.page-about {
  background: var(--paper);
  color: var(--ink);
}

.page-about .page-shell {
  padding-bottom: clamp(56px, 9vw, 104px);
}

/* ---------- 页头 ---------- */
.page-about .about-lead {
  padding-block: clamp(22px, 4vw, 40px) clamp(26px, 4vw, 44px);
  border-bottom: 1px solid var(--line);
  background-image: var(--grad-soft);
  background-repeat: no-repeat;
  background-size: 100% 1px;
  background-position: 0 100%;
}

.page-about .page-head__title {
  margin: 10px 0 16px;
  max-width: 18em;
  font-family: var(--font-head);
  font-size: clamp(32px, 6.2vw, 62px);
  font-weight: 800;
  line-height: 1.06;
  letter-spacing: -0.015em;
  color: var(--indigo);
}

.page-about .page-head__lead {
  max-width: 40em;
  margin: 0;
  font-size: clamp(16px, 1.9vw, 18px);
  line-height: 1.85;
  color: var(--ink);
}

.page-about .about-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 0;
  margin-top: clamp(22px, 3.5vw, 34px);
  border-top: 1px solid var(--line-soft);
  padding-top: 16px;
}

.page-about .about-meta__item {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding-right: clamp(16px, 3vw, 34px);
  margin-right: clamp(16px, 3vw, 34px);
  border-right: 1px solid var(--line);
}

.page-about .about-meta__item:last-child {
  border-right: 0;
  margin-right: 0;
  padding-right: 0;
}

.page-about .about-meta__num {
  font-size: clamp(20px, 2.6vw, 26px);
  font-weight: 700;
  color: var(--indigo);
  letter-spacing: 0.02em;
}

.page-about .about-meta__label {
  font-size: 13px;
  color: var(--steel);
}

/* ---------- 双栏骨架 ---------- */
.page-about .about-layout {
  display: grid;
  gap: clamp(22px, 4vw, 46px);
  padding-top: clamp(24px, 4vw, 44px);
}

/* ---------- 粘性章节索引 ---------- */
.page-about .about-index {
  border-top: 2px solid var(--indigo);
  padding-top: 12px;
}

.page-about .about-index__title {
  margin: 0 0 10px;
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--steel);
  text-transform: uppercase;
}

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

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

.page-about .about-index__link {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 8px 12px 8px 10px;
  border: 1px solid var(--line);
  border-radius: 2px;
  background: rgba(255, 255, 255, 0.6);
  color: var(--steel);
  font-size: 13px;
  line-height: 1.3;
  text-decoration: none;
  white-space: nowrap;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease), background-color 0.2s var(--ease);
}

.page-about .about-index__num {
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--indigo);
}

.page-about .about-index__link:hover,
.page-about .about-index__link:focus-visible {
  color: var(--indigo);
  border-color: var(--line-strong);
  background: var(--sky);
  outline: none;
}

.page-about .about-index__link[data-active="true"] {
  color: var(--indigo);
  border-color: var(--cyan);
  background: var(--sky);
  font-weight: 600;
}

.page-about .about-index__link[data-active="true"] .about-index__num {
  color: var(--coral-ink);
}

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

/* ---------- 章节通用 ---------- */
.page-about .about-section {
  padding-top: clamp(20px, 3vw, 30px);
  border-top: 1px solid var(--line);
}

.page-about .about-section + .about-section {
  margin-top: clamp(36px, 6vw, 64px);
}

.page-about .about-head {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 16px;
}

.page-about .about-head__num {
  flex: 0 0 auto;
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--cyan);
  padding: 2px 7px;
  border: 1px solid var(--line-strong);
  border-radius: 2px;
  background: var(--paper);
}

.page-about .about-head__title {
  margin: 0;
  font-family: var(--font-head);
  font-size: clamp(22px, 3.4vw, 36px);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--indigo);
}

.page-about .about-note {
  margin: 0 0 20px;
  max-width: 40em;
  font-size: 16px;
  line-height: 1.85;
  color: var(--steel);
}

.page-about .prose {
  max-width: 38em;
}

.page-about .prose p {
  margin: 0 0 14px;
  font-size: 16px;
  line-height: 1.9;
  color: var(--ink);
}

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

.page-about .prose a,
.page-about .about-linkline a {
  color: var(--coral-ink);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.page-about .prose a:hover,
.page-about .about-linkline a:hover {
  color: var(--indigo);
}

/* ---------- 章节 01：图文栏 ---------- */
.page-about .about-cols {
  display: grid;
  gap: clamp(20px, 3vw, 32px);
}

.page-about .about-figure {
  margin: 0;
  border: 1px solid var(--line);
  background: var(--sky);
  overflow: hidden;
}

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

.page-about .about-figure .media-frame__caption {
  padding: 9px 12px;
  border-top: 1px solid var(--line);
  background: var(--paper);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.05em;
  color: var(--steel);
}

.page-about .about-figure--band {
  margin-top: clamp(22px, 3.5vw, 34px);
}

.page-about .about-quote {
  margin: clamp(22px, 3.5vw, 32px) 0 0;
  padding: clamp(18px, 3vw, 28px);
  max-width: 34em;
  background: var(--grad-soft);
  border-left: 3px solid var(--cyan);
  font-family: var(--font-head);
  font-size: clamp(17px, 2.3vw, 22px);
  font-weight: 700;
  line-height: 1.6;
  color: var(--indigo);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 16px), calc(100% - 16px) 100%, 0 100%);
}

/* ---------- 章节 02：分工清单 ---------- */
.page-about .xlist {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .xlist__item {
  display: grid;
  grid-template-columns: 40px 1fr;
  gap: 4px 12px;
  padding: 18px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .xlist__num {
  grid-row: span 2;
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--cyan);
  padding-top: 3px;
}

.page-about .xlist__title {
  margin: 0;
  font-size: 17px;
  font-weight: 700;
  color: var(--ink);
}

.page-about .xlist__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--steel);
}

/* ---------- 章节 03：六类结构 ---------- */
.page-about .cats {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 2px solid var(--indigo);
}

.page-about .cats__item {
  display: grid;
  grid-template-columns: 42px 1fr;
  gap: 4px 12px;
  padding: 15px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .cats__num {
  grid-row: span 2;
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--indigo);
  padding-top: 3px;
}

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

.page-about .cats__desc {
  font-size: 15px;
  line-height: 1.8;
  color: var(--steel);
}

/* ---------- 章节 04：月度节奏 ---------- */
.page-about .cadence {
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 10px;
  counter-reset: none;
}

.page-about .cadence__step {
  padding: 16px 18px;
  background: var(--sand);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);
}

.page-about .cadence__num {
  display: block;
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--coral-ink);
}

.page-about .cadence__title {
  margin: 4px 0 6px;
  font-size: 16px;
  font-weight: 700;
  color: var(--indigo);
}

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

.page-about .about-linkline {
  margin: 20px 0 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--steel);
}

/* ---------- 章节 05：版本时间轴 ---------- */
.page-about .about-cols--versions {
  margin-top: clamp(18px, 3vw, 26px);
}

.page-about .timeline {
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .timeline__item {
  position: relative;
  padding: 2px 0 24px 26px;
  border-left: 1px solid var(--line-strong);
}

.page-about .timeline__item:last-child {
  padding-bottom: 0;
  border-left-color: transparent;
}

.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 8px;
  width: 9px;
  height: 9px;
  background: var(--paper);
  border: 2px solid var(--indigo);
  border-radius: 50%;
  transition: transform 0.2s var(--ease), border-color 0.2s var(--ease), background-color 0.2s var(--ease);
}

.page-about .timeline__item--now::before {
  border-color: var(--coral);
  background: var(--coral);
}

.page-about .timeline__ver {
  display: block;
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--steel);
}

.page-about .timeline__theme {
  margin: 3px 0 5px;
  font-size: 17px;
  font-weight: 700;
  line-height: 1.4;
  color: var(--ink);
  transition: color 0.2s var(--ease);
}

.page-about .timeline__sum {
  margin: 0;
  max-width: 30em;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--steel);
}

.page-about .timeline__item:hover::before,
.page-about .timeline__item:focus-within::before {
  transform: scale(1.35);
  border-color: var(--coral);
}

.page-about .timeline__item:hover .timeline__theme,
.page-about .timeline__item:focus-within .timeline__theme {
  color: var(--coral-ink);
}

.page-about .about-figure--tall {
  margin-top: 26px;
}

.page-about .about-prose--after {
  margin-top: clamp(20px, 3vw, 30px);
}

/* ---------- 章节 06：服务承诺 ---------- */
.page-about .promise {
  display: grid;
  gap: 14px;
  margin-top: 4px;
}

.page-about .promise__row {
  padding-top: 12px;
  border-top: 1px solid var(--line);
}

.page-about .promise__label {
  margin: 0 0 5px;
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--steel);
}

.page-about .promise__value {
  margin: 0 0 5px;
  font-size: 16px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--indigo);
  overflow-wrap: anywhere;
}

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

.page-about .nextsteps {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: clamp(24px, 4vw, 34px);
  padding-top: 20px;
  border-top: 1px solid var(--line-soft);
}

/* ---------- 断点 ---------- */
@media (min-width: 720px) {
  .page-about .cats__item {
    grid-template-columns: 52px 172px 1fr;
    align-items: baseline;
    gap: 0 14px;
  }

  .page-about .cats__num {
    grid-row: auto;
    padding-top: 0;
  }

  .page-about .xlist__item {
    grid-template-columns: 52px 1fr;
  }

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

  .page-about .promise {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 18px 28px;
  }
}

@media (min-width: 860px) {
  .page-about .about-cols {
    grid-template-columns: minmax(0, 1.12fr) minmax(0, 0.88fr);
    align-items: start;
  }

  .page-about .about-cols--versions {
    grid-template-columns: minmax(0, 1fr) minmax(0, 0.72fr);
    gap: clamp(24px, 4vw, 44px);
  }

  .page-about .about-figure--tall {
    margin-top: 0;
    position: sticky;
    top: 104px;
  }
}

@media (min-width: 960px) {
  .page-about .about-layout {
    grid-template-columns: 236px minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-index {
    position: sticky;
    top: 96px;
  }

  .page-about .about-index__list {
    display: block;
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .about-index__list > li + li {
    margin-top: 2px;
  }

  .page-about .about-index__link {
    display: flex;
    width: 100%;
    padding: 8px 8px;
    border: 0;
    border-left: 2px solid transparent;
    border-radius: 0;
    background: transparent;
    white-space: normal;
    font-size: 14px;
  }

  .page-about .about-index__link:hover,
  .page-about .about-index__link:focus-visible {
    background: var(--sky);
  }

  .page-about .about-index__link[data-active="true"] {
    border-left-color: var(--coral);
    background: transparent;
  }

  .page-about .about-index__coord {
    display: block;
    margin-top: 20px;
    padding: 14px;
    border: 1px solid var(--line);
    background: var(--sand);
    clip-path: polygon(0 0, 100% 0, 100% calc(100% - 12px), calc(100% - 12px) 100%, 0 100%);
  }

  .page-about .about-index__coord-label {
    margin: 0 0 6px;
    font-size: 10.5px;
    letter-spacing: 0.16em;
    color: var(--steel);
  }

  .page-about .about-index__coord-value {
    margin: 0 0 4px;
    font-size: 17px;
    font-weight: 700;
    color: var(--indigo);
    letter-spacing: 0.02em;
  }

  .page-about .about-index__coord-note {
    margin: 0;
    font-size: 12px;
    line-height: 1.6;
    color: var(--steel);
  }

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

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

@media (prefers-reduced-motion: reduce) {
  .page-about .about-index__link,
  .page-about .timeline__item::before,
  .page-about .timeline__theme {
    transition: none;
  }

  .page-about .timeline__item:hover::before,
  .page-about .timeline__item:focus-within::before {
    transform: none;
  }
}
<<<END>>>