.page-about {
  --about-rail: 84px;
  color: var(--on-dark);
  padding-bottom: 80px;
}

/* 面包屑 */
.page-about .about-crumb {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 18px 20px 4px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: var(--fs-13);
  color: var(--tick);
}
.page-about .about-crumb a {
  color: var(--tick);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 140ms var(--ease), border-color 140ms var(--ease);
}
.page-about .about-crumb a:hover {
  color: var(--on-dark);
  border-bottom-color: var(--signal-top);
}
.page-about .about-crumb [aria-current="page"] {
  color: var(--on-dark);
}

/* 首屏 */
.page-about .about-hero {
  padding: 14px 0 40px;
}
.page-about .about-hero__inner {
  max-width: var(--wrap);
  margin: 0 auto;
  padding-inline: 20px;
  display: grid;
  gap: 20px;
  min-width: 0;
}
.page-about .about-hero .eyebrow {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.14em;
  color: var(--signal-third);
}
.page-about .about-hero h1 {
  margin: 0;
  font-size: clamp(32px, 6.2vw, var(--fs-76));
  line-height: 1.04;
  letter-spacing: -0.02em;
  font-weight: 800;
  max-width: 20ch;
}
.page-about .about-lede {
  margin: 0;
  font-size: var(--fs-17);
  line-height: 1.85;
  color: #C6D2E2;
  max-width: 42em;
}
.page-about .about-hero__media {
  margin: 8px 0 0;
}
.page-about .about-hero__media img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 7;
  object-fit: cover;
  border-radius: 3px;
  filter: saturate(0.92) contrast(1.04);
}

/* 出血色带 */
.page-about .band-wrap {
  max-width: var(--wrap);
  margin: 0 auto;
  padding-inline: 20px;
}
.page-about .bleed-band {
  display: grid;
  grid-template-columns: 1.3fr 1fr 0.7fr;
  height: 8px;
  margin: 0 -20px 34px;
}
.page-about .bleed-band span {
  display: block;
}
.page-about .bleed-band span:nth-child(1) { background: var(--signal-top); }
.page-about .bleed-band span:nth-child(2) { background: var(--signal-mid); }
.page-about .bleed-band span:nth-child(3) { background: var(--signal-third); }

/* 主栅格：刻度轴 + 内容流 */
.page-about .about-grid {
  max-width: var(--wrap);
  margin: 0 auto;
  padding-inline: 20px;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  min-width: 0;
}
.page-about .about-flow {
  min-width: 0;
}

/* 左侧刻度轴 */
.page-about .scale-rail {
  display: none;
}
.page-about .rail-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 18px;
}
.page-about .rail-link {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--tick);
  font-size: var(--fs-12);
  transition: color 140ms var(--ease);
}
.page-about .rail-link .rail-num {
  font-family: var(--font-mono);
  font-weight: 700;
  letter-spacing: 0.06em;
  font-variant-numeric: tabular-nums;
}
.page-about .rail-link .rail-tick {
  display: block;
  width: 16px;
  height: 1px;
  background: currentColor;
  opacity: 0.5;
  transition: width 140ms var(--ease), opacity 140ms var(--ease);
}
.page-about .rail-link:hover {
  color: var(--on-dark);
}
.page-about .rail-link[aria-current="true"] {
  color: var(--score);
}
.page-about .rail-link[aria-current="true"] .rail-tick {
  width: 34px;
  opacity: 1;
}

/* 章节通用 */
.page-about .about-section {
  padding: 36px 0;
}
.page-about .about-section + .about-section {
  border-top: 1px solid var(--line-dark);
}
.page-about .sec-head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 16px;
}
.page-about .sec-num {
  flex: none;
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  font-weight: 700;
  letter-spacing: 0.12em;
  color: var(--score);
}
.page-about .sec-title {
  margin: 0;
  font-size: clamp(23px, 3.2vw, var(--fs-32));
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -0.01em;
}
.page-about .about-section p {
  margin: 0 0 15px;
  font-size: var(--fs-15);
  line-height: 1.85;
  color: #C6D2E2;
}
.page-about .about-section p:last-child {
  margin-bottom: 0;
}
.page-about .about-narrow {
  max-width: 640px;
}
.page-about .about-text {
  max-width: 640px;
}
.page-about .note-line {
  margin-top: 18px;
  padding-top: 12px;
  border-top: 1px solid var(--line-dark);
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.04em;
  color: var(--tick);
}
.page-about .link-arrow {
  color: var(--score);
  text-decoration: none;
  border-bottom: 1px solid rgba(92, 255, 158, 0.4);
}
.page-about .link-arrow:hover {
  border-bottom-color: var(--score);
}

/* 版本阶梯 */
.page-about .version-chart {
  margin: 22px 0 22px;
  padding: 16px 6px 10px;
  background: var(--ink-800);
  border: 1px solid var(--line-dark);
  border-radius: 3px;
}
.page-about .version-chart svg {
  display: block;
  width: 100%;
  height: auto;
}
.page-about .version-chart .vc-axis {
  stroke: var(--line-dark);
  stroke-width: 1;
}
.page-about .version-chart .vc-bar {
  fill: rgba(140, 151, 171, 0.3);
}
.page-about .version-chart .vc-bar--key {
  fill: var(--signal-mid);
}
.page-about .version-chart .vc-bar--latest {
  fill: var(--signal-top);
}
.page-about .version-chart .vc-label {
  fill: var(--tick);
  font-family: var(--font-mono);
  font-size: 14px;
}
.page-about .version-chart .vc-label--key {
  fill: var(--signal-mid);
}
.page-about .version-chart .vc-label--latest {
  fill: var(--signal-top);
}
.page-about .version-chart .vc-note {
  fill: #C6D2E2;
  font-size: 13px;
}
.page-about .version-chart figcaption {
  margin-top: 10px;
  padding-inline: 6px;
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  line-height: 1.7;
  color: var(--tick);
}

/* 版本说明 */
.page-about .version-notes {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 16px;
}
.page-about .vn {
  padding: 2px 0 2px 16px;
  border-left: 3px solid var(--signal-mid);
}
.page-about .vn--top {
  border-left-color: var(--signal-top);
}
.page-about .vn-ver {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: var(--fs-17);
  letter-spacing: 0.02em;
  color: var(--on-dark);
}

/* 流程 */
.page-about .process-grid {
  display: grid;
  gap: 26px;
  margin-top: 6px;
}
.page-about .flow-list {
  list-style: none;
  margin: 0;
  padding: 0;
  min-width: 0;
}
.page-about .flow-step {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 14px;
  padding: 16px 0;
  border-top: 1px solid var(--line-dark);
}
.page-about .flow-step:last-child {
  border-bottom: 1px solid var(--line-dark);
}
.page-about .flow-idx {
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: var(--fs-22);
  line-height: 1;
  color: var(--signal-top);
}
.page-about .flow-body h3 {
  margin: 0 0 8px;
  font-size: var(--fs-17);
  font-weight: 700;
  letter-spacing: 0.01em;
}
.page-about .flow-body p {
  margin: 0 0 10px;
}
.page-about .flow-step .flow-out {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  line-height: 1.7;
  color: var(--tick);
}
.page-about .flow-out span {
  display: inline-block;
  margin-right: 8px;
  padding: 1px 6px;
  border-radius: 2px;
  background: rgba(92, 255, 158, 0.14);
  color: var(--score);
  letter-spacing: 0.08em;
}
.page-about .process-media {
  margin: 0;
}
.page-about .process-media img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
  border-radius: 3px;
}
.page-about .process-media figcaption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  line-height: 1.7;
  color: var(--tick);
}

/* 团队 */
.page-about .team-grid {
  display: grid;
  gap: 28px;
  margin-top: 16px;
}
.page-about .team-ring {
  margin: 0;
  text-align: center;
}
.page-about .team-ring svg {
  width: 100%;
  max-width: 232px;
  height: auto;
}
.page-about .team-ring .ring--a { stroke: var(--score); }
.page-about .team-ring .ring--b { stroke: rgba(92, 255, 158, 0.55); }
.page-about .team-ring .ring--c { stroke: rgba(92, 255, 158, 0.25); }
.page-about .team-ring figcaption {
  margin-top: 14px;
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  letter-spacing: 0.06em;
  color: var(--tick);
}
.page-about .team-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 18px;
}
.page-about .team-list li {
  display: grid;
  grid-template-columns: 12px minmax(0, 1fr);
  gap: 14px;
}
.page-about .team-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  margin-top: 6px;
}
.page-about .team-dot--a { background: var(--score); }
.page-about .team-dot--b { background: rgba(92, 255, 158, 0.55); }
.page-about .team-dot--c { background: rgba(92, 255, 158, 0.25); }
.page-about .team-list h3 {
  margin: 0 0 6px;
  font-size: var(--fs-17);
  font-weight: 700;
  letter-spacing: 0.01em;
}
.page-about .team-list h3 .num {
  color: var(--on-dark);
  font-family: var(--font-mono);
}
.page-about .team-list p {
  margin: 0;
}

/* 分级与节奏 */
.page-about .tier-figure {
  margin: 18px 0 0;
}
.page-about .tier-figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 12 / 7;
  object-fit: cover;
  border-radius: 3px;
}
.page-about .tier-figure figcaption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  line-height: 1.7;
  color: var(--tick);
}
.page-about .tier-list {
  list-style: none;
  margin: 18px 0 0;
  padding: 0;
  display: grid;
  gap: 10px;
}
.page-about .tier-list li {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  padding: 12px 14px;
  border: 1px solid var(--line-dark);
  border-radius: 3px;
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  color: var(--tick);
}
.page-about .tier-list .num {
  color: var(--on-dark);
  font-weight: 800;
  font-size: var(--fs-17);
}
.page-about .rhythm-grid {
  display: grid;
  gap: 14px;
  margin-top: 24px;
}
.page-about .rhythm-item {
  padding: 18px 16px 20px;
  background: var(--ink-800);
  border: 1px solid var(--line-dark);
  border-top: 3px solid var(--score);
  border-radius: 3px;
}
.page-about .rhythm-item h3 {
  margin: 0 0 10px;
  font-size: var(--fs-17);
  font-weight: 700;
  line-height: 1.4;
}
.page-about .rhythm-item p {
  margin: 0;
  font-size: var(--fs-15);
  line-height: 1.8;
  color: #C6D2E2;
}

/* 暖纸区 */
.page-about .paper-section {
  background: var(--paper);
  color: var(--on-paper);
  padding: 32px 22px 36px;
  margin: 40px -20px 0 0;
  border-radius: 3px;
}
.page-about .paper-section + .about-section {
  border-top: 0;
}
.page-about .paper-section .sec-num {
  color: var(--alert);
}
.page-about .paper-section .sec-title {
  color: var(--on-paper);
}
.page-about .paper-section p {
  color: #2C3543;
  font-size: var(--fs-17);
}
.page-about .paper-section a {
  color: var(--on-paper);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  text-decoration-color: var(--paper-line);
}
.page-about .paper-section a:hover {
  text-decoration-color: var(--on-paper);
}
.page-about .boundary-list {
  list-style: none;
  margin: 20px 0;
  padding: 0;
}
.page-about .boundary-list li {
  padding: 14px 0;
  border-bottom: 1px solid var(--paper-line);
  font-size: var(--fs-15);
  line-height: 1.8;
  color: #2C3543;
}
.page-about .boundary-list li:first-child {
  border-top: 1px solid var(--paper-line);
}
.page-about .boundary-list strong {
  font-weight: 700;
  color: var(--on-paper);
}

/* 桌面端栅格与尺寸 */
@media (min-width: 720px) {
  .page-about .tier-list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .rhythm-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .version-notes {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 22px;
  }
}

@media (min-width: 880px) {
  .page-about .team-grid {
    grid-template-columns: 250px minmax(0, 1fr);
    column-gap: 46px;
    align-items: center;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    padding: 20px 0 48px;
  }
  .page-about .process-grid {
    grid-template-columns: minmax(0, 1fr) 300px;
    column-gap: 38px;
    align-items: start;
  }
  .page-about .about-section {
    padding: 44px 0;
  }
}

@media (min-width: 1024px) {
  .page-about .about-grid {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    column-gap: 30px;
  }
  .page-about .scale-rail {
    display: block;
    position: sticky;
    top: calc(var(--header-h) + 26px);
    align-self: start;
    padding-top: 52px;
  }
  .page-about .paper-section {
    padding: 44px 40px 48px;
    margin-right: -20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .rail-link,
  .page-about .rail-link .rail-tick,
  .page-about .about-crumb a {
    transition: none;
  }
}