/* ==========================================================================
   page-about · 平台概览
   移动端优先；桌面端为「左侧粘性章节索引 + 右侧内容流」的层叠目录结构
   ========================================================================== */

.page-about {
  --about-rule: rgba(36, 56, 47, .85);
  --about-glow: rgba(198, 255, 79, .14);
  background: var(--ink);
  color: var(--porcelain);
  display: block;
  overflow-x: hidden;
}

.page-about a {
  color: inherit;
}

/* ---------- 首屏 -------------------------------------------------------- */

.page-about .about-hero {
  position: relative;
  padding: calc(var(--header-h) + 48px) 0 56px;
  background:
    radial-gradient(130% 100% at 8% -18%, rgba(20, 49, 40, .96) 0%, rgba(7, 11, 9, 0) 64%),
    radial-gradient(90% 70% at 96% 6%, rgba(63, 224, 192, .07) 0%, rgba(7, 11, 9, 0) 58%),
    linear-gradient(180deg, var(--deep) 0%, var(--ink) 82%);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line) 16%, var(--line) 84%, transparent);
}

.page-about .about-hero .breadcrumbs {
  margin-bottom: 26px;
}

.page-about .about-hero__title {
  margin: 16px 0 0;
  max-width: 20ch;
  font-size: clamp(32px, 7.4vw, 72px);
  line-height: 1.04;
  letter-spacing: -0.02em;
  font-weight: 900;
  text-wrap: balance;
}

.page-about .about-hero__title .num {
  color: var(--lime);
}

.page-about .about-hero__lede {
  margin-top: 22px;
  max-width: 46em;
  color: var(--mist);
  font-size: 16px;
  line-height: 1.8;
}

/* 关键数字条 */

.page-about .about-hero__stats {
  margin: 38px 0 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  overflow: hidden;
}

.page-about .about-stat {
  position: relative;
  margin: 0;
  padding: 18px 18px 20px;
  background: var(--board);
}

.page-about .about-stat::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 2px;
  background: var(--lime);
}

.page-about .about-stat--amber::before {
  background: var(--amber);
}

.page-about .about-stat__label {
  margin: 0;
  font-size: 11px;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--mist);
}

.page-about .about-stat__value {
  margin: 8px 0 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(26px, 6vw, 40px);
  line-height: 1;
  font-weight: 700;
  color: var(--lime);
  letter-spacing: -0.02em;
}

.page-about .about-stat--amber .about-stat__value {
  color: var(--amber);
}

.page-about .about-stat__unit {
  margin-left: 2px;
  font-size: .48em;
  font-weight: 600;
  color: currentColor;
  opacity: .8;
}

.page-about .about-stat__note {
  margin: 8px 0 0;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--mist);
}

/* ---------- 主体网格 ---------------------------------------------------- */

.page-about .about-body {
  padding: 40px 0 72px;
  background:
    linear-gradient(180deg, var(--ink) 0%, var(--ink) 100%);
}

.page-about .about-body__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 34px;
}

/* ---------- 章节索引 ---------------------------------------------------- */

.page-about .about-index {
  min-width: 0;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--about-rule);
}

.page-about .about-index__list {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
}

.page-about .about-index__link {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 9px 12px 9px 14px;
  border-left: 2px solid var(--line);
  color: var(--mist);
  font-size: 13.5px;
  line-height: 1.5;
  text-decoration: none;
  transition: color .25s var(--ease), border-color .25s var(--ease), background-color .25s var(--ease);
}

.page-about .about-index__link:hover,
.page-about .about-index__link:focus-visible {
  color: var(--porcelain);
  border-left-color: var(--lime);
  background: rgba(198, 255, 79, .05);
}

.page-about .about-index__no {
  flex: none;
  font-size: 11px;
  letter-spacing: .06em;
  color: var(--lime);
  opacity: .75;
}

/* ---------- 内容流 ------------------------------------------------------ */

.page-about .about-flow {
  min-width: 0;
  display: grid;
  gap: clamp(52px, 8vw, 104px);
}

.page-about .about-sec {
  min-width: 0;
  scroll-margin-top: calc(var(--header-h) + 24px);
}

.page-about .about-sec__title {
  margin: 12px 0 0;
  font-family: var(--font-editorial);
  font-size: clamp(24px, 5.6vw, 38px);
  line-height: 1.26;
  letter-spacing: .005em;
  font-weight: 600;
  text-wrap: balance;
}

.page-about .about-sec__lede {
  margin-top: 18px;
  max-width: 44em;
  color: var(--mist);
  font-size: 15.5px;
  line-height: 1.8;
}

.page-about .about-sec__prose {
  margin-top: 20px;
}

.page-about .about-sec__prose p + p {
  margin-top: 16px;
}

.page-about .about-sec__tail {
  margin-top: 28px;
  padding-top: 20px;
  border-top: 1px solid var(--about-rule);
  color: var(--mist);
  font-size: 15px;
  line-height: 1.8;
}

.page-about .about-sec__tail a {
  color: var(--lime);
  text-decoration: none;
  border-bottom: 1px solid rgba(198, 255, 79, .35);
  transition: border-color .25s var(--ease);
}

.page-about .about-sec__tail a:hover,
.page-about .about-sec__tail a:focus-visible {
  border-bottom-color: var(--lime);
}

/* ---------- 01 起点：正文 + 竖图 ---------------------------------------- */

.page-about .about-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 28px;
}

.page-about .about-split__body {
  min-width: 0;
}

.page-about .about-split__media {
  position: relative;
  margin: 0;
}

.page-about .about-split__media img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--r-lg);
}

/* ---------- 02 三条线索 -------------------------------------------------- */

.page-about .about-threads {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  overflow: hidden;
}

.page-about .about-thread {
  position: relative;
  background: var(--board);
  padding: 26px 22px 28px;
}

.page-about .about-thread::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
  background: var(--lime);
}

.page-about .about-thread--score::before {
  background: var(--amber);
}

.page-about .about-thread--time::before {
  background: var(--cyan);
}

.page-about .about-thread__title {
  margin: 10px 0 0;
  font-size: 19px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--porcelain);
}

.page-about .about-thread__text {
  margin: 12px 0 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .about-thread__out {
  margin: 16px 0 0;
  padding-top: 14px;
  border-top: 1px dashed var(--about-rule);
  font-size: 13px;
  line-height: 1.7;
  color: rgba(243, 246, 241, .72);
}

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

.page-about .about-threads__map svg {
  display: block;
  width: 100%;
  height: auto;
}

.page-about .about-map__line {
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-dasharray: 5 11;
  opacity: .9;
}

.page-about .about-map__line--a { stroke: var(--lime); }
.page-about .about-map__line--b { stroke: var(--amber); }
.page-about .about-map__line--c { stroke: var(--cyan); }

.page-about .about-threads__caption {
  margin: 10px 0 0;
  font-size: 13px;
  color: var(--mist);
  letter-spacing: .01em;
}

/* ---------- 03 流程步骤 -------------------------------------------------- */

.page-about .about-steps {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
}

.page-about .about-step {
  position: relative;
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 16px;
  padding: 24px 0;
  border-top: 1px solid var(--about-rule);
}

.page-about .about-step--last {
  border-bottom: 1px solid var(--about-rule);
}

.page-about .about-step__node {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: var(--r-pill);
  background: var(--board);
  border: 1px solid var(--line);
  color: var(--lime);
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 14px;
  font-weight: 700;
  transition: border-color .25s var(--ease), box-shadow .25s var(--ease), background-color .25s var(--ease);
}

.page-about .about-step:hover .about-step__node,
.page-about .about-step:focus-within .about-step__node {
  border-color: var(--lime);
  background: rgba(198, 255, 79, .08);
  box-shadow: 0 0 0 4px var(--about-glow);
}

.page-about .about-step__body {
  min-width: 0;
}

.page-about .about-step__title {
  margin: 4px 0 0;
  font-size: 17px;
  line-height: 1.5;
  font-weight: 700;
  color: var(--porcelain);
}

.page-about .about-step__text {
  margin: 10px 0 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .about-step__out {
  margin: 12px 0 0;
  display: inline-block;
  padding: 5px 12px;
  border-radius: var(--r-pill);
  border: 1px solid var(--line);
  background: var(--deep);
  font-size: 12px;
  line-height: 1.6;
  letter-spacing: .02em;
  color: rgba(243, 246, 241, .78);
}

.page-about .about-pipeline__media {
  margin: 30px 0 0;
}

.page-about .about-pipeline__media img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--r-lg);
}

/* ---------- 04 覆盖范围 -------------------------------------------------- */

.page-about .about-meter {
  margin: 28px 0 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  overflow: hidden;
}

.page-about .about-meter__cell {
  position: relative;
  background: var(--deep);
  padding: 18px 16px 20px;
}

.page-about .about-meter__cell--amber::after,
.page-about .about-meter__cell--cyan::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
}

.page-about .about-meter__cell--amber::after { background: var(--amber); }
.page-about .about-meter__cell--cyan::after { background: var(--cyan); }

.page-about .about-meter__value {
  margin: 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(28px, 7vw, 44px);
  line-height: 1;
  font-weight: 700;
  color: var(--lime);
  letter-spacing: -0.03em;
}

.page-about .about-meter__cell--amber .about-meter__value { color: var(--amber); }
.page-about .about-meter__cell--cyan .about-meter__value { color: var(--cyan); }

.page-about .about-meter__unit {
  margin-left: 2px;
  font-size: .42em;
  font-weight: 600;
  opacity: .82;
}

.page-about .about-meter__label {
  margin: 10px 0 0;
  font-size: 12.5px;
  letter-spacing: .04em;
  color: var(--mist);
}

.page-about .about-projects {
  margin-top: 26px;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  overflow: hidden;
}

.page-about .about-project {
  background: var(--board);
  padding: 22px 20px 24px;
}

.page-about .about-project__title {
  margin: 0;
  font-size: 16px;
  font-weight: 700;
  color: var(--lime);
  letter-spacing: .01em;
}

.page-about .about-project__text {
  margin: 10px 0 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--mist);
}

/* ---------- 05 团队 ------------------------------------------------------ */

.page-about .about-team {
  margin-top: 28px;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 14px;
}

.page-about .about-team__card {
  position: relative;
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: linear-gradient(150deg, var(--board) 0%, var(--deep) 100%);
  padding: 20px 18px 22px;
  overflow: hidden;
}

.page-about .about-team__card::before {
  content: "";
  position: absolute;
  top: -30px;
  right: -30px;
  width: 96px;
  height: 96px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(198, 255, 79, .16) 0%, rgba(198, 255, 79, 0) 70%);
}

.page-about .about-team__card--amber::before {
  background: radial-gradient(circle, rgba(255, 155, 49, .18) 0%, rgba(255, 155, 49, 0) 70%);
}

.page-about .about-team__value {
  margin: 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(30px, 8vw, 46px);
  line-height: 1;
  font-weight: 700;
  color: var(--lime);
  letter-spacing: -0.03em;
}

.page-about .about-team__card--amber .about-team__value {
  color: var(--amber);
}

.page-about .about-team__unit {
  margin-left: 3px;
  font-size: .38em;
  font-weight: 600;
  opacity: .8;
}

.page-about .about-team__label {
  margin: 12px 0 0;
  font-size: 13px;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--porcelain);
}

.page-about .about-team__note {
  margin: 8px 0 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--mist);
}

/* ---------- 06 使用场景 -------------------------------------------------- */

.page-about .about-users {
  margin-top: 28px;
  display: grid;
  gap: 18px;
}

.page-about .about-user {
  position: relative;
  padding: 22px 20px 24px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--lime);
  border-radius: var(--r-md);
  background: rgba(20, 49, 40, .48);
}

.page-about .about-user:nth-child(2) { border-left-color: var(--amber); }
.page-about .about-user:nth-child(3) { border-left-color: var(--cyan); }
.page-about .about-user:nth-child(4) { border-left-color: rgba(152, 167, 158, .7); }

.page-about .about-user__title {
  margin: 10px 0 0;
  font-family: var(--font-editorial);
  font-size: 18px;
  line-height: 1.45;
  font-weight: 600;
  color: var(--porcelain);
}

.page-about .about-user__text {
  margin: 10px 0 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--mist);
}

/* ---------- 07 服务信息 -------------------------------------------------- */

.page-about .about-reach {
  margin: 26px 0 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  overflow: hidden;
}

.page-about .about-reach__item {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 6px;
  background: var(--deep);
  padding: 16px 18px;
}

.page-about .about-reach__key {
  font-size: 11px;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--mist);
}

.page-about .about-reach__val {
  margin: 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 15px;
  line-height: 1.6;
  color: var(--porcelain);
  word-break: break-word;
}

.page-about .about-reach__val a {
  color: var(--lime);
  text-decoration: none;
  border-bottom: 1px solid rgba(198, 255, 79, .32);
  transition: border-color .25s var(--ease);
}

.page-about .about-reach__val a:hover,
.page-about .about-reach__val a:focus-visible {
  border-bottom-color: var(--lime);
}

.page-about .about-reach__actions {
  margin-top: 26px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 收尾区 ------------------------------------------------------ */

.page-about .about-next {
  position: relative;
  padding: 56px 0 72px;
  background:
    linear-gradient(135deg, var(--deep) 0%, var(--board) 52%, var(--ink) 100%);
  border-top: 1px solid var(--line);
  overflow: hidden;
}

.page-about .about-next::before {
  content: "";
  position: absolute;
  top: -40%;
  left: -10%;
  width: 60%;
  height: 180%;
  background: linear-gradient(110deg, rgba(198, 255, 79, .07) 0%, rgba(198, 255, 79, 0) 62%);
  transform: rotate(-14deg);
  pointer-events: none;
}

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

.page-about .about-next__title {
  margin: 12px 0 0;
  font-family: var(--font-editorial);
  font-size: clamp(24px, 5.6vw, 38px);
  line-height: 1.28;
  font-weight: 600;
  text-wrap: balance;
}

.page-about .about-next__text {
  margin: 16px 0 0;
  max-width: 42em;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .about-next__actions {
  margin-top: 26px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .about-next__links {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px 22px;
}

.page-about .about-next__links a {
  font-size: 13.5px;
  letter-spacing: .04em;
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color .25s var(--ease), border-color .25s var(--ease);
}

.page-about .about-next__links a:hover,
.page-about .about-next__links a:focus-visible {
  color: var(--lime);
  border-bottom-color: var(--lime);
}

/* ---------- 回到顶部胶囊 ------------------------------------------------ */

.page-about .about-totop {
  position: fixed;
  right: clamp(14px, 3vw, 30px);
  bottom: clamp(14px, 3vw, 30px);
  z-index: 30;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 9px 16px;
  border-radius: var(--r-pill);
  border: 1px solid var(--line);
  background: rgba(13, 33, 28, .9);
  backdrop-filter: blur(8px);
  color: var(--porcelain);
  font-size: 12.5px;
  letter-spacing: .06em;
  text-decoration: none;
  transition: border-color .25s var(--ease), background-color .25s var(--ease), color .25s var(--ease);
}

.page-about .about-totop:hover,
.page-about .about-totop:focus-visible {
  border-color: var(--lime);
  background: rgba(20, 49, 40, .96);
  color: var(--lime);
}

.page-about .about-totop__arrow {
  font-size: 14px;
  line-height: 1;
}

/* ---------- 焦点可见性 -------------------------------------------------- */

.page-about .about-index__link:focus-visible,
.page-about .about-totop:focus-visible,
.page-about .about-sec__tail a:focus-visible,
.page-about .about-reach__val a:focus-visible,
.page-about .about-next__links a:focus-visible {
  outline: 2px solid var(--lime);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ==========================================================================
   响应式
   ========================================================================== */

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

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

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

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

@media (min-width: 860px) {
  .page-about .about-split {
    grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr);
    align-items: start;
    gap: clamp(28px, 4vw, 56px);
  }

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

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

@media (min-width: 1024px) {
  .page-about .about-body {
    padding: 56px 0 96px;
  }

  .page-about .about-body__grid {
    grid-template-columns: minmax(196px, 232px) minmax(0, 1fr);
    gap: clamp(40px, 5.5vw, 84px);
    align-items: start;
  }

  .page-about .about-index {
    position: sticky;
    top: calc(var(--header-h) + 28px);
    padding-bottom: 0;
    border-bottom: 0;
  }

  .page-about .about-index__list {
    border-left: 1px solid var(--about-rule);
    margin-left: 2px;
  }

  .page-about .about-index__link {
    border-left: 2px solid transparent;
    margin-left: -1px;
  }

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

  .page-about .about-hero {
    padding: calc(var(--header-h) + 72px) 0 80px;
  }

  .page-about .about-hero__lede {
    font-size: 17px;
  }
}

@media (min-width: 1200px) {
  .page-about .about-users {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

/* ---------- 动效偏好 ---------------------------------------------------- */

@media (prefers-reduced-motion: reduce) {
  .page-about .about-index__link,
  .page-about .about-step__node,
  .page-about .about-totop,
  .page-about .about-sec__tail a,
  .page-about .about-reach__val a,
  .page-about .about-next__links a {
    transition: none;
  }
}
<<<END>>>