.page-about {
  --about-sec: 84px;
  --about-sticky-top: calc(var(--header-h) + 28px);
  background:
    radial-gradient(90% 60% at 85% 8%, rgba(56, 242, 208, 0.07) 0%, transparent 60%),
    linear-gradient(180deg, var(--ink) 0%, var(--green-900) 45%, var(--ink) 100%);
  color: var(--text);
  font-family: var(--font-head);
  overflow-x: clip;
}

.page-about .about-link {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(56, 242, 208, 0.45);
  padding-bottom: 1px;
  transition: color 160ms var(--ease), border-color 160ms var(--ease);
}

.page-about .about-link:hover {
  color: var(--cyan-soft);
  border-bottom-color: var(--cyan-soft);
}

.page-about a:focus-visible,
.page-about summary:focus-visible {
  outline: 2px solid var(--orange);
  outline-offset: 3px;
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  position: relative;
  padding: calc(var(--header-h) + 56px) 0 64px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, var(--line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--line) 1px, transparent 1px);
  background-size: 96px 96px;
  opacity: 0.4;
  pointer-events: none;
}

.page-about .about-hero .shell {
  position: relative;
}

.page-about .about-hero__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 36px;
  margin-top: 34px;
}

.page-about .about-hero h1 {
  margin: 16px 0 0;
  font-size: clamp(2.1rem, 7.4vw, 4.4rem);
  line-height: 1.02;
  font-weight: 900;
  letter-spacing: -0.02em;
  color: var(--text);
  max-width: 15ch;
}

.page-about .about-hero__lede {
  margin: 22px 0 0;
  max-width: 46ch;
  font-size: 1rem;
  line-height: 1.75;
  color: var(--text-dim);
  border-left: 2px solid var(--cyan);
  padding-left: 16px;
}

.page-about .about-index {
  align-self: start;
  border: 1px solid var(--line);
  background: linear-gradient(160deg, rgba(18, 54, 44, 0.92) 0%, rgba(10, 31, 26, 0.92) 100%);
  padding: 22px 20px 18px;
}

.page-about .about-index__list {
  margin: 16px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-index__row {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
}

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

.page-about .about-index__num {
  font-family: var(--font-mono);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--cyan);
  letter-spacing: -0.01em;
  line-height: 1.1;
}

.page-about .about-index__key {
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  color: var(--text-dim);
}

.page-about .about-index__note {
  margin: 14px 0 0;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  color: var(--amber);
  text-transform: uppercase;
}

/* ---------- 起点 ---------- */

.page-about .about-origin {
  padding: var(--about-sec) 0;
}

.page-about .about-origin__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 44px;
}

.page-about .about-origin h2 {
  margin: 14px 0 0;
  font-size: clamp(1.55rem, 4.6vw, 2.6rem);
  line-height: 1.14;
  font-weight: 800;
  letter-spacing: -0.015em;
  color: var(--text);
  max-width: 18ch;
}

.page-about .about-origin__text p {
  margin: 18px 0 0;
  max-width: 52ch;
  font-size: 0.98rem;
  line-height: 1.8;
  color: var(--text-dim);
}

.page-about .about-origin__list {
  margin: 34px 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.page-about .about-origin__item {
  display: grid;
  grid-template-columns: 5.2rem 1fr;
  gap: 6px 16px;
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .about-origin__num {
  grid-row: span 2;
  font-family: var(--font-mono);
  font-size: 1.42rem;
  font-weight: 700;
  color: var(--cyan);
  border-bottom: 1px solid rgba(56, 242, 208, 0.5);
  padding-bottom: 4px;
  align-self: start;
}

.page-about .about-origin__label {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text);
}

.page-about .about-origin__desc {
  font-size: 0.82rem;
  line-height: 1.65;
  color: var(--text-dim);
}

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

/* ---------- 通用图片框 ---------- */

.page-about .figure {
  margin: 0;
  border: 1px solid var(--line);
}

.page-about .figure__img {
  background: linear-gradient(150deg, var(--green-700) 0%, var(--ink) 100%);
}

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

.page-about .figure__caption {
  padding: 12px 14px;
  font-size: 0.78rem;
  line-height: 1.6;
  color: var(--text-dim);
  border-top: 1px solid var(--line);
}

/* ---------- 分工与字段 ---------- */

.page-about .about-method {
  position: relative;
  padding: calc(var(--about-sec) + 20px) 0;
  background: linear-gradient(180deg, rgba(10, 31, 26, 0.96) 0%, rgba(5, 11, 10, 0.96) 100%);
  clip-path: polygon(0 2.2%, 100% 0, 100% 97.8%, 0 100%);
}

.page-about .about-method__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 44px;
}

.page-about .about-method h2 {
  margin: 14px 0 0;
  font-size: clamp(1.5rem, 4.4vw, 2.4rem);
  line-height: 1.16;
  font-weight: 800;
  letter-spacing: -0.015em;
  color: var(--text);
  max-width: 20ch;
}

.page-about .about-method__lede {
  margin: 16px 0 0;
  max-width: 50ch;
  font-size: 0.95rem;
  line-height: 1.78;
  color: var(--text-dim);
}

.page-about .about-method__cards {
  margin: 32px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-role {
  background: var(--green-700);
  padding: 22px 20px;
  transition: box-shadow 180ms var(--ease), transform 180ms var(--ease);
}

.page-about .about-role:hover {
  transform: translateY(-2px);
  box-shadow: inset 0 0 0 1px var(--cyan);
}

.page-about .about-role__count {
  font-family: var(--font-mono);
  font-size: 2.1rem;
  font-weight: 700;
  line-height: 1;
  color: var(--cyan);
  border-bottom: 1px solid rgba(56, 242, 208, 0.5);
  display: inline-block;
  padding-bottom: 4px;
}

.page-about .about-role__title {
  margin: 12px 0 0;
  font-size: 1.06rem;
  font-weight: 800;
  color: var(--text);
}

.page-about .about-role__body {
  margin: 10px 0 0;
  font-size: 0.88rem;
  line-height: 1.72;
  color: var(--text-dim);
}

.page-about .about-role__tag {
  margin: 14px 0 0;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  color: var(--cyan-soft);
  text-transform: uppercase;
}

.page-about .about-method__figure {
  margin-top: 32px;
}

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

.page-about .about-fields__intro {
  margin: 12px 0 18px;
  font-size: 0.84rem;
  line-height: 1.7;
  color: var(--text-dim);
}

.page-about .about-fields__stack {
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

/* ---------- 折叠组件 ---------- */

.page-about .about-fold {
  background: var(--green-900);
}

.page-about .about-fold__summary {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 16px;
  cursor: pointer;
  list-style: none;
  transition: background 160ms var(--ease);
}

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

.page-about .about-fold__summary:hover {
  background: rgba(56, 242, 208, 0.06);
}

.page-about .about-fold__title {
  flex: 1 1 auto;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: 0.01em;
}

.page-about .about-fold__no {
  font-family: var(--font-mono);
  font-size: 0.86rem;
  font-weight: 700;
  color: var(--cyan);
}

.page-about .about-fold__mark {
  position: relative;
  flex: 0 0 auto;
  width: 12px;
  height: 12px;
  border: 1px solid var(--cyan);
}

.page-about .about-fold__mark::before,
.page-about .about-fold__mark::after {
  content: "";
  position: absolute;
  background: var(--cyan);
}

.page-about .about-fold__mark::before {
  left: 2px;
  right: 2px;
  top: 50%;
  height: 1px;
  transform: translateY(-50%);
}

.page-about .about-fold__mark::after {
  top: 2px;
  bottom: 2px;
  left: 50%;
  width: 1px;
  transform: translateX(-50%);
  transition: opacity 160ms var(--ease);
}

.page-about .about-fold[open] .about-fold__mark::after {
  opacity: 0;
}

.page-about .about-fold__body {
  margin: 0;
  padding: 0 16px 16px;
  font-size: 0.85rem;
  line-height: 1.75;
  color: var(--text-dim);
  border-top: 1px solid var(--line);
  padding-top: 12px;
}

/* ---------- 校对 ---------- */

.page-about .about-review {
  padding: var(--about-sec) 0;
}

.page-about .about-review h2 {
  margin: 14px 0 0;
  font-size: clamp(1.5rem, 4.4vw, 2.4rem);
  line-height: 1.16;
  font-weight: 800;
  letter-spacing: -0.015em;
  color: var(--text);
  max-width: 20ch;
}

.page-about .about-review__lede {
  margin: 16px 0 0;
  max-width: 52ch;
  font-size: 0.95rem;
  line-height: 1.78;
  color: var(--text-dim);
}

.page-about .about-review__steps {
  margin: 36px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-review__step {
  display: block;
}

.page-about .about-fold--step {
  background: var(--green-700);
}

.page-about .about-fold--step .about-fold__summary {
  padding: 18px 18px;
}

.page-about .about-fold--step .about-fold__title {
  font-size: 0.98rem;
}

.page-about .about-review__callout {
  margin-top: 32px;
}

.page-about .about-review__meta {
  margin: 22px 0 0;
  max-width: 56ch;
  font-size: 0.86rem;
  line-height: 1.75;
  color: var(--text-dim);
}

/* ---------- 版本演进 ---------- */

.page-about .about-versions {
  padding: 0 0 var(--about-sec);
}

.page-about .about-versions__band {
  position: relative;
  margin: 0 0 56px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: var(--indigo);
  overflow: hidden;
}

.page-about .about-versions__band img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: clamp(110px, 17vw, 210px);
  object-fit: cover;
  opacity: 0.72;
  mix-blend-mode: screen;
}

.page-about .about-versions__head {
  max-width: 62ch;
}

.page-about .about-versions h2 {
  margin: 14px 0 0;
  font-size: clamp(1.5rem, 4.4vw, 2.4rem);
  line-height: 1.16;
  font-weight: 800;
  letter-spacing: -0.015em;
  color: var(--text);
}

.page-about .about-versions__lede {
  margin: 16px 0 0;
  font-size: 0.95rem;
  line-height: 1.78;
  color: var(--text-dim);
}

.page-about .about-scale {
  display: flex;
  margin: 36px 0 0;
  padding: 0;
  list-style: none;
  overflow-x: auto;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  scrollbar-width: thin;
}

.page-about .about-scale__item {
  flex: 1 0 auto;
  min-width: 116px;
}

.page-about .about-scale__link {
  position: relative;
  display: block;
  padding: 20px 18px 16px;
  border-right: 1px solid var(--line);
  text-decoration: none;
  color: var(--text-dim);
  transition: background 160ms var(--ease), color 160ms var(--ease);
}

.page-about .about-scale__item:first-child .about-scale__link {
  border-left: 1px solid var(--line);
}

.page-about .about-scale__link:hover {
  background: rgba(56, 242, 208, 0.07);
  color: var(--text);
}

.page-about .about-scale__dot {
  display: block;
  width: 9px;
  height: 9px;
  margin-bottom: 12px;
  background: var(--line);
  border: 1px solid var(--cyan);
  transition: transform 160ms var(--ease), background 160ms var(--ease);
}

.page-about .about-scale__link:hover .about-scale__dot {
  transform: scale(1.4);
  background: var(--cyan);
}

.page-about .about-scale__ver {
  display: block;
  font-family: var(--font-mono);
  font-size: 1.16rem;
  font-weight: 700;
  color: var(--text);
}

.page-about .about-scale__year {
  display: block;
  margin-top: 4px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  color: var(--text-dim);
}

.page-about .about-scale__link--current {
  background: rgba(255, 106, 43, 0.1);
}

.page-about .about-scale__link--current .about-scale__dot {
  background: var(--orange);
  border-color: var(--orange);
}

.page-about .about-scale__link--current .about-scale__ver {
  color: var(--orange);
}

.page-about .about-versions__stack {
  display: grid;
  gap: 22px;
  margin-top: 42px;
}

.page-about .about-version {
  position: relative;
  padding: 26px 22px 24px;
  background: var(--green-900);
  border: 1px solid var(--line);
  scroll-margin-top: calc(var(--header-h) + 24px);
  transition: box-shadow 180ms var(--ease), transform 180ms var(--ease);
}

.page-about .about-version::before {
  content: "";
  position: absolute;
  left: -1px;
  top: -1px;
  bottom: -1px;
  width: 4px;
  background: var(--indigo);
}

.page-about .about-version--wine::before {
  background: var(--wine);
}

.page-about .about-version:hover {
  transform: translateY(-2px);
  box-shadow: inset 0 0 0 1px var(--cyan);
}

.page-about .about-version__tag {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--cyan-soft);
}

.page-about .about-version__tag--current {
  color: var(--orange);
}

.page-about .about-version__title {
  margin: 12px 0 0;
  font-size: 1.16rem;
  font-weight: 800;
  line-height: 1.3;
  color: var(--text);
}

.page-about .about-version__body {
  margin: 12px 0 0;
  font-size: 0.9rem;
  line-height: 1.76;
  color: var(--text-dim);
  max-width: 54ch;
}

.page-about .about-version__fields {
  margin: 16px 0 0;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.1em;
  color: var(--text-dim);
}

.page-about .about-versions__foot {
  margin: 34px 0 0;
  max-width: 58ch;
  font-size: 0.86rem;
  line-height: 1.78;
  color: var(--text-dim);
  border-left: 3px solid var(--amber);
  padding-left: 16px;
}

/* ---------- 基本信息 ---------- */

.page-about .about-facts {
  padding: 0 0 var(--about-sec);
}

.page-about .about-facts__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 36px;
}

.page-about .about-facts h2 {
  margin: 14px 0 0;
  font-size: clamp(1.5rem, 4.4vw, 2.2rem);
  line-height: 1.18;
  font-weight: 800;
  letter-spacing: -0.015em;
  color: var(--text);
}

.page-about .about-facts__lede {
  margin: 16px 0 0;
  max-width: 44ch;
  font-size: 0.9rem;
  line-height: 1.78;
  color: var(--text-dim);
}

.page-about .about-facts__list {
  margin: 0;
  border-top: 1px solid var(--line);
}

.page-about .about-facts__row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 4px;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .about-facts__row dt {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--cyan-soft);
}

.page-about .about-facts__row dd {
  margin: 0;
  font-size: 0.92rem;
  line-height: 1.7;
  color: var(--text);
}

.page-about .about-next {
  margin-top: 48px;
  padding: 24px 20px;
  border: 1px solid var(--line);
  background: linear-gradient(120deg, rgba(90, 29, 46, 0.28) 0%, rgba(36, 31, 74, 0.28) 100%);
}

.page-about .about-next__label {
  margin: 0 0 16px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-dim);
}

.page-about .about-next__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-next__link {
  display: flex;
  flex-direction: column;
  gap: 5px;
  padding: 16px 16px;
  background: var(--ink);
  text-decoration: none;
  color: var(--text);
  font-size: 0.95rem;
  font-weight: 700;
  transition: background 160ms var(--ease), color 160ms var(--ease);
}

.page-about .about-next__link:hover {
  background: rgba(56, 242, 208, 0.08);
  color: var(--cyan-soft);
}

.page-about .about-next__hint {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  font-weight: 400;
  color: var(--text-dim);
}

/* ---------- 响应式 ---------- */

@media (min-width: 720px) {
  .page-about .about-origin__item {
    grid-template-columns: 6rem 1fr;
    align-items: baseline;
  }

  .page-about .about-facts__row {
    grid-template-columns: 12rem 1fr;
    gap: 24px;
    align-items: baseline;
  }

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

@media (min-width: 960px) {
  .page-about {
    --about-sec: 116px;
  }

  .page-about .about-hero {
    padding: calc(var(--header-h) + 88px) 0 96px;
  }

  .page-about .about-hero__grid {
    grid-template-columns: repeat(12, 1fr);
    gap: 48px;
    align-items: end;
    margin-top: 52px;
  }

  .page-about .about-hero__lead {
    grid-column: 1 / span 8;
  }

  .page-about .about-index {
    grid-column: 9 / span 4;
  }

  .page-about .about-origin__grid {
    grid-template-columns: repeat(12, 1fr);
    gap: 56px;
  }

  .page-about .about-origin__text {
    grid-column: 1 / span 7;
  }

  .page-about .about-origin__figure {
    grid-column: 8 / span 5;
    margin-top: 34px;
  }

  .page-about .about-method__grid {
    grid-template-columns: repeat(12, 1fr);
    gap: 48px;
  }

  .page-about .about-method__main {
    grid-column: 1 / span 7;
  }

  .page-about .about-fields {
    grid-column: 9 / span 4;
    position: sticky;
    top: var(--about-sticky-top);
  }

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

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

  .page-about .about-versions__stack {
    grid-template-columns: repeat(12, 1fr);
    gap: 30px 24px;
    margin-top: 56px;
  }

  .page-about .about-version:nth-child(odd) {
    grid-column: 1 / span 7;
  }

  .page-about .about-version:nth-child(even) {
    grid-column: 6 / span 7;
    margin-top: 40px;
  }

  .page-about .about-facts__grid {
    grid-template-columns: repeat(12, 1fr);
    gap: 56px;
  }

  .page-about .about-facts__head {
    grid-column: 1 / span 4;
  }

  .page-about .about-facts__list {
    grid-column: 5 / span 8;
  }

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

@media (min-width: 1200px) {
  .page-about .about-versions__band {
    margin-bottom: 72px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-role,
  .page-about .about-version,
  .page-about .about-scale__dot,
  .page-about .about-next__link {
    transition: none;
  }

  .page-about .about-role:hover,
  .page-about .about-version:hover {
    transform: none;
  }
}
</main>