.page-about {
  --a-tint-1: rgba(26, 106, 135, 0.16);
  --a-tint-2: rgba(26, 106, 135, 0.3);
  --a-tint-3: rgba(26, 106, 135, 0.44);
  --a-warm-tint: rgba(255, 122, 41, 0.18);
  background-color: var(--bg-deep);
  color: var(--white);
  overflow-x: clip;
}

/* ============ 首屏 ============ */
.page-about .a-hero {
  position: relative;
  padding-top: calc(var(--header-h) + clamp(20px, 4vw, 48px));
  padding-bottom: clamp(40px, 6vw, 80px);
  background:
    radial-gradient(115% 85% at 84% 2%, rgba(255, 122, 41, 0.16), transparent 58%),
    radial-gradient(95% 75% at -8% 98%, rgba(26, 106, 135, 0.36), transparent 62%),
    var(--bg-deep);
}

.page-about .a-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0.5;
  background-image:
    linear-gradient(rgba(30, 74, 95, 0.4) 1px, transparent 1px),
    linear-gradient(90deg, rgba(30, 74, 95, 0.4) 1px, transparent 1px);
  background-size: 72px 72px;
  -webkit-mask-image: radial-gradient(80% 70% at 55% 25%, #000 0%, transparent 100%);
  mask-image: radial-gradient(80% 70% at 55% 25%, #000 0%, transparent 100%);
}

.page-about .a-hero .wrap {
  position: relative;
  z-index: 1;
}

.page-about .a-hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 5vw, 52px);
  align-items: center;
  margin-top: clamp(20px, 3vw, 32px);
}

@media (min-width: 960px) {
  .page-about .a-hero-grid {
    grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.92fr);
  }
}

.page-about .a-hero-copy h1 {
  margin: 10px 0 0;
  font-size: clamp(30px, 5.6vw, 56px);
  line-height: 1.14;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--white);
}

.page-about .a-hero-copy .lede {
  margin-top: 20px;
  max-width: 60ch;
}

.page-about .a-hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.page-about .a-hero-figure {
  position: relative;
  margin: 0;
}

.page-about .a-hero-media {
  aspect-ratio: 3 / 2;
}

.page-about .a-hero-badge {
  position: absolute;
  left: -8px;
  bottom: 20px;
  z-index: 3;
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  padding: 8px 14px;
  background: var(--bg-float);
  border: 1px solid rgba(255, 122, 41, 0.55);
  color: var(--orange-soft);
  font-size: 13px;
  letter-spacing: 0.04em;
}

.page-about .a-hero-badge .num {
  font-size: 16px;
  color: var(--orange);
}

/* 首屏章节预览轨道 */
.page-about .a-toc {
  list-style: none;
  margin: clamp(34px, 5vw, 56px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

@media (min-width: 780px) {
  .page-about .a-toc {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 1080px) {
  .page-about .a-toc {
    grid-template-columns: repeat(6, minmax(0, 1fr));
  }
}

.page-about .a-toc-item {
  background: var(--bg-deep);
}

.page-about .a-toc-item a {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 16px 14px 20px;
  text-decoration: none;
  color: var(--silver);
  box-shadow: inset 2px 0 0 transparent;
  transition: background 0.22s ease, color 0.22s ease, box-shadow 0.22s ease;
}

.page-about .a-toc-item a:hover,
.page-about .a-toc-item a:focus-visible {
  background: var(--bg-panel);
  color: var(--white);
  box-shadow: inset 2px 0 0 var(--orange);
}

.page-about .a-toc-num {
  font-size: 15px;
  color: var(--teal);
  letter-spacing: 0.06em;
}

.page-about .a-toc-item a:hover .a-toc-num {
  color: var(--orange);
}

.page-about .a-toc-label {
  font-size: 14px;
  line-height: 1.4;
}

/* ============ 章节通用骨架 ============ */
.page-about .a-sec {
  position: relative;
  padding-block: clamp(48px, 7vw, 96px);
  border-top: 1px solid var(--line);
}

.page-about .a-sec--a {
  background: var(--bg-deep);
}

.page-about .a-sec--b {
  background: linear-gradient(180deg, var(--bg-panel) 0%, rgba(11, 51, 70, 0.82) 100%);
}

.page-about .a-sec-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
}

@media (min-width: 880px) {
  .page-about .a-sec-grid {
    grid-template-columns: 120px minmax(0, 1fr);
    gap: clamp(28px, 4vw, 56px);
  }
}

.page-about .a-marker {
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 14px;
}

@media (min-width: 880px) {
  .page-about .a-marker {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
  }
}

.page-about .a-marker-num {
  font-family: var(--font-mono);
  font-size: clamp(38px, 7vw, 68px);
  font-weight: 700;
  line-height: 0.9;
  letter-spacing: -0.04em;
  color: var(--teal);
}

.page-about .a-node {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--orange);
  box-shadow: 0 0 0 4px rgba(255, 122, 41, 0.16);
  flex: none;
}

.page-about .a-thread {
  display: none;
}

@media (min-width: 880px) {
  .page-about .a-thread {
    display: block;
    flex: 1;
    width: 1px;
    min-height: 56px;
    background: linear-gradient(180deg, var(--line) 0%, rgba(30, 74, 95, 0) 100%);
  }
}

.page-about .a-sec-body {
  max-width: 76ch;
}

.page-about .a-sec-body .sec-title {
  margin: 12px 0 20px;
  font-size: clamp(24px, 3.6vw, 38px);
  line-height: 1.2;
  font-weight: 700;
}

.page-about .a-sec-body > p {
  margin: 0 0 16px;
  font-size: 17px;
  line-height: 1.8;
  color: var(--silver);
}

.page-about .a-sec-body > p:last-child {
  margin-bottom: 0;
}

/* ============ 版本演进 ============ */
.page-about .a-ver {
  list-style: none;
  margin: clamp(24px, 3vw, 36px) 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .a-ver-item {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 8px;
  padding: 20px 22px;
  border-left: 3px solid var(--teal);
  background: linear-gradient(100deg, var(--a-tint-1) 0%, rgba(26, 106, 135, 0.02) 100%);
  transition: border-color 0.22s ease, background 0.22s ease;
}

@media (min-width: 620px) {
  .page-about .a-ver-item {
    grid-template-columns: 88px minmax(0, 1fr);
    gap: 20px;
    align-items: start;
  }
}

.page-about .a-ver-item:nth-child(1) {
  border-left-color: rgba(26, 106, 135, 0.65);
}

.page-about .a-ver-item:nth-child(2) {
  border-left-color: var(--teal);
  background: linear-gradient(100deg, var(--a-tint-2) 0%, rgba(26, 106, 135, 0.03) 100%);
}

.page-about .a-ver-item:nth-child(3) {
  border-left-color: var(--orange-soft);
  background: linear-gradient(100deg, var(--a-tint-3) 0%, rgba(26, 106, 135, 0.05) 100%);
}

.page-about .a-ver-item:nth-child(4) {
  border-left-color: var(--orange);
  background: linear-gradient(100deg, var(--a-warm-tint) 0%, rgba(26, 106, 135, 0.06) 100%);
}

.page-about .a-ver-item:hover {
  border-left-color: var(--orange);
}

.page-about .a-ver-year {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 700;
  color: var(--orange);
  letter-spacing: 0.02em;
}

.page-about .a-ver-title {
  margin: 0 0 8px;
  font-size: 18px;
  font-weight: 700;
  color: var(--white);
}

.page-about .a-ver-copy p {
  margin: 0;
  font-size: 16px;
  line-height: 1.78;
  color: var(--silver);
}

/* ============ 图片容器 ============ */
.page-about .a-figure {
  margin: clamp(28px, 4vw, 44px) 0 0;
}

.page-about .a-figure--wide {
  margin-top: clamp(32px, 5vw, 52px);
}

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

.page-about .media-frame-caption {
  color: var(--silver-dim);
}

/* ============ 内容生产流程 ============ */
.page-about .a-flow {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin-top: clamp(24px, 3vw, 36px);
  background: var(--line);
  border: 1px solid var(--line);
}

@media (min-width: 700px) {
  .page-about .a-flow {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1080px) {
  .page-about .a-flow {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .a-flow-step {
  background: var(--bg-deep);
  padding: 20px 18px 24px;
  border-top: 2px solid transparent;
  transition: border-color 0.22s ease, background 0.22s ease;
}

.page-about .a-flow-step:hover {
  border-top-color: var(--orange);
  background: var(--bg-float);
}

.page-about .a-flow-no {
  display: block;
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--teal);
}

.page-about .a-flow-step h3 {
  margin: 10px 0 8px;
  font-size: 17px;
  font-weight: 700;
  color: var(--white);
}

.page-about .a-flow-step p {
  margin: 0;
  font-size: 15px;
  line-height: 1.72;
  color: var(--silver);
}

/* ============ 数据条 ============ */
.page-about .a-facts {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
  margin-top: clamp(28px, 4vw, 44px);
}

@media (min-width: 700px) {
  .page-about .a-facts {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1px;
    background: var(--line);
    border: 1px solid var(--line);
  }
}

.page-about .a-fact {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 26px 20px 24px;
  background: var(--bg-panel);
  border-top: 2px solid var(--orange);
}

.page-about .a-fact-num {
  font-family: var(--font-mono);
  font-size: clamp(30px, 4vw, 42px);
  font-weight: 700;
  line-height: 1;
  color: var(--orange);
  letter-spacing: -0.02em;
}

.page-about .a-fact-label {
  font-size: 14px;
  line-height: 1.7;
  color: var(--silver);
}

/* ============ 更新节奏 ============ */
.page-about .a-rhythm {
  list-style: none;
  margin: clamp(24px, 3vw, 36px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 14px;
}

@media (min-width: 860px) {
  .page-about .a-rhythm {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: clamp(16px, 2vw, 28px);
  }
}

.page-about .a-rhythm-item {
  position: relative;
  padding: 22px 20px 22px 24px;
  background: var(--bg-float);
  border-left: 2px solid var(--line);
  transition: border-color 0.22s ease;
}

.page-about .a-rhythm-item:hover {
  border-left-color: var(--green);
}

.page-about .a-rhythm-num {
  font-family: var(--font-mono);
  font-size: clamp(30px, 4vw, 40px);
  font-weight: 700;
  line-height: 1;
  color: var(--green);
  letter-spacing: -0.02em;
}

.page-about .a-rhythm-unit {
  margin-left: 8px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--silver-dim);
}

.page-about .a-rhythm-item p {
  margin: 14px 0 0;
  font-size: 15px;
  line-height: 1.74;
  color: var(--silver);
}

.page-about .a-standard {
  margin-top: clamp(28px, 4vw, 44px);
  padding: clamp(22px, 3vw, 32px);
  background: linear-gradient(140deg, rgba(26, 106, 135, 0.34) 0%, rgba(11, 51, 70, 0.4) 100%);
  border: 1px solid var(--line);
}

.page-about .a-standard-title {
  margin: 0 0 14px;
  font-size: 18px;
  font-weight: 700;
  color: var(--white);
}

.page-about .a-standard p {
  margin: 0 0 12px;
  font-size: 16px;
  line-height: 1.8;
  color: var(--silver);
}

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

/* ============ 协作生态点阵 ============ */
.page-about .a-cluster {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
  margin-top: clamp(26px, 3vw, 38px);
}

@media (min-width: 760px) {
  .page-about .a-cluster {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 20px;
  }
}

.page-about .a-cluster-item {
  padding: 22px 20px;
  background: var(--bg-deep);
  border: 1px solid var(--line);
  border-top: 2px solid var(--teal);
}

.page-about .a-cluster-label {
  margin: 0;
  font-size: 16px;
  color: var(--white);
}

.page-about .a-cluster-label .num {
  font-size: 24px;
  color: var(--orange);
  margin-right: 4px;
}

.page-about .a-cluster-note {
  margin: 10px 0 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--silver-dim);
}

.page-about .a-dots {
  list-style: none;
  margin: 16px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.page-about .a-dots li {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--teal);
  transition: background 0.2s ease, transform 0.2s ease;
}

.page-about .a-dots li:hover {
  background: var(--green);
  transform: scale(1.4);
}

.page-about .a-dots--warm li {
  background: rgba(255, 122, 41, 0.72);
}

.page-about .a-dots--warm li:hover {
  background: var(--orange);
}

/* ============ 认可条目 ============ */
.page-about .a-honor {
  list-style: none;
  margin: clamp(24px, 3vw, 36px) 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .a-honor-item {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 8px;
  padding: 22px 22px;
  background: var(--bg-panel);
  transition: background 0.22s ease, box-shadow 0.22s ease;
}

@media (min-width: 720px) {
  .page-about .a-honor-item {
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 24px;
    align-items: baseline;
  }
}

.page-about .a-honor-item:hover {
  background: var(--bg-float);
  box-shadow: inset 3px 0 0 var(--orange);
}

.page-about .a-honor-tag {
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--orange-soft);
}

.page-about .a-honor-item p {
  margin: 0;
  font-size: 16px;
  line-height: 1.8;
  color: var(--silver);
}

/* ============ 收尾 ============ */
.page-about .a-cta {
  position: relative;
  padding-block: clamp(44px, 6vw, 84px);
  background: linear-gradient(120deg, var(--bg-panel) 0%, var(--bg-float) 100%);
  border-top: 1px solid var(--line);
}

.page-about .a-cta::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--orange) 0%, var(--amber) 50%, var(--green) 100%);
}

.page-about .a-cta-inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 26px;
  align-items: center;
}

@media (min-width: 900px) {
  .page-about .a-cta-inner {
    grid-template-columns: minmax(0, 1.4fr) minmax(0, 0.6fr);
    gap: 48px;
  }
}

.page-about .a-cta-title {
  margin: 12px 0 14px;
  font-size: clamp(22px, 3.2vw, 32px);
  line-height: 1.25;
  font-weight: 700;
  color: var(--white);
}

.page-about .a-cta-copy p {
  margin: 0;
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.8;
  color: var(--silver);
}

.page-about .a-cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

@media (min-width: 900px) {
  .page-about .a-cta-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .page-about .a-cta-actions .btn {
    text-align: center;
  }
}