.page-about {
  --about-sticky: 96px;
  --about-rule: rgba(36, 26, 20, 0.22);
  background: var(--ink);
  color: var(--warm);
  overflow-x: hidden;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding: clamp(26px, 4.6vw, 48px) 0 clamp(46px, 7vw, 92px);
  border-bottom: 6px solid var(--line);
  overflow: hidden;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: min(48%, 540px);
  height: 100%;
  background-image:
    repeating-linear-gradient(90deg, rgba(51, 224, 208, 0.16) 0 1px, transparent 1px 30px),
    repeating-linear-gradient(0deg, rgba(51, 224, 208, 0.09) 0 1px, transparent 1px 30px);
  mask-image: linear-gradient(to left, #000 20%, transparent 100%);
  -webkit-mask-image: linear-gradient(to left, #000 20%, transparent 100%);
  pointer-events: none;
}

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

.page-about .about-crumbs {
  margin-bottom: clamp(28px, 4vw, 44px);
}

.page-about .crumb-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
}

.page-about .crumb-list li + li::before {
  content: "/";
  margin-right: 10px;
  color: var(--line);
}

.page-about .crumb-link {
  color: var(--steel);
  text-decoration: none;
}

.page-about .crumb-link:hover {
  color: var(--cyan);
}

.page-about .crumb-current {
  color: var(--orange);
}

.page-about .about-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 22px;
  padding: 7px 14px;
  border: 1px solid var(--line);
  background: rgba(18, 44, 66, 0.7);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--warm);
}

.page-about .about-pulse {
  width: 8px;
  height: 8px;
  background: var(--cyan);
  box-shadow: 0 0 0 3px rgba(51, 224, 208, 0.18);
  animation: about-pulse 2.4s ease-in-out infinite;
}

@keyframes about-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.35; }
}

.page-about .about-title {
  margin: 0 0 26px;
  font-family: var(--font-sans);
  font-weight: 800;
  font-size: clamp(2rem, 6.6vw, 4.4rem);
  line-height: 1.1;
  letter-spacing: -0.01em;
  color: var(--warm);
  max-width: 20ch;
}

.page-about .about-title span {
  display: block;
  color: var(--cyan);
}

.page-about .about-lede {
  max-width: 62ch;
  margin: 0 0 34px;
  font-size: clamp(1rem, 2.1vw, 1.125rem);
  line-height: 1.85;
  color: var(--steel);
}

.page-about .about-facts {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 30px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--steel);
}

.page-about .about-facts li {
  position: relative;
  padding-left: 38px;
  line-height: 1.9;
}

.page-about .about-facts li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  width: 26px;
  height: 3px;
  background: var(--orange);
  transform: translateY(-50%);
}

/* ---------- 奶油纸阅读区 ---------- */
.page-about .about-body {
  background: var(--paper);
  color: var(--brown);
}

.page-about .about-body .wrap {
  padding-top: clamp(30px, 4.5vw, 52px);
  padding-bottom: clamp(30px, 4.5vw, 52px);
}

.page-about .about-chapter {
  position: relative;
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(18px, 2.6vw, 30px);
  padding: clamp(34px, 5.5vw, 68px) 0;
}

.page-about .about-chapter + .about-chapter::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background-image: repeating-linear-gradient(90deg, var(--brown) 0 14px, transparent 14px 28px);
  opacity: 0.5;
}

.page-about .about-chapter-num {
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.page-about .about-chapter-num span {
  font-family: var(--font-mono);
  font-size: clamp(2.4rem, 7vw, 3.6rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--brown);
}

.page-about .about-chapter-num em {
  font-style: normal;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.22em;
  color: var(--teal);
  padding-top: 4px;
  border-top: 2px solid var(--orange);
}

.page-about .about-chapter-body h2 {
  margin: 0 0 18px;
  font-size: clamp(1.35rem, 3.4vw, 2rem);
  font-weight: 800;
  line-height: 1.35;
  color: var(--brown);
  max-width: 24ch;
}

.page-about .about-chapter-body p {
  margin: 0 0 16px;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--brown);
  max-width: 66ch;
}

.page-about .about-chapter-body .about-lead-text {
  font-size: clamp(1rem, 2.2vw, 1.1rem);
  font-weight: 500;
  color: #3a2b20;
  padding-left: 16px;
  border-left: 4px solid var(--orange);
}

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

.page-about .about-chapter-body a:hover {
  color: var(--orange);
}

.page-about .about-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 22px;
}

.page-about .about-tags .tag {
  border: 1px solid var(--brown);
  color: var(--brown);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  padding: 5px 10px;
  background: transparent;
}

/* ---------- 认证识别 ---------- */
.page-about .cert-table-wrap {
  margin: 26px 0 0;
  overflow-x: auto;
  border: 2px solid var(--brown);
  box-shadow: 6px 6px 0 rgba(36, 26, 20, 0.18);
}

.page-about .cert-table {
  width: 100%;
  min-width: 540px;
  border-collapse: collapse;
  background: var(--warm);
  font-size: 0.95rem;
}

.page-about .cert-table th,
.page-about .cert-table td {
  padding: 14px 16px;
  text-align: left;
  vertical-align: top;
  line-height: 1.7;
}

.page-about .cert-table thead th {
  background: var(--brown);
  color: var(--warm);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.1em;
}

.page-about .cert-table tbody th {
  width: 26%;
  font-weight: 700;
  color: var(--brown);
  border-top: 1px solid var(--about-rule);
}

.page-about .cert-table tbody td {
  border-top: 1px solid var(--about-rule);
  color: #3a2b20;
}

.page-about .about-cert-figure {
  margin: 30px 0 0;
}

.page-about .about-cert-media {
  border: 2px solid var(--brown);
  background: var(--ink);
  max-width: 420px;
}

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

.page-about .figure-caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: #5c4a3c;
}

.page-about .cert-details {
  margin-top: 24px;
  border: 2px solid var(--brown);
  background: var(--warm);
}

.page-about .cert-details summary {
  cursor: pointer;
  padding: 16px 18px;
  font-weight: 700;
  font-size: 1rem;
  color: var(--brown);
  list-style: none;
  display: flex;
  align-items: center;
  gap: 12px;
}

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

.page-about .cert-details summary::before {
  content: "＋";
  font-family: var(--font-mono);
  color: var(--orange);
  font-size: 1.1rem;
  line-height: 1;
}

.page-about .cert-details[open] summary::before {
  content: "－";
}

.page-about .cert-steps {
  margin: 0;
  padding: 0 22px 20px 44px;
  color: #3a2b20;
}

.page-about .cert-steps li {
  margin-bottom: 10px;
  line-height: 1.8;
}

.page-about .cert-steps li:last-child {
  margin-bottom: 0;
}

/* ---------- 版本演进阶梯 ---------- */
.page-about .stage-list {
  margin: 28px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 14px;
}

.page-about .stage-item {
  position: relative;
  border: 2px solid var(--brown);
  background: var(--warm);
  padding: 18px 20px 18px 24px;
  box-shadow: 5px 5px 0 rgba(36, 26, 20, 0.16);
  transition: transform 200ms var(--ease), box-shadow 200ms var(--ease);
}

.page-about .stage-item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 6px;
  background: var(--teal);
}

.page-about .stage-item:hover {
  transform: translateY(-2px);
  box-shadow: 7px 7px 0 rgba(36, 26, 20, 0.2);
}

.page-about .stage-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--orange);
  margin-bottom: 6px;
}

.page-about .stage-title {
  margin: 0 0 8px;
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--brown);
}

.page-about .stage-desc {
  margin: 0;
  font-size: 0.95rem;
  line-height: 1.8;
  color: #3a2b20;
}

.page-about .stage-hint {
  display: block;
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px dashed var(--about-rule);
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.7;
  letter-spacing: 0.03em;
  color: var(--teal);
}

.page-about .about-stage-figure {
  margin: 30px 0 0;
}

.page-about .about-stage-media {
  border: 2px solid var(--brown);
  background: var(--ink);
  overflow: hidden;
}

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

.page-about .about-inline-link {
  margin-top: 22px;
  font-size: 0.95rem;
}

/* ---------- 团队数据 ---------- */
.page-about .metric-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 26px 0 24px;
  background: var(--brown);
  border: 2px solid var(--brown);
}

.page-about .metric-cell {
  background: var(--warm);
  padding: 18px 16px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.page-about .metric-num {
  font-family: var(--font-mono);
  font-size: clamp(1.6rem, 4.6vw, 2.2rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--brown);
}

.page-about .metric-label {
  font-size: 0.82rem;
  line-height: 1.6;
  color: #5c4a3c;
}

.page-about .about-team-figure {
  margin: 26px 0 0;
}

.page-about .about-team-media {
  border: 2px solid var(--brown);
  background: var(--ink);
  overflow: hidden;
}

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

/* ---------- 回访数据 ---------- */
.page-about .return-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
  margin: 26px 0 24px;
}

.page-about .return-item {
  border-left: 6px solid var(--orange);
  background: rgba(255, 248, 236, 0.72);
  padding: 14px 18px;
}

.page-about .return-num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 4.4vw, 2rem);
  font-weight: 700;
  line-height: 1.1;
  color: var(--brown);
  margin-bottom: 6px;
}

.page-about .return-text {
  margin: 0;
  font-size: 0.92rem;
  line-height: 1.75;
  color: #3a2b20;
  max-width: none;
}

/* ---------- 尾部行动 ---------- */
.page-about .about-cta {
  background: var(--ink);
  border-top: 6px solid var(--line);
  padding: clamp(40px, 6vw, 76px) 0;
}

.page-about .about-cta-kicker {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.22em;
  color: var(--orange);
}

.page-about .about-cta h2 {
  margin: 0 0 16px;
  font-size: clamp(1.4rem, 3.8vw, 2.1rem);
  font-weight: 800;
  line-height: 1.35;
  color: var(--warm);
  max-width: 22ch;
}

.page-about .about-cta-text {
  margin: 0 0 30px;
  max-width: 58ch;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--steel);
}

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

.page-about .about-cta-btns .btn {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
}

.page-about .about-cta-btns .btn:focus-visible {
  outline: none;
  box-shadow: var(--focus);
}

/* ---------- 响应式 ---------- */
@media (min-width: 860px) {
  .page-about .about-chapter {
    grid-template-columns: 150px minmax(0, 1fr);
    gap: clamp(30px, 5vw, 64px);
  }

  .page-about .about-chapter-num {
    position: sticky;
    top: var(--about-sticky);
    align-self: start;
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
  }

  .page-about .stage-list {
    gap: 18px;
  }

  .page-about .stage-item:nth-child(2) {
    margin-left: 32px;
  }

  .page-about .stage-item:nth-child(3) {
    margin-left: 64px;
  }

  .page-about .stage-hint {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    margin-top: 0;
    padding-top: 0;
    border-top-color: transparent;
    transition: max-height 220ms var(--ease), opacity 220ms var(--ease),
      margin-top 220ms var(--ease), padding-top 220ms var(--ease);
  }

  .page-about .stage-item:hover .stage-hint,
  .page-about .stage-item:focus-within .stage-hint {
    max-height: 140px;
    opacity: 1;
    margin-top: 10px;
    padding-top: 10px;
    border-top-color: var(--about-rule);
  }

  .page-about .metric-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .return-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px;
  }
}

@media (min-width: 1180px) {
  .page-about .about-title {
    max-width: 22ch;
  }

  .page-about .about-cert-media {
    max-width: 460px;
  }
}

@media (max-width: 480px) {
  .page-about .about-facts li {
    padding-left: 30px;
  }

  .page-about .about-facts li::before {
    width: 18px;
  }

  .page-about .about-cta-btns .btn {
    width: 100%;
    text-align: center;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-pulse {
    animation: none;
  }

  .page-about .stage-item,
  .page-about .stage-hint {
    transition: none;
  }
}