.page-about {
  --about-index-stroke: rgba(255, 90, 54, .6);
  --about-grid-line: rgba(0, 255, 136, .06);
  --about-paper-index: rgba(20, 20, 20, .14);
  background: var(--c-deep);
  color: var(--c-paper);
  font-family: var(--font-body);
  overflow-x: hidden;
}

/* ===== 英雄区 ===== */
.page-about .about-hero {
  position: relative;
  padding: clamp(48px, 8vw, 96px) 0 clamp(56px, 9vw, 120px);
  background: linear-gradient(180deg, var(--c-deep-3) 0%, var(--c-deep) 100%);
  border-bottom: 3px solid var(--c-orange);
  overflow: hidden;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--c-green) 1px, transparent 1px),
    linear-gradient(90deg, var(--c-green) 1px, transparent 1px);
  background-size: 80px 80px;
  opacity: .06;
  pointer-events: none;
}

.page-about .about-hero::after {
  content: "BY/2025";
  position: absolute;
  right: -2vw;
  bottom: -6vw;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(100px, 16vw, 260px);
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1px rgba(242, 232, 208, .1);
  pointer-events: none;
  z-index: 0;
}

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

.page-about .about-hero-grid {
  display: grid;
  gap: clamp(40px, 6vw, 80px);
  margin-top: clamp(48px, 7vw, 88px);
}

.page-about .about-hero-title {
  font-family: var(--font-headline);
  font-weight: 900;
  font-size: clamp(38px, 6vw, 76px);
  line-height: 1.02;
  letter-spacing: -0.03em;
  margin: 0 0 20px;
  color: var(--c-paper);
  max-width: 680px;
}

.page-about .about-hero-sub {
  font-size: clamp(16px, 1.4vw, 19px);
  line-height: 1.7;
  color: rgba(242, 232, 208, .72);
  max-width: 600px;
  margin: 0;
}

.page-about .about-hero-aside {
  border-left: 3px solid var(--c-orange);
  padding-left: clamp(20px, 3vw, 32px);
}

.page-about .about-hero-aside-label {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--c-green);
  margin: 0 0 16px;
}

.page-about .about-chapter-list {
  display: grid;
  gap: 0;
}

.page-about .about-chapter-link {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 8px;
  border-bottom: 1px solid rgba(242, 232, 208, .12);
  text-decoration: none;
  color: var(--c-paper);
  transition: background var(--t-fast), color var(--t-fast), padding-left var(--t-fast);
}

.page-about .about-chapter-link:first-child {
  border-top: 1px solid rgba(242, 232, 208, .12);
}

.page-about .about-chapter-link:hover,
.page-about .about-chapter-link:focus-visible {
  background: rgba(255, 90, 54, .12);
  padding-left: 16px;
}

.page-about .about-chapter-link-index {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  color: var(--c-orange);
  min-width: 30px;
}

.page-about .about-chapter-link-title {
  font-size: 16px;
  font-weight: 600;
  flex: 1;
}

.page-about .about-chapter-link-arrow {
  font-size: 18px;
  color: rgba(242, 232, 208, .4);
  transition: color var(--t-fast), transform var(--t-fast);
}

.page-about .about-chapter-link:hover .about-chapter-link-arrow,
.page-about .about-chapter-link:focus-visible .about-chapter-link-arrow {
  color: var(--c-green);
  transform: translate(2px, -2px);
}

/* ===== 章节通用 ===== */
.page-about .about-century {
  position: relative;
  padding: clamp(72px, 10vw, 128px) 0;
}

.page-about .about-century--paper {
  background: var(--c-paper);
  color: var(--c-ink);
}

.page-about .about-century--deep {
  background: var(--c-deep);
  color: var(--c-paper);
}

.page-about .about-century--deep::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--c-green) 1px, transparent 1px),
    linear-gradient(90deg, var(--c-green) 1px, transparent 1px);
  background-size: 70px 70px;
  opacity: .04;
  pointer-events: none;
}

.page-about .about-century>* {
  position: relative;
  z-index: 1;
}

.page-about .about-century-head {
  display: flex;
  align-items: flex-end;
  gap: clamp(24px, 4vw, 56px);
  margin-bottom: clamp(40px, 6vw, 80px);
  border-bottom: 2px solid rgba(20, 20, 20, .14);
  padding-bottom: clamp(16px, 3vw, 32px);
}

.page-about .about-century-head--light {
  border-bottom-color: rgba(242, 232, 208, .16);
}

.page-about .about-century-index {
  font-family: var(--font-headline);
  font-weight: 900;
  font-size: clamp(64px, 9vw, 128px);
  line-height: .82;
  letter-spacing: -0.05em;
  color: transparent;
  -webkit-text-stroke: 2px var(--about-index-stroke);
  flex-shrink: 0;
}

.page-about .about-century--paper .about-century-index {
  -webkit-text-stroke: 2px var(--about-paper-index);
}

.page-about .about-century-head-copy {
  padding-bottom: 4px;
}

.page-about .about-century-eyebrow {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--c-orange);
  margin: 0 0 8px;
}

.page-about .about-century--paper .about-century-eyebrow {
  color: #c94a2b;
}

.page-about .about-century-title {
  font-family: var(--font-headline);
  font-weight: 800;
  font-size: clamp(32px, 4.5vw, 56px);
  line-height: 1.08;
  letter-spacing: -0.02em;
  margin: 0;
}

/* ===== 01 我们为何而生 ===== */
.page-about .about-origin-grid {
  display: grid;
  gap: clamp(36px, 6vw, 80px);
}

@media (min-width: 1024px) {
  .page-about .about-origin-grid {
    grid-template-columns: 1.15fr .85fr;
    gap: clamp(48px, 7vw, 100px);
    align-items: center;
  }
}

.page-about .about-origin-text>* {
  margin-top: 0;
}

.page-about .about-origin-text p {
  font-size: clamp(16px, 1.3vw, 18px);
  line-height: 1.75;
  color: rgba(20, 20, 20, .78);
  margin: 0 0 20px;
}

.page-about .about-origin-text .btn {
  margin-top: 12px;
}

.page-about .about-origin-stats {
  display: grid;
  gap: 20px;
}

@media (min-width: 640px) {
  .page-about .about-origin-stats {
    grid-template-columns: repeat(2, 1fr);
    gap: 22px;
  }

  .page-about .about-stat-card:first-child {
    grid-column: 1 / -1;
  }
}

.page-about .about-stat-card {
  background: var(--c-deep);
  border: 2px solid var(--c-deep-3);
  border-radius: 0;
  box-shadow: 8px 8px 0 rgba(20, 20, 20, .28);
  color: var(--c-paper);
  padding: 26px 24px;
  position: relative;
  min-height: 140px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  transition: transform var(--t-fast), box-shadow var(--t-fast);
}

.page-about .about-stat-card:hover {
  transform: translate(-3px, -3px);
  box-shadow: 12px 12px 0 rgba(20, 20, 20, .2);
}

.page-about .about-stat-card .status-dot {
  position: absolute;
  top: 16px;
  right: 16px;
}

.page-about .about-stat-card .data-label {
  font-size: 13px;
  letter-spacing: .06em;
  color: rgba(242, 232, 208, .68);
  margin: 0 0 4px;
}

.page-about .about-stat-card .data-number {
  font-family: var(--font-mono);
  font-size: clamp(48px, 5vw, 64px);
  font-weight: 700;
  line-height: 1;
  color: var(--c-green);
  margin: 0;
}

.page-about .about-stat-card .data-number span {
  font-size: .4em;
  margin-left: 4px;
  color: rgba(242, 232, 208, .72);
  font-weight: 500;
}

/* ===== 02 数据体系一览 ===== */
.page-about .about-system-grid {
  display: grid;
  gap: clamp(36px, 6vw, 80px);
}

@media (min-width: 1024px) {
  .page-about .about-system-grid {
    grid-template-columns: 1.05fr .95fr;
    gap: clamp(48px, 7vw, 88px);
    align-items: center;
  }
}

.page-about .about-system-img {
  background: var(--c-deep-2);
  border: 2px solid rgba(0, 255, 136, .2);
  box-shadow: 12px 12px 0 rgba(0, 0, 0, .3);
}

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

.page-about .about-system-lead {
  font-size: clamp(17px, 1.4vw, 20px);
  line-height: 1.7;
  color: rgba(242, 232, 208, .82);
  margin: 0 0 28px;
}

.page-about .about-system-list {
  list-style: none;
  margin: 0 0 36px;
  padding: 0;
}

.page-about .about-system-list li {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 14px 0;
  border-bottom: 1px dashed rgba(242, 232, 208, .18);
  font-size: 15px;
  line-height: 1.6;
  color: rgba(242, 232, 208, .82);
}

.page-about .about-system-list li:first-child {
  border-top: 1px dashed rgba(242, 232, 208, .18);
}

.page-about .about-system-list .tag {
  flex-shrink: 0;
  min-width: 76px;
  text-align: center;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  padding: 4px 10px;
  border: 1px solid rgba(0, 255, 136, .45);
  color: var(--c-green);
  background: rgba(0, 255, 136, .06);
  letter-spacing: .04em;
  white-space: nowrap;
}

.page-about .about-system-metrics {
  display: flex;
  flex-wrap: wrap;
  gap: clamp(28px, 4vw, 56px);
  padding-top: 8px;
}

.page-about .about-metric {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.page-about .about-metric .data-number {
  font-family: var(--font-mono);
  font-size: clamp(40px, 4.6vw, 58px);
  font-weight: 700;
  line-height: 1;
  color: var(--c-green);
  margin: 0;
}

.page-about .about-metric .data-label {
  font-size: 13px;
  color: rgba(242, 232, 208, .6);
  margin: 0;
  letter-spacing: .04em;
}

/* ===== 03 认证与合作 ===== */
.page-about .about-trust-grid {
  display: grid;
  gap: 36px;
}

.page-about .about-trust-grid .about-trust-detail {
  order: -1;
}

.page-about .about-trust-lead {
  font-size: clamp(17px, 1.4vw, 20px);
  font-weight: 600;
  line-height: 1.7;
  color: var(--c-ink);
  margin: 0 0 30px;
}

.page-about .about-trust-list {
  list-style: none;
  margin: 0 0 28px;
  padding: 0;
}

.page-about .about-trust-list li {
  display: flex;
  align-items: flex-start;
  gap: 18px;
  padding: 20px 0;
  border-bottom: 2px solid rgba(20, 20, 20, .1);
}

.page-about .about-trust-list li:first-child {
  border-top: 2px solid rgba(20, 20, 20, .1);
}

.page-about .about-trust-list .status-dot {
  margin-top: 6px;
  flex-shrink: 0;
}

.page-about .about-trust-list strong {
  display: block;
  font-family: var(--font-headline);
  font-size: 19px;
  font-weight: 800;
  margin-bottom: 6px;
  color: var(--c-ink);
}

.page-about .about-trust-list p {
  font-size: 15px;
  line-height: 1.65;
  color: rgba(20, 20, 20, .68);
  margin: 0;
}

.page-about .about-trust-note {
  font-size: 14px;
  line-height: 1.7;
  color: rgba(20, 20, 20, .55);
  border-left: 3px solid var(--c-orange);
  padding-left: 16px;
  margin: 0;
}

.page-about .about-trust-media {
  display: flex;
  align-items: center;
  justify-content: center;
}

.page-about .about-trust-img {
  width: 100%;
  max-width: 420px;
  background: var(--c-deep);
  border: 2px solid rgba(20, 20, 20, .2);
  box-shadow: 10px 10px 0 rgba(20, 20, 20, .18);
}

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

@media (min-width: 1024px) {
  .page-about .about-trust-grid {
    grid-template-columns: .82fr 1.18fr;
    gap: clamp(48px, 7vw, 96px);
    align-items: center;
  }

  .page-about .about-trust-grid .about-trust-detail {
    order: 2;
  }

  .page-about .about-trust-grid .about-trust-media {
    order: 1;
  }
}

/* ===== 04 发展里程碑 ===== */
.page-about .about-milestone-wrap {
  max-width: 760px;
}

.page-about .about-timeline {
  list-style: none;
  margin: 0 0 clamp(44px, 6vw, 72px);
  padding: 0;
  position: relative;
}

.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 9px;
  top: 10px;
  bottom: 10px;
  width: 2px;
  background: linear-gradient(180deg, var(--c-green) 0%, rgba(0, 255, 136, .28) 40%, rgba(255, 90, 54, .5) 100%);
}

.page-about .about-timeline-item {
  position: relative;
  padding: 0 0 clamp(40px, 5vw, 64px) clamp(40px, 6vw, 72px);
}

.page-about .about-timeline-item:last-child {
  padding-bottom: 0;
}

.page-about .about-timeline-item::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: clamp(40px, 6vw, 72px);
  height: 2px;
  background: repeating-linear-gradient(
    -45deg,
    var(--c-orange) 0 8px,
    transparent 8px 16px
  );
}

.page-about .about-timeline-item:not(:last-child)::after {
  display: block;
}

.page-about .about-timeline-item:last-child::after {
  display: none;
}

.page-about .about-timeline-dot {
  position: absolute;
  left: 0;
  top: 8px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--c-green);
  border: 3px solid var(--c-deep);
  box-shadow: 0 0 0 4px rgba(0, 255, 136, .22);
  z-index: 1;
}

.page-about .about-timeline-body {
  background: rgba(255, 255, 255, .03);
  border: 1px solid rgba(242, 232, 208, .1);
  padding: clamp(22px, 3vw, 32px);
  transition: border-color var(--t-fast), background var(--t-fast);
}

.page-about .about-timeline-body:hover {
  border-color: rgba(0, 255, 136, .3);
  background: rgba(255, 255, 255, .05);
}

.page-about .about-timeline-year {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: clamp(28px, 3.4vw, 42px);
  font-weight: 700;
  line-height: 1;
  color: var(--c-orange);
  margin-bottom: 14px;
  padding-bottom: 8px;
  border-bottom: 2px solid rgba(0, 255, 136, .5);
}

.page-about .about-timeline-body h3 {
  font-family: var(--font-headline);
  font-size: clamp(18px, 2vw, 24px);
  font-weight: 800;
  margin: 0 0 10px;
  color: var(--c-paper);
}

.page-about .about-timeline-body p {
  font-size: 15px;
  line-height: 1.7;
  color: rgba(242, 232, 208, .68);
  margin: 0;
}

.page-about .about-milestone-img {
  background: var(--c-deep-2);
  border: 2px solid rgba(0, 255, 136, .2);
  box-shadow: 12px 12px 0 rgba(0, 0, 0, .3);
  margin-top: clamp(12px, 2vw, 24px);
}

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

.page-about .about-milestone-caption {
  font-size: 14px;
  color: rgba(242, 232, 208, .55);
  text-align: right;
  margin: 14px 0 0;
  letter-spacing: .03em;
}

/* ===== 收尾引导 ===== */
.page-about .about-closing {
  position: relative;
  padding: clamp(72px, 10vw, 128px) 0;
  background: var(--c-ink);
  color: var(--c-paper);
  text-align: center;
  overflow: hidden;
}

.page-about .about-closing::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 12px;
  background: repeating-linear-gradient(
    -45deg,
    var(--c-orange) 0 14px,
    var(--c-green) 14px 28px
  );
}

.page-about .about-closing::after {
  content: "BY/2025";
  position: absolute;
  left: 50%;
  bottom: -4vw;
  transform: translateX(-50%);
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(90px, 14vw, 200px);
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1px rgba(242, 232, 208, .07);
  pointer-events: none;
}

.page-about .about-closing .container {
  position: relative;
  z-index: 1;
}

.page-about .about-closing-eyebrow {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--c-green);
  margin: 0 0 16px;
}

.page-about .about-closing-title {
  font-family: var(--font-headline);
  font-weight: 900;
  font-size: clamp(28px, 4vw, 52px);
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin: 0 auto 32px;
  max-width: 620px;
}

.page-about .about-closing-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 14px;
  margin-bottom: 32px;
}

.page-about .about-closing-btn {
  min-width: 180px;
  justify-content: center;
}

.page-about .about-closing .btn-ghost {
  border-color: rgba(242, 232, 208, .45);
  color: var(--c-paper);
}

.page-about .about-closing .btn-ghost:hover,
.page-about .about-closing .btn-ghost:focus-visible {
  border-color: var(--c-green);
  color: var(--c-green);
}

.page-about .about-closing-trust {
  font-size: 14px;
  line-height: 1.7;
  color: rgba(242, 232, 208, .62);
  max-width: 640px;
  margin: 0 auto 28px;
}

.page-about .about-closing-home a {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--c-orange);
  text-decoration: none;
  border-bottom: 1px solid rgba(255, 90, 54, .4);
  padding-bottom: 3px;
  transition: color var(--t-fast), border-color var(--t-fast);
}

.page-about .about-closing-home a:hover,
.page-about .about-closing-home a:focus-visible {
  color: var(--c-green);
  border-color: var(--c-green);
}

/* ===== 桌面细节修正 ===== */
@media (min-width: 768px) {
  .page-about .about-hero-grid {
    grid-template-columns: 1.15fr .85fr;
    align-items: end;
  }

  .page-about .about-century-pad-lg {
    padding-left: 8%;
  }
}

@media (prefers-reduced-motion: no-preference) {
  .page-about .about-stat-card,
  .page-about .about-timeline-body,
  .page-about .about-chapter-link {
    transition: transform var(--t-fast), box-shadow var(--t-fast), background var(--t-fast), color var(--t-fast), padding-left var(--t-fast), border-color var(--t-fast);
  }
}