.page-about {
  --pa-line: 2px;
  --pa-ink-soft: rgba(245, 247, 250, .78);
  --pa-ink-faint: rgba(168, 255, 242, .72);
  --pa-frame: rgba(33, 240, 214, .28);
  background: var(--deep);
  color: var(--white);
  font-family: var(--font-sans);
  line-height: 1.75;
  overflow-wrap: break-word;
}

.page-about img {
  max-width: 100%;
  height: auto;
}

.page-about h1,
.page-about h2,
.page-about h3,
.page-about h4 {
  margin: 0;
  font-family: var(--font-sans);
  font-weight: 800;
  line-height: 1.14;
  letter-spacing: -0.02em;
  text-wrap: balance;
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding: 26px 0 40px;
  background: var(--deep);
  border-bottom: var(--pa-line) solid rgba(33, 240, 214, .22);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  top: -46%;
  right: -12%;
  width: 78%;
  height: 172%;
  background: linear-gradient(120deg, rgba(255, 77, 28, .34), rgba(255, 138, 61, .14) 45%, rgba(255, 138, 61, 0) 72%);
  transform: rotate(-14deg);
  pointer-events: none;
}

.page-about .about-hero__shell {
  position: relative;
  z-index: 1;
}

.page-about .about-crumbs {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
}

.page-about .about-crumbs ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-crumbs li {
  display: flex;
  align-items: center;
  gap: 8px;
}

.page-about .about-crumbs li + li::before {
  content: "/";
  color: var(--steel);
}

.page-about .about-crumbs a {
  color: var(--pa-ink-faint);
  text-decoration: none;
}

.page-about .about-crumbs a:hover {
  color: var(--cyan);
}

.page-about .about-crumbs__now {
  color: var(--flame);
  font-weight: 700;
}

.page-about .about-hero__eyebrow {
  margin: 30px 0 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--cyan);
}

.page-about .about-hero__title {
  font-size: clamp(36px, 8.6vw, 84px);
  font-weight: 900;
  max-width: 16ch;
  color: var(--white);
}

.page-about .about-hero__lede {
  margin: 22px 0 0;
  max-width: 36em;
  font-size: 17px;
  color: var(--pa-ink-soft);
}

.page-about .about-hero__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--pa-line);
  margin: 34px 0 0;
  padding: var(--pa-line);
  background: rgba(33, 240, 214, .32);
  border: var(--pa-line) solid rgba(33, 240, 214, .32);
}

.page-about .about-stat {
  padding: 14px 16px;
  background: var(--deep);
}

.page-about .about-stat__value {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(30px, 6.4vw, 44px);
  font-weight: 700;
  line-height: 1;
  color: var(--flame);
}

.page-about .about-stat__label {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  line-height: 1.5;
  color: var(--ice);
}

.page-about .about-hero__media {
  position: relative;
  z-index: 1;
  margin: 34px auto 0;
}

.page-about .about-hero__media img {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  border: var(--pa-line) solid rgba(33, 240, 214, .4);
}

/* ---------- 历程主体 ---------- */

.page-about .journey {
  padding: 56px 0 12px;
  background: var(--deep);
}

.page-about .journey__head {
  padding-bottom: 30px;
  border-bottom: var(--pa-line) solid rgba(168, 255, 242, .2);
}

.page-about .journey__head .eyebrow {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--cyan);
}

.page-about .journey__title {
  font-size: clamp(26px, 5.4vw, 48px);
  max-width: 20ch;
}

.page-about .journey__layout {
  padding-top: 44px;
}

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

.page-about .phase {
  position: relative;
  padding: 0 0 52px 44px;
  scroll-margin-top: 120px;
}

.page-about .phase::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 20px;
  bottom: -14px;
  width: var(--pa-line);
  background: linear-gradient(180deg, var(--cyan), rgba(33, 240, 214, .18));
}

.page-about .phase:last-child {
  padding-bottom: 10px;
}

.page-about .phase:last-child::before {
  content: none;
}

.page-about .phase__dot {
  position: absolute;
  left: 0;
  top: 8px;
  width: 16px;
  height: 16px;
  background: var(--cyan);
  box-shadow: 4px 4px 0 rgba(255, 77, 28, .6);
}

.page-about .phase__kicker {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 14px;
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--ice);
}

.page-about .phase__kicker .num {
  font-size: clamp(30px, 7vw, 46px);
  font-weight: 700;
  line-height: .9;
  color: var(--flame);
  font-variant-numeric: tabular-nums;
}

.page-about .phase__badge {
  padding: 4px 10px;
  border: 1px solid rgba(33, 240, 214, .5);
  background: rgba(33, 240, 214, .08);
  color: var(--cyan);
  white-space: nowrap;
  transition: opacity var(--dur) ease, transform var(--dur) ease;
}

@media (hover: hover) and (pointer: fine) {
  .page-about .phase__badge {
    opacity: .3;
    transform: translateY(-3px);
  }

  .page-about .phase:hover .phase__badge,
  .page-about .phase:focus-within .phase__badge {
    opacity: 1;
    transform: none;
  }
}

.page-about .phase__title {
  margin: 0 0 18px;
  font-size: clamp(23px, 4.6vw, 40px);
  max-width: 22ch;
  color: var(--white);
}

.page-about .phase__text {
  margin: 0 0 16px;
  max-width: 36em;
  font-size: 16px;
  color: var(--pa-ink-soft);
}

.page-about .phase__text:last-of-type {
  margin-bottom: 0;
}

.page-about .phase__conclusion {
  margin: 24px 0 0;
  padding: 6px 0 6px 18px;
  max-width: 34em;
  border-left: 4px solid var(--flame);
  font-family: var(--font-serif);
  font-size: 19px;
  line-height: 1.6;
  color: var(--white);
}

/* 数字条目 */

.page-about .phase__facts {
  display: grid;
  gap: 10px;
  margin: 24px 0 0;
  padding: 0;
  max-width: 34em;
  list-style: none;
}

.page-about .phase__facts li {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding: 12px 16px;
  background: var(--indigo);
  border: var(--pa-line) solid rgba(33, 240, 214, .28);
  border-left: 6px solid var(--amber);
}

.page-about .fact__num {
  min-width: 2ch;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 24px;
  font-weight: 700;
  line-height: 1;
  color: var(--cyan);
}

.page-about .fact__text {
  font-size: 15px;
  line-height: 1.6;
  color: var(--pa-ink-soft);
}

/* 配图 */

.page-about .about-figure {
  margin: 28px 0 0;
  max-width: 640px;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  object-fit: cover;
  border: var(--pa-line) solid rgba(33, 240, 214, .38);
}

.page-about .about-figure--tall img {
  aspect-ratio: 10 / 7;
}

.page-about .about-figure figcaption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--steel);
}

/* 阶梯折线图 */

.page-about .ladder {
  margin: 28px 0 0;
  max-width: 640px;
  padding: 22px 16px 14px;
  background: rgba(22, 48, 94, .62);
  border: var(--pa-line) solid rgba(33, 240, 214, .28);
}

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

.page-about .ladder__base {
  stroke: rgba(168, 255, 242, .42);
  stroke-width: 2;
}

.page-about .ladder__bar {
  fill: var(--indigo);
  stroke: var(--ice);
  stroke-width: 2;
}

.page-about .ladder__bar--now {
  fill: var(--lava);
  stroke: var(--flame);
}

.page-about .ladder__line {
  stroke: var(--cyan);
  stroke-width: 3;
}

.page-about .ladder__node {
  fill: var(--deep);
  stroke: var(--cyan);
  stroke-width: 3;
}

.page-about .ladder__label {
  fill: var(--ice);
  font-family: var(--font-mono);
  font-size: 22px;
  letter-spacing: .04em;
}

.page-about .ladder__label--now {
  fill: var(--flame);
  font-weight: 700;
}

.page-about .ladder figcaption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--steel);
}

/* 内容栏目 */

.page-about .channels {
  display: grid;
  gap: 12px;
  margin: 24px 0 0;
  max-width: 46em;
}

.page-about .channel {
  padding: 16px 15px;
  background: rgba(22, 48, 94, .72);
  border: var(--pa-line) solid rgba(168, 255, 242, .22);
  box-shadow: 4px 4px 0 rgba(17, 19, 24, .55);
}

.page-about .channel__tag {
  display: inline-block;
  margin-bottom: 10px;
  padding: 3px 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--ink);
  background: var(--flame);
}

.page-about .channel--cyan .channel__tag {
  background: var(--cyan);
}

.page-about .channel--amber .channel__tag {
  background: var(--amber);
}

.page-about .channel p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--pa-ink-soft);
}

/* 台阶清单 */

.page-about .stage-list {
  display: grid;
  gap: var(--pa-line);
  margin: 24px 0 0;
  padding: 0;
  max-width: 40em;
  list-style: none;
}

.page-about .stage-list li {
  display: grid;
  gap: 4px;
  padding: 16px 18px;
  background: rgba(22, 48, 94, .7);
  border: var(--pa-line) solid rgba(168, 255, 242, .22);
  border-left: 6px solid var(--flame);
  transition: transform var(--dur) ease, border-color var(--dur) ease;
}

.page-about .stage-list li:hover {
  transform: translate(-3px, -3px);
  border-color: rgba(33, 240, 214, .6);
}

.page-about .stage-list__n {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--cyan);
}

.page-about .stage-list h4 {
  font-size: 19px;
  font-weight: 800;
}

.page-about .stage-list p {
  margin: 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--pa-ink-soft);
}

/* 下一步清单 */

.page-about .next-list {
  display: grid;
  gap: 16px;
  margin: 24px 0 0;
  padding: 0;
  max-width: 38em;
  list-style: none;
}

.page-about .next-list li {
  display: flex;
  gap: 14px;
  align-items: flex-start;
  padding-bottom: 16px;
  border-bottom: var(--pa-line) dashed rgba(168, 255, 242, .24);
}

.page-about .next-list li:last-child {
  padding-bottom: 0;
  border-bottom: 0;
}

.page-about .next-list__n {
  flex: none;
  padding-top: 3px;
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 700;
  line-height: 1;
  color: var(--amber);
}

.page-about .next-list p {
  margin: 0;
  font-size: 16px;
  color: var(--pa-ink-soft);
}

/* 章节目录 */

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

.page-about .toc__list a[aria-current="true"] {
  color: var(--white);
  background: rgba(33, 240, 214, .12);
  border-left-color: var(--cyan);
}

/* 结尾入口 */

.page-about .about-cta {
  margin-top: 32px;
  padding: 48px 0 56px;
  background: var(--ink);
  border-top: 6px solid var(--flame);
}

.page-about .about-cta__title {
  margin: 0 0 14px;
  max-width: 20ch;
  font-size: clamp(24px, 4.6vw, 40px);
}

.page-about .about-cta__text {
  margin: 0 0 26px;
  max-width: 34em;
  font-size: 16px;
  color: var(--pa-ink-soft);
}

.page-about .about-cta__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 窄屏修正 ---------- */

@media (max-width: 479px) {
  .page-about .phase {
    padding-left: 30px;
  }

  .page-about .phase::before {
    left: 5px;
  }

  .page-about .phase__dot {
    width: 12px;
    height: 12px;
    top: 10px;
  }

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

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

/* ---------- 中屏 ---------- */

@media (min-width: 640px) {
  .page-about .about-hero {
    padding: 34px 0 48px;
  }

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

  .page-about .about-cta {
    padding: 60px 0 68px;
  }
}

/* ---------- 桌面 ---------- */

@media (min-width: 900px) {
  .page-about .journey {
    padding: 84px 0 20px;
  }

  .page-about .journey__layout {
    padding-top: 52px;
  }

  .page-about .phase {
    padding-left: 58px;
    padding-bottom: 62px;
  }

  .page-about .phase::before {
    left: 9px;
  }

  .page-about .phase__dot {
    left: 2px;
    width: 16px;
    height: 16px;
  }

  .page-about .phase__text {
    font-size: 17.5px;
  }

  .page-about .about-hero__lede {
    font-size: 19px;
  }

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

@media (min-width: 1080px) {
  .page-about .journey__layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 196px;
    gap: 56px;
    align-items: start;
  }

  .page-about .about-toc {
    display: block;
    position: sticky;
    top: 108px;
    padding-left: 20px;
    border-left: var(--pa-line) solid rgba(33, 240, 214, .3);
  }

  .page-about .toc__title {
    margin: 0 0 12px;
    font-family: var(--font-mono);
    font-size: 12px;
    letter-spacing: .16em;
    color: var(--steel);
  }

  .page-about .toc__list {
    display: grid;
    gap: 2px;
    margin: 0;
    padding: 0;
    list-style: none;
  }

  .page-about .toc__list a {
    display: block;
    padding: 7px 10px;
    font-size: 13px;
    line-height: 1.5;
    color: var(--pa-ink-faint);
    text-decoration: none;
    border-left: 2px solid transparent;
    transition: color var(--dur) ease, background-color var(--dur) ease, border-color var(--dur) ease;
  }

  .page-about .toc__list a:hover {
    color: var(--white);
    background: rgba(33, 240, 214, .12);
    border-left-color: var(--cyan);
  }

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