--line);
  border-left: 2px solid var(--cyan);
  background: var(--panel);
  padding: 16px;
}

.page-about .about-crew__box--amber {
  border-left-color: var(--amber);
}

.page-about .about-crew__no {
  display: block;
  margin-bottom: 8px;
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--mist);
}

.page-about .about-crew__box h3 {
  margin: 0 0 6px;
  font-size: var(--fs-h3);
}

.page-about .about-crew__box p {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--mist);
}

.page-about .about-facts {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

.page-about .about-facts li {
  display: grid;
  grid-template-columns: 92px minmax(0, 1fr);
  gap: 14px;
  align-items: baseline;
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
  line-height: 1.7;
  color: var(--mist);
}

.page-about .about-facts b {
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--paper);
  text-align: right;
}

/* 栏目节奏 */
.page-about .about-cols {
  list-style: none;
  margin: 20px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-col {
  background: var(--panel);
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.page-about .about-col__top {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
}

.page-about .about-col__name {
  margin: 0;
  font-size: var(--fs-h3);
}

.page-about .about-col__rate {
  flex: none;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--amber);
}

.page-about .about-col p {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--mist);
}

.page-about .about-col .about-link {
  align-self: flex-start;
  margin-top: 2px;
  font-size: 14px;
}

/* 折叠补充 */
.page-about .about-more {
  margin-top: 20px;
  border: 1px solid var(--line);
  background: var(--panel);
}

.page-about .about-more summary {
  padding: 12px 14px;
  font-size: 14px;
  color: var(--cyan-soft);
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-more summary::before {
  content: "+";
  display: inline-block;
  width: 16px;
  font-family: var(--font-mono);
  color: var(--cyan);
}

.page-about .about-more[open] summary::before {
  content: "–";
}

.page-about .about-more p {
  margin: 0;
  padding: 0 14px 14px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--mist);
}

/* 图片 */
.page-about .figure {
  margin: 22px 0 0;
}

.page-about .figure__frame {
  border: 1px solid var(--line);
  background: var(--panel);
  overflow: hidden;
}

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

.page-about .figure__cap {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--mist);
}

/* 断点 */
@media (min-width: 640px) {
  .page-about .about-compare {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

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

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

@media (min-width: 820px) {
  .page-about .about-crew {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 14px;
  }

  .page-about .about-facts li {
    grid-template-columns: 108px minmax(0, 1fr);
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
    gap: 46px;
  }
}

@media (min-width: 1024px) {
  .page-about .about-shell {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: 56px;
    align-items: start;
    margin-top: clamp(8px, 2vw, 20px);
  }

  .page-about .about-rail {
    position: sticky;
    top: 92px;
    border-top: 0;
    padding-top: 0;
  }

  .page-about .about-rail__spine {
    display: block;
    margin: 0 0 18px;
    padding-left: 2px;
    writing-mode: vertical-rl;
    font-size: 11px;
    letter-spacing: 0.24em;
    color: var(--mist);
  }

  .page-about .about-rail__list {
    display: block;
    overflow: visible;
    padding-bottom: 0;
    border-left: 1px solid var(--line);
  }

  .page-about .about-rail__list > li {
    display: block;
  }

  .page-about .about-rail__link {
    flex-direction: column;
    align-items: flex-start;
    gap: 2px;
    margin-left: -1px;
    padding: 8px 0 8px 14px;
    border: 0;
    border-left: 2px solid transparent;
    border-radius: 0;
    white-space: normal;
  }

  .page-about .about-rail__link:hover,
  .page-about .about-rail__link:focus-visible {
    background: transparent;
    border-left-color: var(--cyan);
    color: var(--cyan-soft);
  }

  .page-about .about-rail__sublist {
    display: block;
    padding-left: 14px;
  }

  .page-about .about-rail__sublist li {
    margin-bottom: 6px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail__link,
  .page-about .about-link,
  .page-about .about-rail__sublist a {
    transition: none;
  }
}
<<<END>>>