.page-about {
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding-block: clamp(20px, 3vw, 34px) clamp(30px, 5vw, 62px);
}

.page-about .about-hero__frame {
  position: relative;
  display: grid;
  gap: clamp(26px, 4vw, 48px);
  align-items: end;
}

.page-about .about-hero__frame::before {
  content: "";
  position: absolute;
  top: -8%;
  right: -5%;
  width: min(48%, 460px);
  height: 78%;
  background: linear-gradient(150deg, var(--pitch-600), var(--eblue-600) 62%, var(--volt-500));
  clip-path: polygon(24% 0, 100% 0, 100% 72%, 0 100%);
  opacity: .11;
  pointer-events: none;
}

.page-about .about-hero__body,
.page-about .about-hero__media {
  position: relative;
  z-index: 1;
}

.page-about .about-hero__kicker {
  margin: 0;
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--pitch-600);
}

.page-about .about-hero__title {
  margin: 14px 0 0;
  font-family: var(--font-display);
  font-size: clamp(2.05rem, 5.4vw, 3.9rem);
  line-height: 1.14;
  letter-spacing: -.012em;
  color: var(--ink-900);
  max-width: 17ch;
}

.page-about .about-hero__lead {
  margin: clamp(16px, 2.2vw, 22px) 0 0;
  font-size: clamp(1rem, 1.4vw, 1.1rem);
  line-height: 1.78;
  color: var(--ink-600);
  max-width: 60ch;
}

.page-about .about-hero__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 10px clamp(18px, 3vw, 34px);
  margin: clamp(20px, 2.6vw, 28px) 0 0;
  padding: 14px 0 0;
  border-top: 1px solid var(--line);
}

.page-about .about-hero__fact {
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.page-about .about-hero__fact dt {
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .1em;
  color: var(--ink-600);
}

.page-about .about-hero__fact dd {
  margin: 0;
  font-size: .95rem;
  font-weight: 600;
  color: var(--ink-900);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(22px, 3vw, 30px);
}

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

@media (min-width: 900px) {
  .page-about .about-hero__frame {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  }
}

/* ---------- 目录 + 内容流 ---------- */
.page-about .about-archive {
  display: grid;
  gap: clamp(30px, 4vw, 52px);
  border-top: 1px solid var(--line);
  padding-block: clamp(30px, 4vw, 52px) clamp(40px, 6vw, 80px);
}

.page-about .about-rail__label {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .18em;
  color: var(--ink-600);
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 0 14px;
  border-left: 1px solid var(--line);
  display: grid;
  gap: 2px;
}

.page-about .about-rail__link {
  display: grid;
  grid-template-columns: 32px minmax(0, 1fr);
  gap: 8px;
  align-items: baseline;
  padding: 9px 8px;
  border-radius: var(--r-sm);
  text-decoration: none;
  color: var(--ink-600);
  transition: background-color 200ms var(--ease), color 200ms var(--ease), transform 200ms var(--ease);
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  background: var(--paper-100);
  color: var(--ink-900);
  transform: translateX(4px);
}

.page-about .about-rail__num {
  font-family: var(--font-mono);
  font-size: .8rem;
  font-variant-numeric: tabular-nums;
  color: var(--volt-500);
  letter-spacing: .04em;
}

.page-about .about-rail__text {
  font-size: .95rem;
  line-height: 1.4;
}

@media (min-width: 980px) {
  .page-about .about-archive {
    grid-template-columns: minmax(168px, 212px) minmax(0, 1fr);
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h) + 26px);
    align-self: start;
  }
}

/* ---------- 章节 ---------- */
.page-about .about-stage {
  padding-block: clamp(26px, 3.6vw, 44px);
  border-bottom: 1px solid var(--line-soft);
}

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

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

.page-about .about-stage__num {
  margin: 0;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .16em;
  color: var(--pitch-600);
}

.page-about .about-stage__title {
  margin: .6rem 0 .9rem;
  font-family: var(--font-display);
  font-size: clamp(1.45rem, 3vw, 2.1rem);
  line-height: 1.28;
  letter-spacing: -.008em;
  color: var(--ink-900);
  max-width: 24ch;
}

.page-about .about-flow p {
  margin: 0 0 1em;
  font-size: 1.01rem;
  line-height: 1.78;
  color: var(--ink-600);
  max-width: 66ch;
}

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

/* ---------- 版本时间轴 ---------- */
.page-about .about-version {
  list-style: none;
  margin: clamp(22px, 3vw, 32px) 0 0;
  padding: 0 0 0 clamp(20px, 3vw, 32px);
  border-left: 1px solid var(--line);
  display: grid;
  gap: clamp(18px, 2.6vw, 28px);
}

.page-about .about-version__item {
  position: relative;
}

.page-about .about-version__item::before {
  content: "";
  position: absolute;
  top: 7px;
  left: calc(-1 * clamp(20px, 3vw, 32px) - 4px);
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--pitch-600);
  box-shadow: 0 0 0 3px var(--paper-000);
}

.page-about .about-version__title {
  margin: 10px 0 6px;
  font-size: 1.06rem;
  font-weight: 700;
  line-height: 1.45;
  color: var(--ink-900);
}

.page-about .about-version__item p {
  margin: 0;
  font-size: .95rem;
  line-height: 1.75;
  color: var(--ink-600);
  max-width: 58ch;
}

.page-about .about-version__figure {
  margin: clamp(24px, 3vw, 34px) 0 0;
}

.page-about .about-field__figure {
  margin: clamp(20px, 3vw, 30px) 0;
  max-width: 520px;
}

/* ---------- 观察员折叠 ---------- */
.page-about .about-watch {
  margin-top: clamp(22px, 3vw, 30px);
}

.page-about .about-watch__question {
  font-weight: 600;
}

.page-about .about-watch__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .about-watch__list li {
  display: grid;
  gap: 4px;
  padding-left: 14px;
  border-left: 2px solid var(--eblue-100);
}

.page-about .about-watch__key {
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .12em;
  color: var(--eblue-600);
}

.page-about .about-watch__val {
  font-size: .95rem;
  line-height: 1.72;
  color: var(--ink-600);
}

/* ---------- 里程碑数据 ---------- */
.page-about .about-metrics {
  display: grid;
  gap: 2px;
  margin-top: clamp(20px, 3vw, 30px);
  background: var(--line-soft);
  border: 1px solid var(--line);
}

.page-about .about-metric {
  background: var(--paper-000);
  padding: clamp(18px, 2.4vw, 26px);
  transition: background-color 220ms var(--ease), transform 220ms var(--ease);
}

.page-about .about-metric:hover {
  background: var(--paper-100);
  transform: translateY(-2px);
}

.page-about .about-metric__value {
  margin: 0;
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 3vw, 2rem);
  line-height: 1.05;
  letter-spacing: -.02em;
  font-variant-numeric: tabular-nums;
  color: var(--ink-900);
}

.page-about .about-metric__unit {
  margin-left: 2px;
  font-size: .58em;
  color: var(--volt-500);
}

.page-about .about-metric__label {
  margin: 10px 0 6px;
  font-size: .95rem;
  font-weight: 600;
  color: var(--ink-900);
}

.page-about .about-metric__note {
  margin: 0;
  font-size: .82rem;
  line-height: 1.62;
  color: var(--ink-600);
}

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

@media (min-width: 1020px) {
  .page-about .about-metrics {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

/* ---------- 三条坚持 ---------- */
.page-about .about-pledge {
  display: grid;
  gap: clamp(14px, 2vw, 20px);
  margin-top: clamp(20px, 3vw, 28px);
}

.page-about .about-pledge__item {
  margin: 0;
  padding: clamp(18px, 2.4vw, 26px);
  background: var(--paper-100);
  border-top: 3px solid var(--pitch-600);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 18px), calc(100% - 18px) 100%, 0 100%);
}

.page-about .about-pledge__item:nth-child(2) {
  border-top-color: var(--eblue-600);
}

.page-about .about-pledge__item:nth-child(3) {
  border-top-color: var(--volt-500);
}

.page-about .about-pledge__lead {
  margin: 0 0 .55em;
  font-family: var(--font-display);
  font-size: 1.15rem;
  line-height: 1.45;
  color: var(--ink-900);
}

.page-about .about-pledge__text {
  margin: 0;
  font-size: .92rem;
  line-height: 1.74;
  color: var(--ink-600);
}

@media (min-width: 860px) {
  .page-about .about-pledge {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  margin-top: clamp(28px, 4vw, 44px);
  padding: clamp(22px, 3vw, 34px);
  background: var(--ink-900);
  color: var(--chalk);
}

.page-about .about-next__lead {
  margin: 0 0 18px;
  font-family: var(--font-display);
  font-size: clamp(1.2rem, 2.2vw, 1.6rem);
  line-height: 1.4;
  color: var(--chalk);
}

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

.page-about .about-next__note {
  margin: 18px 0 0;
  padding-top: 16px;
  border-top: 1px solid var(--line-dark);
  font-size: .88rem;
  line-height: 1.72;
  color: rgba(255, 255, 255, .76);
  max-width: 64ch;
}