.page-about {
  --about-gap: clamp(18px, 2.6vw, 32px);
  --about-line: rgba(27, 59, 92, 0.9);
  --about-pad: clamp(20px, 2.6vw, 32px);
  display: block;
  position: relative;
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding-block: clamp(24px, 4vw, 48px) clamp(40px, 6vw, 84px);
  border-bottom: 1px solid var(--line-3);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--line-3) 1px, transparent 1px),
    linear-gradient(90deg, var(--line-3) 1px, transparent 1px);
  background-size: 72px 72px;
  mask-image: linear-gradient(180deg, #000 0%, transparent 88%);
  pointer-events: none;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  top: -14%;
  right: -18%;
  width: min(620px, 78vw);
  aspect-ratio: 1 / 1;
  background: linear-gradient(135deg, rgba(53, 242, 224, 0.18) 0%, rgba(138, 91, 255, 0.08) 42%, transparent 72%);
  clip-path: polygon(0 0, 100% 0, 100% 58%, 0 100%);
  transform: rotate(14deg);
  pointer-events: none;
}

.page-about .about-hero__grid {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(26px, 4vw, 46px);
}

.page-about .about-hero__coord {
  margin: 18px 0 12px;
  font-size: 12px;
  letter-spacing: 0.24em;
  color: var(--c-amber);
}

.page-about .about-hero__title {
  margin: 0 0 18px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(28px, 5.2vw, 46px);
  line-height: 1.22;
  letter-spacing: 0.04em;
  color: var(--c-paper);
  max-width: 22ch;
}

.page-about .about-hero__lead {
  max-width: 62ch;
  color: var(--ink-2);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

.page-about .about-hero__panel {
  align-self: start;
  padding: var(--about-pad);
  background: linear-gradient(180deg, rgba(12, 44, 74, 0.94), rgba(6, 26, 46, 0.5));
}

.page-about .about-stats {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
}

.page-about .about-stat {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  padding-block: 12px;
  border-bottom: 1px dashed var(--line-2);
}

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

.page-about .about-stat__num {
  font-family: var(--font-mono);
  font-size: clamp(20px, 3vw, 26px);
  font-weight: 700;
  color: var(--c-cyan);
  letter-spacing: 0.02em;
}

.page-about .about-stat__label {
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--ink-2);
  text-align: right;
}

/* ---------- 章节 01：起点 ---------- */
.page-about .about-steps {
  display: grid;
  gap: var(--about-gap);
  margin-top: clamp(28px, 4vw, 48px);
}

.page-about .about-step {
  position: relative;
  padding: 22px 20px 24px 26px;
  border: 1px solid var(--line-3);
  border-left: 2px solid var(--c-cyan);
  background: linear-gradient(135deg, rgba(12, 44, 74, 0.55), rgba(6, 26, 46, 0.15));
  transition: border-color var(--t-fast) var(--ease), transform var(--t-fast) var(--ease);
}

.page-about .about-step:hover {
  border-color: var(--c-orange);
  transform: translateY(-3px);
}

.page-about .about-step__num {
  margin: 0 0 10px;
  font-size: 12px;
  letter-spacing: 0.22em;
  color: var(--c-amber);
}

.page-about .about-step__title {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-size: clamp(17px, 2.2vw, 20px);
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--c-paper);
}

.page-about .about-step p {
  margin: 0;
  color: var(--ink-2);
  font-size: 15px;
  line-height: 1.8;
}

/* ---------- 章节 02：覆盖 ---------- */
.page-about .about-coverage__figure {
  margin: clamp(26px, 4vw, 44px) 0 0;
}

.page-about .about-regions {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 26px 0 0;
  padding: 0;
}

.page-about .about-region {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border: 1px solid var(--line);
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--ink-2);
  background: rgba(12, 44, 74, 0.5);
  transition: border-color var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}

.page-about .about-region:hover {
  border-color: var(--c-cyan);
  color: var(--c-paper);
}

.page-about .about-region__dot {
  width: 7px;
  height: 7px;
  background: var(--c-cyan);
  transform: rotate(45deg);
  box-shadow: 0 0 8px rgba(53, 242, 224, 0.7);
}

.page-about .about-region:nth-child(even) .about-region__dot {
  background: var(--c-amber);
  box-shadow: 0 0 8px rgba(255, 194, 75, 0.6);
}

.page-about .about-node-parts {
  display: grid;
  gap: var(--about-gap);
  margin-top: clamp(28px, 4vw, 46px);
}

.page-about .about-node-part {
  padding-top: 18px;
  border-top: 1px solid var(--line-2);
}

.page-about .about-node-part__key {
  margin: 0 0 10px;
  font-size: 13px;
  letter-spacing: 0.2em;
  color: var(--c-cyan);
}

.page-about .about-node-part__title {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--c-paper);
}

.page-about .about-node-part p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-2);
}

/* ---------- 章节 03：文档 ---------- */
.page-about .about-docs {
  display: grid;
  gap: clamp(26px, 4vw, 44px);
}

.page-about .about-topics {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 24px 0 0;
  padding: 0;
}

.page-about .about-facts {
  margin: clamp(26px, 3.4vw, 38px) 0 0;
  display: grid;
  gap: 0;
}

.page-about .about-fact {
  padding: 16px 0;
  border-bottom: 1px solid var(--line-3);
}

.page-about .about-fact:first-child {
  border-top: 1px solid var(--line-3);
}

.page-about .about-fact dt {
  font-family: var(--font-display);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--c-amber);
  margin-bottom: 6px;
}

.page-about .about-fact dd {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-2);
}

.page-about .about-docs__figure {
  margin: 0;
}

/* ---------- 章节 04：历程 ---------- */
.page-about .about-stages__figure {
  margin: clamp(26px, 4vw, 44px) 0 0;
}

.page-about .about-timeline {
  list-style: none;
  display: grid;
  gap: var(--about-gap);
  margin: clamp(28px, 4vw, 44px) 0 0;
  padding: 0;
}

.page-about .about-timeline__item {
  position: relative;
  padding-left: 22px;
}

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 26px;
  width: 9px;
  height: 9px;
  background: var(--c-cyan);
  transform: rotate(45deg);
  box-shadow: 0 0 10px rgba(53, 242, 224, 0.66);
}

.page-about .about-stage {
  border: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(12, 44, 74, 0.78), rgba(6, 26, 46, 0.34));
  transition: border-color var(--t-fast) var(--ease), background-color var(--t-fast) var(--ease);
}

.page-about .about-stage:hover {
  border-color: var(--c-orange);
}

.page-about .about-stage[open] {
  border-color: var(--c-amber);
}

.page-about .about-stage__summary {
  display: grid;
  gap: 6px;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-stage__num {
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--c-amber);
}

.page-about .about-stage__title {
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--c-paper);
}

.page-about .about-stage__hint {
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--ink-3);
}

.page-about .about-stage[open] .about-stage__hint {
  color: var(--c-cyan);
}

.page-about .about-stage__text {
  margin: 0;
  padding: 0 18px 18px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-2);
  border-left: 2px solid var(--c-cyan);
  margin-left: 18px;
  padding-left: 14px;
}

/* ---------- 章节 05：节奏 ---------- */
.page-about .about-cadence {
  list-style: none;
  display: grid;
  gap: 0;
  margin: clamp(26px, 4vw, 42px) 0 0;
  padding: 0;
  border-top: 1px solid var(--line-2);
}

.page-about .about-cadence__row {
  display: grid;
  gap: 8px;
  padding: 22px 0;
  border-bottom: 1px solid var(--line-2);
}

.page-about .about-cadence__key {
  margin: 0;
  font-size: 13px;
  letter-spacing: 0.2em;
  color: var(--c-cyan);
}

.page-about .about-cadence__title {
  margin: 0 0 6px;
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--c-paper);
}

.page-about .about-cadence__body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-2);
  max-width: 68ch;
}

.page-about .about-rhythm__note {
  margin: 26px 0 0;
  font-size: 15px;
  line-height: 1.9;
  color: var(--ink-2);
}

/* ---------- 章节 06：班底 ---------- */
.page-about .about-team {
  display: grid;
  gap: clamp(26px, 4vw, 42px);
}

.page-about .about-team__list {
  list-style: none;
  display: grid;
  gap: 14px;
  margin: 0;
  padding: 0;
}

.page-about .about-team__item {
  padding: 18px 18px 20px;
  border: 1px solid var(--line-3);
  background: rgba(12, 44, 74, 0.42);
  transition: border-color var(--t-fast) var(--ease);
}

.page-about .about-team__item:hover {
  border-color: var(--c-amber);
}

.page-about .about-team__role {
  margin: 0 0 8px;
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--c-amber);
}

.page-about .about-team__name {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--c-paper);
}

.page-about .about-team__item p:last-child {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--ink-2);
}

/* ---------- 尾段 ---------- */
.page-about .about-next {
  border-top: 1px solid var(--line-2);
}

.page-about .about-next__title {
  margin: 0 0 20px;
  font-family: var(--font-display);
  font-size: clamp(19px, 2.6vw, 24px);
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--c-paper);
}

.page-about .about-next__links {
  display: grid;
  gap: 14px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .about-node-parts {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-cadence__row {
    grid-template-columns: 120px minmax(0, 1fr);
    align-items: start;
    gap: 24px;
  }

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

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

@media (min-width: 940px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.6fr) minmax(280px, 1fr);
    align-items: start;
  }

  .page-about .about-hero__main {
    padding-right: clamp(12px, 3vw, 40px);
  }

  .page-about .about-steps {
    grid-template-columns: 1.05fr 0.9fr 1fr;
    align-items: start;
  }

  .page-about .about-step:nth-child(2) {
    margin-top: 46px;
  }

  .page-about .about-step:nth-child(3) {
    margin-top: 92px;
  }

  .page-about .about-docs {
    grid-template-columns: minmax(0, 1.45fr) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-docs__figure {
    margin-top: 56px;
  }

  .page-about .about-timeline {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    position: relative;
    padding-top: 26px;
  }

  .page-about .about-timeline::before {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    top: 5px;
    height: 2px;
    background: linear-gradient(90deg, var(--c-cyan) 0%, var(--c-amber) 62%, var(--c-orange) 100%);
    opacity: 0.55;
  }

  .page-about .about-timeline__item {
    padding-left: 0;
  }

  .page-about .about-timeline__item::before {
    top: -26px;
    left: 0;
  }

  .page-about .about-team {
    grid-template-columns: minmax(0, 0.85fr) minmax(0, 1.15fr);
    align-items: start;
  }
}

@media (min-width: 1180px) {
  .page-about .about-step:nth-child(3) {
    margin-top: 128px;
  }

  .page-about .about-docs__figure {
    margin-top: 84px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-step,
  .page-about .about-stage,
  .page-about .about-region,
  .page-about .about-team__item {
    transition: none;
  }

  .page-about .about-step:hover {
    transform: none;
  }
}