.page-about {
  background: var(--by-ink);
  color: var(--by-text);
  overflow-x: hidden;
}

/* ---------- 页首 ---------- */
.page-about .about-head {
  padding-top: 28px;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--by-line);
  background:
    radial-gradient(120% 140% at 92% 0%, rgba(38, 239, 208, .10) 0%, transparent 58%),
    linear-gradient(180deg, rgba(18, 58, 48, .55) 0%, rgba(4, 16, 13, 0) 100%);
}

.page-about .about-head__inner {
  display: grid;
  gap: 14px;
}

.page-about .about-head .by-breadcrumb {
  margin-bottom: 4px;
}

.page-about .about-head__title {
  max-width: 20ch;
  font-size: clamp(30px, 7vw, 62px);
  line-height: 1.1;
  letter-spacing: -.01em;
  margin: 0;
}

.page-about .about-head__lede {
  max-width: 60ch;
  margin: 0;
  color: var(--by-silver);
}

/* ---------- 图片带 ---------- */
.page-about .about-visual {
  padding: 0;
}

.page-about .about-visual .by-wrap {
  margin-block: 22px;
}

.page-about .about-visual--mid .by-figure {
  max-width: 620px;
  margin-inline: auto;
}

.page-about .about-visual--end .by-wrap {
  margin-bottom: 8px;
}

.page-about .about-visual .by-figure {
  margin: 0;
}

/* ---------- 出发点 ---------- */
.page-about .about-intro {
  border-bottom: 1px solid var(--by-line);
}

.page-about .about-intro__grid {
  display: grid;
  gap: 18px;
}

.page-about .about-intro__lead .by-title {
  margin: 6px 0 0;
  font-size: clamp(24px, 5vw, 40px);
  line-height: 1.16;
}

.page-about .about-intro__body p {
  margin: 0 0 12px;
  max-width: 68ch;
  color: var(--by-silver);
  line-height: 1.8;
}

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

/* ---------- 阶段演进 ---------- */
.page-about .about-journey {
  position: relative;
}

.page-about .about-journey .by-title {
  margin: 6px 0 0;
  max-width: 26ch;
  font-size: clamp(24px, 5vw, 40px);
  line-height: 1.16;
}

.page-about .about-stages {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  border-top: 1px solid var(--by-line);
}

.page-about .about-stage {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  column-gap: 14px;
  padding: 20px 0;
  border-bottom: 1px solid var(--by-line);
  position: relative;
}

.page-about .about-stage::after {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 0;
  height: 1px;
  background: var(--by-orange);
  transition: width .4s ease;
}

.page-about .about-stage.is-visible::after {
  width: 64px;
}

.page-about .about-stage__index {
  color: var(--by-orange);
  font-size: 13px;
  letter-spacing: .1em;
  padding-top: 5px;
}

.page-about .about-stage__title {
  margin: 0 0 8px;
  font-size: 18px;
  font-weight: 600;
  line-height: 1.34;
  color: var(--by-text);
}

.page-about .about-stage__text {
  margin: 0;
  max-width: 64ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--by-silver);
}

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

/* ---------- 现在可用能力 ---------- */
.page-about .about-now {
  border-top: 1px solid var(--by-line);
  background:
    linear-gradient(180deg, rgba(13, 43, 37, .55) 0%, rgba(4, 16, 13, 0) 100%);
}

.page-about .about-now .by-title {
  margin: 6px 0 10px;
  max-width: 24ch;
  font-size: clamp(24px, 5vw, 40px);
  line-height: 1.16;
}

.page-about .about-now__lede {
  max-width: 62ch;
  color: var(--by-silver);
}

.page-about .about-caps {
  margin-top: 26px;
  display: grid;
  gap: 14px;
}

.page-about .about-cap {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 18px 18px 20px;
  border: 1px solid var(--by-line);
  border-radius: 2px;
  background: linear-gradient(180deg, rgba(7, 26, 22, .78) 0%, rgba(4, 16, 13, .55) 100%);
  box-shadow: 0 1px 0 rgba(230, 240, 238, .03);
}

.page-about .about-cap .by-badge {
  align-self: flex-start;
}

.page-about .about-cap__title {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
  line-height: 1.34;
}

.page-about .about-cap__text {
  margin: 0;
  flex: 1 1 auto;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--by-silver);
}

.page-about .about-cap .by-link {
  margin-top: 4px;
  font-size: 14px;
  align-self: flex-start;
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  border-top: 1px solid var(--by-line-strong);
}

.page-about .about-next__inner {
  display: grid;
  gap: 12px;
}

.page-about .about-next .by-title {
  margin: 4px 0 0;
  max-width: 24ch;
  font-size: clamp(22px, 4.6vw, 34px);
  line-height: 1.18;
}

.page-about .about-next__lede {
  max-width: 60ch;
  margin: 0;
  color: var(--by-silver);
}

.page-about .about-next__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 6px;
}

.page-about .about-next__actions .by-btn {
  min-width: 152px;
  justify-content: center;
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .about-head {
    padding-top: 52px;
    padding-bottom: 46px;
  }

  .page-about .about-intro__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.25fr);
    column-gap: 40px;
    align-items: start;
  }

  .page-about .about-stage {
    grid-template-columns: 96px minmax(0, 1fr);
    column-gap: 26px;
    padding: 26px 0;
  }

  .page-about .about-stage__index {
    font-size: 14px;
    padding-top: 6px;
  }

  .page-about .about-stage__title {
    font-size: 21px;
  }

  .page-about .about-caps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px;
  }

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

@media (min-width: 1040px) {
  .page-about .about-caps {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-stage {
    grid-template-columns: 132px minmax(0, 1fr);
    column-gap: 40px;
  }

  .page-about .about-next__inner {
    align-items: end;
  }

  .page-about .about-next__actions {
    margin-top: 10px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-stage::after {
    width: 64px;
    transition: none;
  }
}