.page-about {
  --about-rail: 220px;
  --about-offset: 44px;
  background: var(--ink);
  color: var(--smoke);
}

.page-about .about-masthead {
  background:
    radial-gradient(120% 90% at 84% 6%, rgba(43, 179, 163, 0.12), transparent 62%),
    linear-gradient(180deg, var(--graphite) 0%, var(--ink) 72%);
  border-bottom: 1px solid var(--line);
  padding-block: clamp(24px, 4vw, 48px) clamp(38px, 6vw, 88px);
}

.page-about .about-masthead__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(26px, 5vw, 56px);
  align-items: center;
  margin-top: clamp(22px, 3.6vw, 44px);
}

.page-about .about-masthead__eyebrow {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--teal);
  margin: 0 0 16px;
}

.page-about .about-masthead__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(2rem, 5.6vw, 3.8rem);
  line-height: 1.12;
  letter-spacing: -0.02em;
  color: var(--paper);
  margin: 0 0 clamp(16px, 2.4vw, 26px);
  max-width: 17ch;
}

.page-about .about-masthead__lede {
  font-size: clamp(15px, 1.1vw, 17px);
  line-height: 1.9;
  color: var(--smoke);
  max-width: 48ch;
  margin: 0 0 clamp(20px, 3vw, 30px);
}

.page-about .about-masthead__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 10px clamp(16px, 3vw, 34px);
  margin: 0 0 clamp(22px, 3.4vw, 34px);
  padding: 18px 0 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.page-about .about-masthead__facts li {
  display: flex;
  align-items: baseline;
  gap: 8px;
  font-size: 13px;
  color: var(--mist);
}

.page-about .about-masthead__num {
  font-family: var(--font-mono);
  font-size: 22px;
  letter-spacing: 0.02em;
  color: var(--teal);
}

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

.page-about .about-masthead__figure {
  margin: 0;
  border: 1px solid var(--line-strong);
  background: var(--graphite);
  overflow: hidden;
  box-shadow: var(--shadow-deep);
}

.page-about .about-masthead__figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  aspect-ratio: 14 / 9;
  object-fit: cover;
}

.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 4vw, 56px);
  padding-block: clamp(34px, 5.5vw, 78px);
}

.page-about .about-rail {
  align-self: start;
}

.page-about .about-rail__label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--bronze);
  margin: 0 0 12px;
}

.page-about .about-rail__list {
  display: flex;
  gap: 8px;
  margin: 0;
  padding: 0 0 10px;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-rail__list a {
  display: block;
  white-space: nowrap;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.05em;
  color: var(--mist);
  text-decoration: none;
  padding: 8px 12px;
  border: 1px solid var(--line);
  transition: color 0.25s var(--ease), border-color 0.25s var(--ease), background 0.25s var(--ease);
}

.page-about .about-rail__list a:hover,
.page-about .about-rail__list a:focus-visible {
  color: var(--paper);
  border-color: var(--teal);
  background: rgba(43, 179, 163, 0.08);
}

.page-about .about-rail__back {
  display: inline-block;
  margin-top: 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--bronze);
  text-decoration: none;
  border: 1px solid var(--line-strong);
  padding: 9px 14px;
  transition: color 0.25s var(--ease), border-color 0.25s var(--ease);
}

.page-about .about-rail__back:hover,
.page-about .about-rail__back:focus-visible {
  color: var(--paper);
  border-color: var(--teal);
}

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

.page-about .about-section {
  padding-block: clamp(28px, 4.4vw, 52px);
  border-top: 1px solid var(--line);
  scroll-margin-top: 96px;
}

.page-about .about-section:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .about-section__index {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--bronze);
  margin: 0 0 14px;
}

.page-about .about-section__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.45rem, 3.2vw, 2.3rem);
  line-height: 1.28;
  letter-spacing: -0.01em;
  color: var(--paper);
  margin: 0 0 clamp(16px, 2.4vw, 24px);
  max-width: 21ch;
}

.page-about .about-section__lede,
.page-about .about-section__body p,
.page-about .about-split__main p {
  font-size: 15.5px;
  line-height: 1.9;
  color: var(--smoke);
  max-width: 62ch;
  margin: 0 0 15px;
}

.page-about .about-section__body p:last-child,
.page-about .about-split__main p:last-child {
  margin-bottom: 0;
}

/* 时间线 */
.page-about .about-timeline {
  position: relative;
  list-style: none;
  margin: clamp(16px, 2.4vw, 26px) 0 0;
  padding: 0 0 0 26px;
}

.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 12px;
  bottom: 12px;
  width: 1px;
  background: linear-gradient(180deg, var(--teal), var(--line) 46%, var(--line));
}

.page-about .about-timeline__item {
  position: relative;
  margin-bottom: 12px;
}

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 19px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--ink);
  border: 1px solid var(--teal);
}

.page-about .about-timeline__item.is-current::before {
  background: var(--coral);
  border-color: var(--coral);
  box-shadow: 0 0 0 4px rgba(255, 111, 94, 0.16);
}

.page-about .about-timeline__card {
  background: var(--graphite);
  border: 1px solid var(--line);
  transition: border-color 0.3s var(--ease);
}

.page-about .about-timeline__card:hover {
  border-color: var(--line-strong);
}

.page-about .about-timeline__card[open] {
  border-color: var(--line-strong);
}

.page-about .about-timeline__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 4px 14px;
  padding: 15px 18px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-timeline__head:focus-visible {
  outline: 2px solid var(--teal);
  outline-offset: -2px;
}

.page-about .about-timeline__head::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--teal);
  line-height: 1;
}

.page-about .about-timeline__card[open] .about-timeline__head::after {
  content: "−";
}

.page-about .about-timeline__phase {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--teal);
}

.page-about .about-timeline__item.is-current .about-timeline__phase {
  color: var(--coral);
}

.page-about .about-timeline__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  line-height: 1.5;
  color: var(--paper);
}

.page-about .about-timeline__text {
  margin: 0;
  padding: 0 18px 18px;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--smoke);
  max-width: 58ch;
}

/* 图文分栏 */
.page-about .about-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3.4vw, 38px);
  margin-top: clamp(16px, 2.4vw, 26px);
}

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

.page-about .about-split__panel {
  background: var(--graphite);
  border-top: 1px solid var(--line-strong);
  padding: clamp(16px, 2.4vw, 24px);
}

.page-about .about-stat {
  padding: 13px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .about-stat:first-child {
  padding-top: 0;
}

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

.page-about .about-stat__label {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--mist);
  margin-bottom: 5px;
}

.page-about .about-stat__value {
  display: block;
  font-size: 15px;
  line-height: 1.6;
  color: var(--paper);
}

.page-about .about-stat__note {
  display: block;
  margin-top: 6px;
  font-size: 12px;
  line-height: 1.7;
  color: var(--mist);
  opacity: 0.75;
  transition: opacity 0.3s var(--ease), color 0.3s var(--ease);
}

.page-about .about-stat:hover .about-stat__note,
.page-about .about-stat:focus-within .about-stat__note {
  opacity: 1;
  color: var(--teal);
}

/* 四道工序 */
.page-about .about-steps {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .about-steps__item {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  column-gap: 14px;
  padding: 16px 0;
  border-bottom: 1px solid var(--line-soft);
}

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

.page-about .about-steps__num {
  grid-column: 1;
  grid-row: 1 / span 2;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--teal);
  padding-top: 4px;
}

.page-about .about-steps__title {
  grid-column: 2;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  line-height: 1.4;
  color: var(--paper);
  margin: 0 0 6px;
}

.page-about .about-steps__text {
  grid-column: 2;
  margin: 0;
  font-size: 14.5px;
  line-height: 1.82;
  color: var(--smoke);
}

/* 图片 */
.page-about .about-figure {
  margin: clamp(20px, 3vw, 32px) 0 0;
  border: 1px solid var(--line);
  background: var(--graphite);
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .about-figure__caption {
  padding: 10px 14px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.05em;
  line-height: 1.7;
  color: var(--mist);
  border-top: 1px solid var(--line);
}

/* 合作数据 */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  margin-top: clamp(16px, 2.4vw, 26px);
}

.page-about .about-stats__item {
  background: var(--graphite);
  padding: clamp(16px, 2.4vw, 24px);
  transition: background 0.3s var(--ease);
}

.page-about .about-stats__item:hover {
  background: #222E35;
}

.page-about .about-stats__num {
  display: block;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.6rem, 3.2vw, 2.3rem);
  line-height: 1;
  letter-spacing: -0.01em;
  color: var(--paper);
  margin-bottom: 10px;
}

.page-about .about-stats__item:last-child .about-stats__num {
  color: var(--bronze);
}

.page-about .about-stats__label {
  display: block;
  font-size: 13px;
  line-height: 1.65;
  color: var(--mist);
}

/* 四条原则 */
.page-about .about-principles {
  list-style: none;
  margin: clamp(16px, 2.4vw, 26px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-principles__item {
  background: var(--graphite);
  padding: clamp(18px, 2.6vw, 26px);
}

.page-about .about-principles__num {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--bronze);
  margin-bottom: 10px;
}

.page-about .about-principles__item h3 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 19px;
  line-height: 1.4;
  color: var(--paper);
  margin: 0 0 8px;
}

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

/* 下一步 */
.page-about .about-cta {
  margin-top: clamp(26px, 4vw, 46px);
  padding: clamp(24px, 4vw, 44px);
  border: 1px solid var(--line-strong);
  background:
    linear-gradient(150deg, rgba(15, 94, 90, 0.34), rgba(28, 37, 43, 0.9) 58%),
    var(--graphite);
}

.page-about .about-cta__eyebrow {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--coral);
  margin: 0 0 12px;
}

.page-about .about-cta__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.35rem, 2.9vw, 2rem);
  line-height: 1.3;
  letter-spacing: -0.01em;
  color: var(--paper);
  margin: 0 0 12px;
  max-width: 22ch;
}

.page-about .about-cta__text {
  margin: 0 0 clamp(18px, 2.6vw, 26px);
  font-size: 15px;
  line-height: 1.85;
  color: var(--smoke);
  max-width: 52ch;
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: clamp(18px, 2.6vw, 26px);
}

.page-about .about-cta__links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 24px;
  margin: 0;
  padding: 16px 0 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.page-about .about-cta__links a {
  font-size: 13.5px;
  color: var(--smoke);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.25s var(--ease), border-color 0.25s var(--ease);
}

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

/* 固定回目录 */
.page-about .about-back {
  position: fixed;
  right: 16px;
  bottom: 16px;
  z-index: 40;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  padding: 10px 15px;
  color: var(--ink);
  background: var(--coral);
  border: 1px solid var(--coral);
  text-decoration: none;
  box-shadow: var(--shadow-deep);
  transition: background 0.25s var(--ease), color 0.25s var(--ease);
}

.page-about .about-back:hover,
.page-about .about-back:focus-visible {
  background: var(--ink);
  color: var(--coral);
}

@media (min-width: 640px) {
  .page-about .about-principles {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .page-about .about-masthead__grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  }

  .page-about .about-timeline {
    padding-left: 34px;
  }

  .page-about .about-timeline::before {
    left: 7px;
  }

  .page-about .about-timeline__item::before {
    left: -34px;
  }

  .page-about .about-timeline__item:nth-child(even) {
    margin-left: var(--about-offset);
  }

  .page-about .about-timeline__item:nth-child(even)::before {
    left: calc(-34px - var(--about-offset));
  }

  .page-about .about-split {
    grid-template-columns: minmax(0, 1.4fr) minmax(0, 0.6fr);
    align-items: start;
  }

  .page-about .about-split--reverse {
    grid-template-columns: minmax(0, 0.6fr) minmax(0, 1.4fr);
  }

  .page-about .about-split--reverse .about-split__panel {
    order: -1;
  }

  .page-about .about-figure img {
    max-height: 460px;
  }
}

@media (min-width: 1024px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
  }

  .page-about .about-rail {
    position: sticky;
    top: 104px;
    border-left: 1px solid var(--line);
    padding-left: 20px;
  }

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

  .page-about .about-rail__list li + li {
    margin-top: 2px;
  }

  .page-about .about-rail__list a {
    white-space: normal;
    border: 0;
    border-left: 2px solid transparent;
    padding: 7px 0 7px 12px;
    transition: color 0.25s var(--ease), border-color 0.25s var(--ease);
  }

  .page-about .about-rail__list a:hover,
  .page-about .about-rail__list a:focus-visible {
    background: none;
    border-left-color: var(--teal);
  }

  .page-about .about-back {
    right: 28px;
    bottom: 28px;
  }
}

@media (min-width: 1200px) {
  .page-about {
    --about-rail: 244px;
    --about-offset: 66px;
  }

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

  .page-about .about-stats__item:last-child {
    grid-column: span 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail__list a,
  .page-about .about-rail__back,
  .page-about .about-timeline__card,
  .page-about .about-stat__note,
  .page-about .about-stats__item,
  .page-about .about-cta__links a,
  .page-about .about-back {
    transition: none;
  }
}