.page-about {
  --about-strip: 46px;
  --about-gap: 20px;
  background: linear-gradient(180deg, var(--c-night-2) 0%, var(--c-night) 520px);
  color: var(--c-paper);
  overflow-x: hidden;
}

/* ---------- 面包屑 ---------- */
.page-about .breadcrumb {
  padding-top: calc(var(--unit) * 3);
}

/* ---------- 开篇 ---------- */
.page-about .about-hero {
  position: relative;
}

.page-about .about-hero__media {
  position: relative;
  overflow: hidden;
  border-bottom: 1px solid var(--c-rule);
}

.page-about .about-hero__media::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(4, 18, 14, 0.30) 0%, rgba(4, 18, 14, 0.62) 46%, var(--c-night) 100%);
}

.page-about .about-hero__img {
  display: block;
  width: 100%;
  height: clamp(220px, 38vw, 460px);
  object-fit: cover;
  filter: saturate(0.82) contrast(1.04);
}

.page-about .about-hero__inner {
  position: relative;
  z-index: 2;
  margin-top: -108px;
  padding-bottom: calc(var(--unit) * 3);
}

.page-about .about-hero__eyebrow {
  margin: 0 0 14px;
  font-size: 12.5px;
  letter-spacing: 0.22em;
  color: var(--c-cyan);
  text-transform: uppercase;
}

.page-about .about-hero__title {
  margin: 0 0 18px;
  max-width: 19ch;
  font-size: clamp(30px, 5.6vw, 54px);
  font-weight: 900;
  line-height: 1.14;
  letter-spacing: -0.015em;
}

.page-about .about-hero__title em {
  display: block;
  font-style: normal;
  color: var(--c-cyan);
}

.page-about .about-hero__lede {
  margin: 0;
  max-width: 60ch;
  font-size: 16px;
  line-height: 1.7;
  color: var(--c-paper);
}

/* ---------- 主体布局 ---------- */
.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: calc(var(--unit) * 6);
  padding: calc(var(--unit) * 6) 0 calc(var(--unit) * 10);
}

.page-about .about-stream {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

/* ---------- 章节 ---------- */
.page-about .about-chapter {
  position: relative;
  padding: calc(var(--unit) * 6) 0;
  border-top: 1px solid var(--c-rule);
  scroll-margin-top: 96px;
}

.page-about .about-chapter:first-child {
  border-top: 0;
  padding-top: calc(var(--unit) * 2);
}

.page-about .about-chapter__marker {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin: 0 0 14px;
}

.page-about .about-chapter__marker-num {
  font-size: 13px;
  letter-spacing: 0.16em;
  color: var(--c-copper);
}

.page-about .about-chapter__marker-note {
  font-size: 12.5px;
  letter-spacing: 0.2em;
  color: var(--c-muted);
}

.page-about .about-chapter__title {
  margin: 0 0 16px;
  font-size: clamp(24px, 3.6vw, 34px);
  font-weight: 900;
  line-height: 1.24;
  letter-spacing: -0.012em;
}

.page-about .about-chapter p {
  margin: 0 0 14px;
  max-width: 62ch;
  font-size: 15.5px;
  line-height: 1.72;
  color: var(--c-paper);
}

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

.page-about .about-chapter a {
  color: var(--c-cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(47, 230, 208, 0.35);
}

.page-about .about-chapter a:hover {
  border-bottom-color: var(--c-cyan);
}

/* ---------- 时间轴 ---------- */
.page-about .about-timeline {
  position: relative;
  margin: calc(var(--unit) * 4) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 12px;
  bottom: 12px;
  width: 1px;
  background: linear-gradient(180deg, var(--c-copper) 0%, rgba(185, 145, 90, 0.10) 100%);
}

.page-about .about-timeline__item {
  position: relative;
  padding: 0 0 calc(var(--unit) * 3.25) 34px;
}

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

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 5px;
  width: 15px;
  height: 15px;
  border: 1px solid var(--c-copper);
  border-radius: 50%;
  background: var(--c-night);
  transition: background-color 0.25s var(--ease), box-shadow 0.25s var(--ease);
}

.page-about .about-timeline__item:hover::before,
.page-about .about-timeline__item:focus-within::before {
  background: var(--c-copper);
  box-shadow: 0 0 0 5px rgba(185, 145, 90, 0.16);
}

.page-about .about-timeline__year {
  display: block;
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--c-copper);
}

.page-about .about-timeline__title {
  margin: 5px 0 6px;
  font-size: 17px;
  font-weight: 800;
  line-height: 1.4;
}

.page-about .about-timeline__text {
  margin: 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.66;
  color: var(--c-muted);
}

/* ---------- 图 ---------- */
.page-about .about-figure {
  margin: calc(var(--unit) * 5) 0 0;
  padding: 0;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--c-rule);
  border-radius: var(--radius);
}

.page-about .about-figure--tall {
  max-width: 300px;
}

.page-about .about-figure .media__caption {
  margin-top: 10px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--c-muted);
}

/* ---------- 指标条 ---------- */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: calc(var(--unit) * 3) 0 calc(var(--unit) * 4);
  background: var(--c-rule);
  border: 1px solid var(--c-rule);
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about .about-stat {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 18px 16px;
  background: var(--c-layer);
}

.page-about .about-stat__num {
  font-size: 34px;
  font-weight: 500;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--c-cyan);
}

.page-about .about-stat__num--lime {
  color: var(--c-lime);
}

.page-about .about-stat__num--copper {
  color: var(--c-copper);
}

.page-about .about-stat__unit {
  margin-left: 5px;
  font-size: 0.44em;
  font-weight: 500;
  color: var(--c-muted);
}

.page-about .about-stat__label {
  font-size: 13px;
  line-height: 1.45;
  color: var(--c-muted);
}

/* ---------- 流程步骤 ---------- */
.page-about .about-steps {
  position: relative;
  margin: calc(var(--unit) * 3.5) 0 0;
  padding-left: 24px;
}

.page-about .about-steps::before {
  content: "";
  position: absolute;
  left: 0;
  top: 16px;
  bottom: 16px;
  width: 1px;
  background: linear-gradient(180deg, var(--c-cyan) 0%, rgba(47, 230, 208, 0.08) 100%);
}

.page-about .about-step {
  position: relative;
  border-top: 1px solid var(--c-rule);
}

.page-about .about-step::before {
  content: "";
  position: absolute;
  left: -24px;
  top: 27px;
  width: 7px;
  height: 7px;
  border: 1px solid var(--c-cyan);
  border-radius: 50%;
  background: var(--c-night);
}

.page-about .about-step__summary {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 17px 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-step__summary:focus-visible {
  outline: 1px solid var(--c-cyan);
  outline-offset: 4px;
}

.page-about .about-step__idx {
  font-size: 12.5px;
  letter-spacing: 0.14em;
  color: var(--c-copper);
}

.page-about .about-step__name {
  font-size: 17px;
  font-weight: 800;
}

.page-about .about-step__hint {
  margin-left: auto;
  font-size: 12.5px;
  color: var(--c-muted);
}

.page-about .about-step__hint::after {
  content: "展开";
}

.page-about .about-step[open] .about-step__hint {
  color: var(--c-cyan);
}

.page-about .about-step[open] .about-step__hint::after {
  content: "收起";
}

.page-about .about-step__panel {
  padding: 0 0 18px;
}

.page-about .about-step__panel p {
  margin: 0;
  max-width: 60ch;
  font-size: 15px;
  line-height: 1.68;
  color: var(--c-muted);
}

/* ---------- 引用与版本 ---------- */
.page-about .about-assure {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: calc(var(--unit) * 3.5) 0 0;
  padding: 0;
  list-style: none;
  background: var(--c-rule);
  border: 1px solid var(--c-rule);
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about .about-assure__item {
  padding: 20px 18px 22px;
  background: var(--c-layer);
}

.page-about .about-assure__title {
  margin: 0 0 8px;
  font-size: 16px;
  font-weight: 800;
  line-height: 1.45;
  color: var(--c-paper);
}

.page-about .about-assure__item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.66;
  color: var(--c-muted);
}

.page-about .about-version {
  display: inline-flex;
  align-items: baseline;
  gap: 12px;
  margin: calc(var(--unit) * 3.5) 0 0;
  padding: 12px 18px;
  border: 1px solid rgba(185, 145, 90, 0.4);
  border-radius: var(--radius);
  background: rgba(185, 145, 90, 0.06);
}

.page-about .about-version__key {
  font-size: 12.5px;
  letter-spacing: 0.16em;
  color: var(--c-muted);
}

.page-about .about-version__val {
  font-size: 22px;
  font-weight: 500;
  color: var(--c-copper);
}

/* ---------- 客户 ---------- */
.page-about .about-clients {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  margin: calc(var(--unit) * 4) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-client {
  padding: 18px 18px 20px;
  border-left: 2px solid var(--c-cyan);
  border-radius: var(--radius);
  background: linear-gradient(180deg, var(--c-glass-strong) 0%, rgba(255, 255, 255, 0.02) 100%);
}

.page-about .about-client:nth-child(2) {
  border-left-color: var(--c-lime);
}

.page-about .about-client:nth-child(3) {
  border-left-color: var(--c-copper);
}

.page-about .about-client:nth-child(4) {
  border-left-color: var(--c-cool);
}

.page-about .about-client__name {
  margin: 0 0 8px;
  font-size: 16px;
  font-weight: 800;
  line-height: 1.4;
}

.page-about .about-client__text {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.68;
  color: var(--c-muted);
}

/* ---------- 报告 ---------- */
.page-about .about-reports {
  display: flex;
  gap: 14px;
  margin: calc(var(--unit) * 3.5) 0 0;
  padding: 0 0 12px;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch;
}

.page-about .about-report {
  flex: 0 0 76%;
  scroll-snap-align: start;
  display: flex;
  flex-direction: column;
  gap: 10px;
  min-height: 206px;
  padding: 20px 18px 22px;
  border: 1px solid var(--c-rule);
  border-top: 2px solid var(--c-cyan);
  border-radius: var(--radius);
  background: var(--c-layer);
}

.page-about .about-report--winter {
  border-top-color: var(--c-cool);
}

.page-about .about-report--sprint {
  border-top-color: var(--c-amber);
}

.page-about .about-report--final {
  border-top-color: var(--c-copper);
}

.page-about .about-report__idx {
  font-size: 12.5px;
  letter-spacing: 0.18em;
  color: var(--c-muted);
}

.page-about .about-report__name {
  margin: 0;
  font-size: 18px;
  font-weight: 800;
  line-height: 1.35;
}

.page-about .about-report__text {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.66;
  color: var(--c-muted);
}

.page-about .about-more {
  margin-top: calc(var(--unit) * 3);
  font-size: 14.5px;
  color: var(--c-muted);
}

/* ---------- 联系 ---------- */
.page-about .about-chapter--cta {
  padding-bottom: calc(var(--unit) * 4);
}

.page-about .about-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: calc(var(--unit) * 3);
}

/* ---------- 章节索引 ---------- */
.page-about .about-index {
  min-width: 0;
}

.page-about .about-index__label {
  margin: 0 0 12px;
  font-size: 12.5px;
  letter-spacing: 0.2em;
  color: var(--c-muted);
}

.page-about .about-index__list {
  display: flex;
  gap: 10px;
  margin: 0;
  padding: 0 0 6px;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .about-index__item {
  flex: 0 0 auto;
}

.page-about .about-index__link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 13px;
  font-size: 13px;
  color: var(--c-muted);
  text-decoration: none;
  white-space: nowrap;
  border: 1px solid var(--c-rule);
  border-radius: 999px;
  background: var(--c-glass);
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.page-about .about-index__link .mono {
  font-size: 11.5px;
  color: var(--c-copper);
}

.page-about .about-index__link:hover,
.page-about .about-index__link:focus-visible {
  color: var(--c-cyan);
  border-color: rgba(47, 230, 208, 0.45);
}

/* ---------- 中屏 ---------- */
@media (min-width: 640px) {
  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .page-about .about-report {
    flex: 0 0 46%;
  }
}

@media (min-width: 820px) {
  .page-about .about-reports {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .about-report {
    width: auto;
    min-height: 224px;
  }
}

/* ---------- 桌面 ---------- */
@media (min-width: 900px) {
  .page-about .about-chapter {
    padding: calc(var(--unit) * 7) 0 calc(var(--unit) * 7) 106px;
  }

  .page-about .about-chapter:first-child {
    padding-top: calc(var(--unit) * 2);
  }

  .page-about .about-chapter__marker {
    position: absolute;
    left: 6px;
    top: calc(var(--unit) * 7 + 12px);
    display: block;
    margin: 0;
    writing-mode: vertical-rl;
    text-orientation: mixed;
  }

  .page-about .about-chapter:first-child .about-chapter__marker {
    top: calc(var(--unit) * 2 + 12px);
  }

  .page-about .about-chapter__marker-num {
    font-size: 15px;
    letter-spacing: 0.2em;
  }

  .page-about .about-chapter__marker-note {
    font-size: 12.5px;
    letter-spacing: 0.24em;
  }

  .page-about .about-figure--tall {
    max-width: 320px;
  }
}

@media (min-width: 1000px) {
  .page-about .about-layout {
    grid-template-columns: minmax(0, 1fr) 176px;
    gap: clamp(36px, 5vw, 76px);
    padding-top: calc(var(--unit) * 8);
  }

  .page-about .about-index {
    position: sticky;
    top: 104px;
    align-self: start;
  }

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

  .page-about .about-index__item + .about-index__item {
    margin-top: 4px;
  }

  .page-about .about-index__link {
    display: flex;
    justify-content: flex-start;
    padding: 9px 12px;
    border-radius: var(--radius);
    border-color: transparent;
    background: transparent;
  }

  .page-about .about-index__link:hover,
  .page-about .about-index__link:focus-visible {
    background: var(--c-glass);
    border-color: rgba(47, 230, 208, 0.35);
  }
}

@media (min-width: 1180px) {
  .page-about .about-assure {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-clients {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 14px;
  }
}

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