.page-about {
  --about-line: 1px solid var(--hair);
  --about-gap: clamp(18px, 3vw, 30px);
  display: block;
  color: var(--mist);
  padding-bottom: clamp(48px, 8vw, 96px);
}

.page-about .about-topbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 20px;
  padding-top: clamp(18px, 3vw, 32px);
}

.page-about .about-filecode {
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--tide);
}

/* ---------- 封面 ---------- */
.page-about .about-cover {
  display: grid;
  gap: clamp(28px, 4vw, 52px);
  padding-block: clamp(26px, 5vw, 56px) clamp(36px, 6vw, 74px);
}

.page-about .about-cover__lead {
  display: flex;
  flex-direction: column;
  gap: 18px;
  min-width: 0;
}

.page-about .about-cover h1 {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 900;
  font-size: clamp(2.2rem, 8.4vw, 4.4rem);
  line-height: 1.04;
  letter-spacing: -0.02em;
  color: var(--mist);
}

.page-about .about-cover__accent {
  background: linear-gradient(96deg, var(--neon) 0%, var(--neon-soft) 62%, var(--gold) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.page-about .about-cover__lede {
  margin: 0;
  max-width: 46ch;
  font-size: clamp(1rem, 2vw, 1.08rem);
  line-height: 1.85;
  color: var(--fog);
}

.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  border-top: var(--about-line);
  padding-top: 16px;
  margin-top: 4px;
}

.page-about .about-stats__item {
  display: flex;
  flex-direction: column;
  gap: 4px;
  min-width: 0;
}

.page-about .about-stats__num {
  font-family: var(--font-mono);
  font-size: clamp(1.3rem, 4.6vw, 1.85rem);
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--neon);
}

.page-about .about-stats__item:nth-child(3) .about-stats__num {
  color: var(--gold);
}

.page-about .about-stats__label {
  font-size: 12px;
  line-height: 1.5;
  color: var(--fog);
}

.page-about .about-cover__aside {
  display: flex;
  flex-direction: column;
  gap: clamp(16px, 2.6vw, 24px);
  min-width: 0;
}

/* 三层目录索引 */
.page-about .about-index {
  border: var(--about-line);
  border-radius: var(--radius);
  background: linear-gradient(180deg, rgba(15, 42, 61, 0.82) 0%, rgba(8, 26, 41, 0.9) 100%);
  padding: 14px 14px 8px;
  box-shadow: 0 1px 0 rgba(53, 224, 208, 0.12) inset;
}

.page-about .about-index__title {
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--tide);
  margin: 0 0 10px 6px;
}

.page-about .about-index__group + .about-index__group {
  border-top: var(--about-line);
  padding-top: 6px;
  margin-top: 4px;
}

.page-about .about-index__link {
  display: grid;
  grid-template-columns: 32px minmax(0, 1fr);
  align-items: start;
  gap: 10px;
  padding: 9px 8px;
  border-radius: var(--radius-sm);
  text-decoration: none;
  color: var(--mist);
  transition: background-color 0.22s var(--ease), transform 0.22s var(--ease);
}

.page-about .about-index__link:hover,
.page-about .about-index__link:focus-visible {
  background: rgba(53, 224, 208, 0.09);
  transform: translateX(3px);
}

.page-about .about-index__idx {
  font-size: 12px;
  font-weight: 600;
  color: var(--neon);
  line-height: 1.6;
}

.page-about .about-index__body {
  display: block;
  min-width: 0;
}

.page-about .about-index__label {
  display: block;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 15px;
  line-height: 1.5;
}

.page-about .about-index__keys {
  display: block;
  margin-top: 2px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--tide);
}

.page-about .about-cover__media {
  border: var(--about-line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--sea-800);
}

.page-about .about-cover__media img {
  display: block;
  width: 100%;
  height: 100%;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

/* ---------- 章节通用 ---------- */
.page-about .about-section {
  padding-block: clamp(34px, 6vw, 68px);
  border-top: var(--about-line);
}

.page-about .about-split {
  display: grid;
  gap: var(--about-gap);
}

.page-about .about-section__head {
  display: flex;
  flex-direction: column;
  gap: 12px;
  min-width: 0;
}

.page-about .about-section__num {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.16em;
  color: var(--neon);
}

.page-about .about-section__num::after {
  content: "";
  width: 34px;
  height: 1px;
  background: linear-gradient(90deg, var(--neon), transparent);
}

.page-about .about-section__title {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: clamp(1.5rem, 4.6vw, 2.4rem);
  line-height: 1.24;
  letter-spacing: -0.01em;
  color: var(--mist);
}

.page-about .about-section__lede {
  margin: 0;
  max-width: 52ch;
  color: var(--fog);
  line-height: 1.8;
  font-size: 15px;
}

.page-about .about-section__body {
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.page-about .about-section__body > p {
  margin: 0;
  color: var(--fog);
  line-height: 1.85;
}

.page-about .about-section__head--wide {
  margin-bottom: var(--about-gap);
}

/* ---------- 引用 ---------- */
.page-about .about-quote {
  margin: clamp(26px, 4vw, 44px) 0 0;
  padding: 6px 0 6px 20px;
  border-left: 2px solid var(--gold);
  max-width: 62ch;
}

.page-about .about-quote blockquote {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: clamp(1.15rem, 3.4vw, 1.6rem);
  line-height: 1.5;
  color: var(--mist);
}

.page-about .about-quote__src {
  display: block;
  margin-top: 10px;
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--gold);
}

/* ---------- 三条主线 ---------- */
.page-about .about-lines {
  display: grid;
  gap: 14px;
}

.page-about .about-line {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 22px 18px 18px;
  background: var(--sea-800);
  border: var(--about-line);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color 0.24s var(--ease), background-color 0.24s var(--ease);
}

.page-about .about-line::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 2px;
  background: linear-gradient(90deg, var(--neon) 0%, rgba(53, 224, 208, 0) 78%);
}

.page-about .about-line:nth-child(2)::before {
  background: linear-gradient(90deg, var(--neon-soft) 0%, rgba(124, 242, 230, 0) 78%);
}

.page-about .about-line:nth-child(3)::before {
  background: linear-gradient(90deg, var(--gold) 0%, rgba(242, 184, 75, 0) 78%);
}

.page-about .about-line:hover {
  border-color: rgba(53, 224, 208, 0.42);
  background: var(--sea-700);
}

.page-about .about-line__num {
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--tide);
}

.page-about .about-line__title {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: 1.05rem;
  line-height: 1.5;
  color: var(--mist);
}

.page-about .about-line__text {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--fog);
  flex: 1;
}

.page-about .about-line__link {
  align-self: flex-start;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--neon);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 224, 208, 0.4);
  padding-bottom: 2px;
}

.page-about .about-line__link:hover,
.page-about .about-line__link:focus-visible {
  color: var(--gold-bright);
  border-bottom-color: var(--gold);
}

.page-about .about-note {
  margin: var(--about-gap) 0 0;
  padding: 14px 16px;
  border: 1px dashed var(--hair);
  border-radius: var(--radius-sm);
  font-size: 13.5px;
  line-height: 1.8;
  color: var(--fog);
  background: rgba(15, 42, 61, 0.42);
}

.page-about .about-note a {
  color: var(--neon);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 224, 208, 0.4);
}

.page-about .about-note a:hover {
  color: var(--gold-bright);
}

.page-about .about-note--flat {
  border-style: solid;
  border-color: var(--hair);
  margin-top: 20px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.02em;
  color: var(--tide);
  background: transparent;
}

/* ---------- 步骤 ---------- */
.page-about .about-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .about-step {
  position: relative;
  padding: 0 0 20px 24px;
  border-left: 1px solid var(--hair);
}

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

.page-about .about-step::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 7px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--neon);
  box-shadow: 0 0 0 4px rgba(53, 224, 208, 0.13);
}

.page-about .about-step:nth-child(2)::before {
  background: var(--gold);
  box-shadow: 0 0 0 4px rgba(242, 184, 75, 0.13);
}

.page-about .about-step:nth-child(3)::before {
  background: var(--tide);
  box-shadow: 0 0 0 4px rgba(30, 111, 140, 0.16);
}

.page-about .about-step__title {
  margin: 0 0 6px;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: 1rem;
  color: var(--mist);
}

.page-about .about-step__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--fog);
}

/* ---------- 阶段轨道 ---------- */
.page-about .about-track-figure {
  margin: 0 0 clamp(22px, 3.5vw, 34px);
  border: var(--about-line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--sea-800);
}

.page-about .about-track-figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 2 / 1;
  object-fit: cover;
  opacity: 0.9;
}

.page-about .about-track {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .about-stage {
  position: relative;
  padding: 0 0 22px 22px;
  border-left: 1px solid var(--hair);
  display: flex;
  flex-direction: column;
  gap: 6px;
}

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

.page-about .about-stage::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 6px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--sea-900);
  border: 1px solid var(--neon);
  transition: background-color 0.24s var(--ease), transform 0.24s var(--ease);
}

.page-about .about-stage:last-child::before {
  background: var(--gold);
  border-color: var(--gold);
}

.page-about .about-stage:hover::before {
  transform: scale(1.35);
  background: var(--neon);
}

.page-about .about-stage:last-child:hover::before {
  background: var(--gold-bright);
}

.page-about .about-stage__phase {
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--tide);
}

.page-about .about-stage:last-child .about-stage__phase {
  color: var(--gold);
}

.page-about .about-stage__title {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: 1rem;
  line-height: 1.45;
  color: var(--mist);
}

.page-about .about-stage__text {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.75;
  color: var(--fog);
}

/* ---------- 生态 ---------- */
.page-about .about-eco {
  display: grid;
  gap: var(--about-gap);
  align-items: start;
}

.page-about .about-eco__text {
  display: flex;
  flex-direction: column;
  gap: 14px;
  min-width: 0;
}

.page-about .about-eco__text > p {
  margin: 0;
  color: var(--fog);
  line-height: 1.85;
}

.page-about .about-eco__figure {
  margin: 0;
  border: var(--about-line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--sea-800);
}

.page-about .about-eco__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 4 / 3;
  object-fit: cover;
}

.page-about .about-eco__list {
  display: grid;
  gap: 12px;
  border-top: var(--about-line);
  padding-top: 16px;
}

.page-about .about-eco__list--tight {
  border-top: 0;
  padding-top: 0;
  margin-top: 4px;
}

.page-about .about-eco__item {
  display: flex;
  flex-direction: column;
  gap: 3px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--fog);
  padding-left: 14px;
  border-left: 2px solid rgba(53, 224, 208, 0.28);
}

.page-about .about-eco__strong {
  font-family: var(--font-head);
  font-weight: 800;
  font-size: 14.5px;
  color: var(--mist);
}

/* ---------- 收尾 CTA ---------- */
.page-about .about-cta {
  padding-top: clamp(10px, 2vw, 20px);
}

.page-about .about-cta__inner {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding: clamp(24px, 4.5vw, 46px);
  border: 1px solid rgba(53, 224, 208, 0.28);
  border-radius: var(--radius);
  background:
    repeating-linear-gradient(90deg, rgba(53, 224, 208, 0.06) 0 1px, transparent 1px 64px),
    repeating-linear-gradient(0deg, rgba(53, 224, 208, 0.06) 0 1px, transparent 1px 64px),
    linear-gradient(150deg, var(--sea-800) 0%, var(--sea-850) 60%, rgba(30, 111, 140, 0.22) 100%);
  overflow: hidden;
}

.page-about .about-cta__inner h2 {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 900;
  font-size: clamp(1.4rem, 4.4vw, 2.1rem);
  line-height: 1.3;
  color: var(--mist);
}

.page-about .about-cta__inner p {
  margin: 0;
  max-width: 60ch;
  color: var(--fog);
  line-height: 1.8;
  font-size: 15px;
}

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

/* ---------- 平板与桌面 ---------- */
@media (min-width: 760px) {
  .page-about .about-lines {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

@media (min-width: 900px) {
  .page-about .about-cover {
    grid-template-columns: minmax(0, 1.06fr) minmax(0, 0.94fr);
    align-items: start;
  }

  .page-about .about-split {
    grid-template-columns: minmax(0, 0.85fr) minmax(0, 1.15fr);
    gap: clamp(28px, 4vw, 56px);
  }

  .page-about .about-eco {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    gap: clamp(28px, 4vw, 52px);
  }

  .page-about .about-steps {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 18px;
  }

  .page-about .about-step {
    border-left: 0;
    border-top: 1px solid var(--hair);
    padding: 20px 12px 0 0;
  }

  .page-about .about-step::before {
    left: 0;
    top: -5px;
  }

  .page-about .about-track {
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 16px;
  }

  .page-about .about-stage {
    border-left: 0;
    border-top: 1px solid var(--hair);
    padding: 20px 12px 0 0;
  }

  .page-about .about-stage::before {
    left: 0;
    top: -5px;
  }

  .page-about .about-section__head--wide {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 0.8fr);
    align-items: end;
    gap: 18px 40px;
  }

  .page-about .about-section__head--wide .about-section__num {
    grid-column: 1 / -1;
  }

  .page-about .about-section__head--wide .about-section__title {
    margin: 0;
  }

  .page-about .about-section__head--wide .about-section__lede {
    padding-bottom: 4px;
  }
}

@media (min-width: 1100px) {
  .page-about .about-cover {
    grid-template-columns: minmax(0, 1.12fr) minmax(0, 0.88fr);
  }

  .page-about .about-cover__media img {
    aspect-ratio: 3 / 2;
  }
}

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

  .page-about .about-index__link:hover,
  .page-about .about-index__link:focus-visible {
    transform: none;
  }
}