.page-about {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--ff-body);
  padding-bottom: clamp(40px, 7vw, 84px);
  overflow-x: clip;
}

.page-about .about-crumb {
  padding-top: clamp(10px, 2.2vw, 22px);
}

/* 首屏 */
.page-about .hero {
  display: grid;
  gap: clamp(26px, 5vw, 52px);
  padding-block: clamp(22px, 4vw, 42px) clamp(34px, 6vw, 72px);
  align-items: center;
}

.page-about .coord-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 18px;
  padding: 6px 14px;
  border-radius: var(--r-pill);
  background: var(--mist);
  color: var(--ocean);
  font-size: 12px;
  letter-spacing: 0.08em;
}

.page-about .coord-tag .dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--signal);
}

.page-about .hero h1 {
  margin: 0 0 20px;
  font-family: var(--ff-display);
  font-weight: 900;
  font-size: clamp(32px, 6.2vw, 66px);
  line-height: 1.07;
  letter-spacing: -0.02em;
  color: var(--ocean);
}

.page-about .hero-lede {
  margin: 0 0 28px;
  font-family: var(--ff-serif);
  font-size: clamp(17px, 2vw, 21px);
  line-height: 1.78;
  color: var(--ink);
  max-width: 36em;
}

.page-about .hero-stats {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px 18px;
}

.page-about .hero-stats li {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding-top: 12px;
  border-top: 2px solid var(--mist);
}

.page-about .stat-num {
  font-family: var(--ff-mono);
  font-variant-numeric: tabular-nums;
  font-size: 26px;
  font-weight: 700;
  color: var(--ocean);
  line-height: 1.1;
}

.page-about .stat-key {
  font-size: 13px;
  line-height: 1.5;
  color: var(--ink);
  opacity: 0.78;
}

.page-about .hero-visual {
  display: flex;
  justify-content: center;
}

.page-about .coord-visual {
  width: 100%;
  max-width: 520px;
  height: auto;
}

.page-about .arc {
  fill: none;
  stroke: var(--ridge);
  stroke-width: 1.1;
  opacity: 0.5;
}

.page-about .arc--inner {
  stroke: var(--data);
  opacity: 0.55;
}

.page-about .arc--outer {
  stroke: var(--ocean);
  opacity: 0.4;
}

.page-about .spoke {
  stroke: var(--ridge);
  stroke-width: 1;
  stroke-dasharray: 4 7;
  opacity: 0.45;
}

.page-about .ridge-line {
  fill: none;
  stroke: var(--ocean);
  stroke-width: 1.6;
  opacity: 0.34;
}

.page-about .node {
  fill: var(--ridge);
  transition: fill 260ms var(--ease), r 260ms var(--ease);
}

.page-about .node--signal {
  fill: var(--signal);
}

/* 纵向时间线主轴 */
.page-about .timeline {
  position: relative;
  padding-block: clamp(14px, 3vw, 26px) clamp(6px, 2vw, 14px);
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 0;
  bottom: 0;
  width: 2px;
  border-radius: 2px;
  background: linear-gradient(180deg, var(--mist) 0%, var(--ridge) 14%, var(--ocean) 50%, var(--ridge) 86%, var(--mist) 100%);
  opacity: 0.55;
}

.page-about .chapter {
  position: relative;
  padding-left: 32px;
  padding-block: clamp(28px, 5vw, 56px);
}

.page-about .chapter::before {
  content: "";
  position: absolute;
  left: 3px;
  top: calc(clamp(28px, 5vw, 56px) + 14px);
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--paper);
  box-shadow: 0 0 0 2px var(--ridge);
  transition: box-shadow 320ms var(--ease), background-color 320ms var(--ease);
}

.page-about .chapter.is-visible::before {
  background: var(--signal);
  box-shadow: 0 0 0 3px var(--signal-soft), 0 0 0 4px var(--signal);
}

.page-about .chapter-no {
  margin: 0 0 10px;
  font-family: var(--ff-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--ridge);
  transition: color 320ms var(--ease);
}

.page-about .chapter.is-visible .chapter-no {
  color: var(--signal);
}

.page-about .chapter h2 {
  margin: 0 0 18px;
  font-family: var(--ff-display);
  font-weight: 900;
  font-size: clamp(25px, 4.3vw, 42px);
  line-height: 1.14;
  letter-spacing: -0.015em;
  color: var(--ocean);
}

.page-about .chapter p {
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.78;
  color: var(--ink);
  max-width: 44em;
}

.page-about .chapter .lede {
  margin: 0 0 20px;
  padding-left: 16px;
  border-left: 3px solid var(--signal-soft);
  font-family: var(--ff-serif);
  font-size: clamp(18px, 2.1vw, 23px);
  line-height: 1.68;
  color: var(--ink);
  max-width: 32em;
}

.page-about .chapter a {
  color: var(--ocean);
  text-decoration: underline;
  text-decoration-color: var(--signal);
  text-decoration-thickness: 2px;
  text-underline-offset: 3px;
}

.page-about .chapter a:hover,
.page-about .chapter a:focus-visible {
  color: var(--signal);
}

/* 五段坐标 */
.page-about .span-list {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 18px;
}

.page-about .span-item {
  padding-top: 16px;
  border-top: 2px solid var(--mist);
  transition: border-color 260ms var(--ease), transform 260ms var(--ease);
}

.page-about .span-item:hover {
  border-color: var(--signal);
  transform: translateY(-3px);
}

.page-about .span-no {
  display: block;
  margin-bottom: 8px;
  font-family: var(--ff-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--data);
}

.page-about .span-item h3 {
  margin: 0 0 8px;
  font-family: var(--ff-display);
  font-size: 19px;
  font-weight: 800;
  line-height: 1.3;
  color: var(--ocean);
}

.page-about .span-item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.72;
  color: var(--ink);
  max-width: 40em;
}

/* 团队 */
.page-about .team-grid {
  display: grid;
  gap: 24px;
  margin: 24px 0 6px;
}

.page-about .ring-wrap {
  position: relative;
  width: 168px;
  height: 168px;
  margin: 0 auto 20px;
}

.page-about .ring {
  display: block;
  width: 100%;
  height: 100%;
}

.page-about .ring-track {
  fill: none;
  stroke: var(--mist);
  stroke-width: 12;
}

.page-about .ring-seg {
  fill: none;
  stroke-width: 12;
  transition: stroke-width 240ms var(--ease);
}

.page-about .ring-seg--data {
  stroke: var(--ocean);
}

.page-about .ring-seg--edit {
  stroke: var(--signal);
}

.page-about .ring-seg--care {
  stroke: var(--data);
}

.page-about .ring-seg:hover {
  stroke-width: 16;
}

.page-about .ring-center {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  pointer-events: none;
}

.page-about .ring-center .num {
  font-family: var(--ff-mono);
  font-variant-numeric: tabular-nums;
  font-size: 27px;
  font-weight: 700;
  line-height: 1;
  color: var(--ocean);
}

.page-about .ring-center .lab {
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--ocean);
  opacity: 0.7;
}

.page-about .ring-legend {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .ring-legend li {
  display: grid;
  grid-template-columns: 12px minmax(0, 1fr) auto;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  line-height: 1.5;
  color: var(--ink);
}

.page-about .ring-legend .mono {
  font-family: var(--ff-mono);
  font-variant-numeric: tabular-nums;
  color: var(--ocean);
  font-weight: 700;
}

.page-about .legend-swatch {
  width: 12px;
  height: 12px;
  border-radius: 3px;
  display: inline-block;
}

.page-about .legend-swatch--data {
  background: var(--ocean);
}

.page-about .legend-swatch--edit {
  background: var(--signal);
}

.page-about .legend-swatch--care {
  background: var(--data);
}

/* 版本时间线 */
.page-about .version-list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .version-item {
  padding: 18px 20px;
  border: 1px solid var(--mist);
  border-radius: var(--r-card);
  background: var(--paper);
  transition: border-color 240ms var(--ease), box-shadow 240ms var(--ease), transform 240ms var(--ease);
}

.page-about .version-item:hover,
.page-about .version-item:focus-visible {
  border-color: var(--signal);
  box-shadow: var(--shadow-lift);
  transform: translateY(-3px);
}

.page-about .version-item:focus-visible {
  outline: 2px solid var(--signal);
  outline-offset: 3px;
}

.page-about .version-tag {
  display: inline-block;
  margin-bottom: 10px;
  padding: 4px 12px;
  border-radius: var(--r-pill);
  background: var(--mist);
  color: var(--ocean);
  font-family: var(--ff-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
}

.page-about .version-item h3 {
  margin: 0;
  font-family: var(--ff-display);
  font-size: 18px;
  font-weight: 800;
  line-height: 1.35;
  color: var(--ocean);
}

.page-about .version-note {
  margin: 0;
  max-height: 0;
  opacity: 0;
  overflow: hidden;
  font-size: 14px;
  line-height: 1.7;
  color: var(--ink);
  transition: max-height 280ms var(--ease), opacity 280ms var(--ease), margin-top 280ms var(--ease);
}

.page-about .version-item:hover .version-note,
.page-about .version-item:focus-visible .version-note {
  max-height: 8em;
  opacity: 1;
  margin-top: 8px;
}

/* 合作生态 */
.page-about .partner-grid {
  display: grid;
  gap: 26px;
  margin-top: 24px;
}

.page-about .partner-copy p {
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.78;
  color: var(--ink);
  max-width: 40em;
}

/* 长期承诺 */
.page-about .promise-list {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
}

.page-about .promise-list li {
  display: flex;
  gap: 16px;
  padding-block: 20px;
  border-bottom: 1px solid var(--mist);
}

.page-about .promise-list li:first-child {
  border-top: 1px solid var(--mist);
}

.page-about .promise-no {
  flex: none;
  padding-top: 4px;
  font-family: var(--ff-mono);
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--signal);
}

.page-about .promise-body h3 {
  margin: 0 0 6px;
  font-family: var(--ff-display);
  font-size: 18px;
  font-weight: 800;
  line-height: 1.35;
  color: var(--ocean);
}

.page-about .promise-body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.74;
  color: var(--ink);
  max-width: 42em;
}

/* 收尾索引 */
.page-about .about-index {
  margin-top: clamp(24px, 4vw, 48px);
  padding-block: clamp(34px, 6vw, 68px) clamp(16px, 3vw, 30px);
  border-top: 1px solid var(--mist);
}

.page-about .about-index h2 {
  margin: 0 0 22px;
  font-family: var(--ff-display);
  font-weight: 900;
  font-size: clamp(22px, 3vw, 30px);
  line-height: 1.2;
  color: var(--ocean);
}

.page-about .index-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 4px;
}

.page-about .index-list a {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 4px 12px;
  padding: 16px 18px;
  border-radius: var(--r-card);
  text-decoration: none;
  color: var(--ink);
  transition: background-color 240ms var(--ease), transform 240ms var(--ease);
}

.page-about .index-list a:hover,
.page-about .index-list a:focus-visible {
  background: var(--mist);
  transform: translateX(4px);
}

.page-about .idx-no {
  grid-row: span 2;
  font-family: var(--ff-mono);
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--signal);
}

.page-about .idx-name {
  font-family: var(--ff-display);
  font-size: 18px;
  font-weight: 800;
  color: var(--ocean);
}

.page-about .idx-desc {
  font-size: 14px;
  line-height: 1.6;
  color: var(--ink);
  opacity: 0.78;
}

@media (max-width: 419px) {
  .page-about .hero-stats {
    grid-template-columns: minmax(0, 1fr);
  }

  .page-about .ring-wrap {
    width: 148px;
    height: 148px;
  }
}

@media (min-width: 760px) {
  .page-about .span-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 22px 26px;
  }
}

@media (min-width: 820px) {
  .page-about .team-grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    align-items: start;
    gap: 34px;
  }

  .page-about .partner-grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    align-items: center;
    gap: 36px;
  }
}

@media (min-width: 900px) {
  .page-about .hero {
    grid-template-columns: minmax(0, 1.02fr) minmax(0, 0.98fr);
    gap: clamp(36px, 5vw, 64px);
  }

  .page-about .timeline::before {
    left: 11px;
  }

  .page-about .chapter {
    padding-left: 60px;
  }

  .page-about .chapter::before {
    left: 7px;
  }
}

@media (hover: none) {
  .page-about .version-note {
    max-height: 8em;
    opacity: 1;
    margin-top: 8px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .chapter::before,
  .page-about .chapter-no,
  .page-about .version-item,
  .page-about .version-note,
  .page-about .span-item,
  .page-about .index-list a,
  .page-about .ring-seg,
  .page-about .node {
    transition: none;
  }

  .page-about .version-item:hover,
  .page-about .span-item:hover,
  .page-about .index-list a:hover {
    transform: none;
  }
}