/* ===== 页面作用域：核定口径与原则 ===== */

.page-about {
  position: relative;
  background: var(--turf);
  color: var(--white);
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  position: relative;
  isolation: isolate;
  padding: calc(var(--header-h) + clamp(44px, 8vw, 104px)) 0 clamp(38px, 5vw, 70px);
  background:
    radial-gradient(110% 80% at 92% -12%, rgba(201, 255, 61, 0.13) 0%, rgba(201, 255, 61, 0) 58%),
    linear-gradient(180deg, var(--ink) 0%, var(--turf) 100%);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background:
    repeating-linear-gradient(118deg, rgba(143, 166, 151, 0.055) 0 1px, transparent 1px 16px),
    radial-gradient(58% 68% at 12% 116%, rgba(94, 216, 255, 0.07) 0%, rgba(94, 216, 255, 0) 72%);
}

.page-about .about-title {
  margin: 14px 0 0;
  max-width: 22ch;
  font-family: var(--font-cond);
  font-weight: 600;
  font-size: clamp(30px, 5.2vw, 60px);
  line-height: 1.12;
  letter-spacing: 0.04em;
}

.page-about .about-lead {
  margin: clamp(18px, 2.4vw, 26px) 0 0;
  max-width: 52ch;
  font-size: clamp(15.5px, 1.5vw, 18px);
  line-height: 1.8;
  color: var(--text-soft);
}

.page-about .about-keyfacts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin-top: clamp(28px, 4vw, 46px);
  background: var(--edge);
  border: 1px solid var(--edge);
}

.page-about .kf {
  padding: 16px 18px 18px;
  background: rgba(6, 10, 8, 0.72);
}

.page-about .kf-num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(24px, 3.2vw, 36px);
  line-height: 1;
  color: var(--acid);
  letter-spacing: 0.02em;
}

.page-about .kf-label {
  display: block;
  margin-top: 9px;
  font-family: var(--font-cond);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--moss);
}

/* ---------- 主体骨架 ---------- */

.page-about .about-shell {
  padding: clamp(40px, 6vw, 84px) 0 clamp(56px, 8vw, 112px);
}

.page-about .about-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 4vw, 48px);
}

/* ---------- 侧边索引 ---------- */

.page-about .about-index {
  padding: 16px 0;
  border-top: 1px solid var(--edge);
  border-bottom: 1px solid var(--edge);
}

.page-about .about-index-title {
  margin: 0 0 14px;
  font-family: var(--font-cond);
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--moss);
}

.page-about .about-index-title-sub {
  margin-top: 22px;
}

.page-about .about-index-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 22px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-index-link {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  font-family: var(--font-cond);
  font-size: 14px;
  letter-spacing: 0.08em;
  color: var(--text-soft);
  text-decoration: none;
  transition: color 0.2s ease;
}

.page-about .about-index-link:hover,
.page-about .about-index-link:focus-visible {
  color: var(--acid);
}

.page-about .about-index-num {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--acid);
}

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

.page-about .about-term-jump a {
  font-size: 13px;
  line-height: 1.6;
  color: var(--moss);
  text-decoration: none;
  border-bottom: 1px solid var(--edge);
  transition: color 0.2s ease, border-color 0.2s ease;
}

.page-about .about-term-jump a:hover,
.page-about .about-term-jump a:focus-visible {
  color: var(--white);
  border-color: var(--acid);
}

/* ---------- 正文栏 ---------- */

.page-about .about-body {
  min-width: 0;
}

.page-about .about-section {
  scroll-margin-top: calc(var(--header-h) + 24px);
}

.page-about .about-section + .about-section {
  margin-top: clamp(46px, 6vw, 88px);
}

.page-about .about-section + .about-section::before {
  content: "";
  display: block;
  height: 10px;
  margin-bottom: clamp(30px, 4vw, 52px);
  background: repeating-linear-gradient(115deg, var(--edge) 0 2px, transparent 2px 11px);
}

.page-about .about-h2 {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin: 0 0 18px;
  font-family: var(--font-cond);
  font-size: clamp(21px, 2.6vw, 32px);
  font-weight: 600;
  line-height: 1.22;
  letter-spacing: 0.06em;
}

.page-about .h2-num {
  font-family: var(--font-mono);
  font-size: clamp(12px, 1.1vw, 14px);
  letter-spacing: 0.12em;
  color: var(--acid);
}

.page-about .about-p {
  margin: 0 0 16px;
  max-width: 44em;
  font-size: clamp(15px, 1.1vw, 16.5px);
  line-height: 1.85;
  color: var(--text-soft);
}

.page-about .about-note {
  margin: 26px 0 0;
  padding-top: 16px;
  border-top: 1px dashed var(--edge);
  max-width: 46em;
  font-size: 13px;
  line-height: 1.8;
  color: var(--moss);
}

/* ---------- 三层口径阶梯 ---------- */

.page-about .ladder {
  display: grid;
  gap: 12px;
  margin: clamp(24px, 3vw, 34px) 0 0;
}

.page-about .ladder-step {
  position: relative;
  padding: clamp(18px, 2.6vw, 28px) clamp(18px, 2.6vw, 30px) clamp(18px, 2.6vw, 28px) clamp(54px, 6vw, 76px);
  border: 1px solid var(--edge);
  background: linear-gradient(120deg, rgba(20, 48, 37, 0.95) 0%, rgba(11, 18, 14, 0.9) 100%);
  animation: about-step-in 0.55s cubic-bezier(0.22, 0.72, 0.3, 1) both;
}

.page-about .ladder-step:nth-child(2) {
  margin-left: 3%;
  animation-delay: 0.1s;
}

.page-about .ladder-step:nth-child(3) {
  margin-left: 6%;
  animation-delay: 0.2s;
}

.page-about .ladder-step::after {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 3px;
  background: var(--acid);
  opacity: 0.85;
}

.page-about .ladder-num {
  position: absolute;
  left: clamp(16px, 2.4vw, 26px);
  top: clamp(18px, 2.6vw, 30px);
  font-family: var(--font-mono);
  font-size: 18px;
  letter-spacing: 0.05em;
  color: var(--acid);
}

.page-about .ladder-title {
  margin: 0 0 8px;
  font-family: var(--font-cond);
  font-size: clamp(17px, 1.6vw, 21px);
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--white);
}

.page-about .ladder-text {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-soft);
}

@keyframes about-step-in {
  from {
    opacity: 0;
    transform: translateY(14px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

/* ---------- 样本边界网格 ---------- */

.page-about .boundary-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  margin-top: clamp(22px, 3vw, 32px);
}

.page-about .boundary-item {
  padding: 18px 20px 20px;
  border: 1px solid var(--edge);
  background:
    repeating-linear-gradient(135deg, rgba(201, 255, 61, 0.04) 0 6px, transparent 6px 15px),
    rgba(11, 18, 14, 0.72);
}

.page-about .boundary-k {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(20px, 2.4vw, 28px);
  line-height: 1.1;
  color: var(--acid);
  letter-spacing: 0.02em;
}

.page-about .boundary-v {
  margin: 10px 0 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--text-soft);
}

/* ---------- 核定流程 ---------- */

.page-about .flow {
  counter-reset: flowstep;
  display: grid;
  gap: 12px;
  margin: clamp(22px, 3vw, 32px) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .flow-item {
  position: relative;
  padding: 18px 20px 18px 62px;
  border-left: 2px solid var(--edge);
  background: rgba(20, 48, 37, 0.5);
}

.page-about .flow-item::before {
  counter-increment: flowstep;
  content: "0" counter(flowstep);
  position: absolute;
  left: 20px;
  top: 18px;
  font-family: var(--font-mono);
  font-size: 15px;
  letter-spacing: 0.06em;
  color: var(--acid);
}

.page-about .flow-title {
  margin: 0 0 6px;
  font-family: var(--font-cond);
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 0.09em;
  color: var(--white);
}

.page-about .flow-text {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--text-soft);
}

/* ---------- 术语表 ---------- */

.page-about .term-list {
  margin: clamp(22px, 3vw, 32px) 0 0;
  padding: 0;
}

.page-about .term-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 6px;
  padding: 20px 0;
  border-top: 1px solid var(--edge);
  scroll-margin-top: calc(var(--header-h) + 26px);
  transition: background-color 0.25s ease;
}

.page-about .term-row:last-child {
  border-bottom: 1px solid var(--edge);
}

.page-about .term-row:target {
  background: rgba(201, 255, 61, 0.07);
  box-shadow: inset 3px 0 0 var(--acid);
}

.page-about .term-name {
  font-family: var(--font-mono);
  font-size: clamp(16px, 1.5vw, 19px);
  letter-spacing: 0.18em;
  color: var(--white);
}

.page-about .term-row:target .term-name {
  color: var(--acid);
}

.page-about .term-desc {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-soft);
}

/* ---------- 图像容器 ---------- */

.page-about .about-figure {
  margin: clamp(26px, 3.5vw, 42px) 0 0;
}

.page-about .about-media {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--edge);
  background: var(--ink);
}

.page-about .about-media[data-ratio="16-9"] {
  aspect-ratio: 16 / 9;
}

.page-about .about-media[data-ratio="3-2"] {
  aspect-ratio: 3 / 2;
}

.page-about .about-media[data-ratio="1-1"] {
  aspect-ratio: 1 / 1;
  max-width: 560px;
}

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

.page-about .media-caption {
  margin-top: 10px;
  max-width: 46em;
  font-size: 12.5px;
  line-height: 1.7;
  letter-spacing: 0.06em;
  color: var(--moss);
}

/* ---------- 折叠组 ---------- */

.page-about .fold {
  margin: clamp(22px, 3vw, 30px) 0 0;
  border: 1px solid var(--edge);
  background: rgba(20, 48, 37, 0.42);
}

.page-about .fold-summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 16px 20px;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-cond);
  font-size: 16px;
  letter-spacing: 0.09em;
  color: var(--white);
}

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

.page-about .fold-summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 18px;
  color: var(--acid);
}

.page-about .fold[open] .fold-summary::after {
  content: "–";
}

.page-about .fold-summary:focus-visible {
  outline: 2px solid var(--acid);
  outline-offset: 2px;
}

.page-about .fold-body {
  padding: 0 20px 20px;
}

.page-about .mini-flow {
  margin: 0;
  padding-left: 20px;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--text-soft);
}

.page-about .mini-flow li + li {
  margin-top: 8px;
}

.page-about .mini-flow strong {
  color: var(--white);
  font-weight: 600;
}

/* ---------- 提交通道 ---------- */

.page-about .about-contact {
  margin: clamp(24px, 3.5vw, 36px) 0 0;
  padding: clamp(20px, 2.8vw, 28px);
  border: 1px solid var(--edge);
  border-left: 3px solid var(--acid);
  background: linear-gradient(135deg, rgba(20, 48, 37, 0.75) 0%, rgba(11, 18, 14, 0.85) 100%);
}

.page-about .about-contact-title {
  margin: 0 0 14px;
  font-family: var(--font-cond);
  font-size: 13px;
  letter-spacing: 0.18em;
  color: var(--moss);
}

.page-about .about-contact-item {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.7;
  color: var(--white);
  overflow-wrap: anywhere;
}

.page-about .about-contact-note {
  margin: 14px 0 20px;
  max-width: 46em;
  font-size: 13px;
  line-height: 1.8;
  color: var(--text-soft);
}

/* ---------- 响应式 ---------- */

@media (min-width: 700px) {
  .page-about .about-keyfacts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .page-about .term-row {
    grid-template-columns: minmax(120px, 176px) minmax(0, 1fr);
    gap: clamp(18px, 3vw, 40px);
    align-items: baseline;
  }
}

@media (min-width: 1000px) {
  .page-about .about-grid {
    grid-template-columns: minmax(190px, 240px) minmax(0, 1fr);
    align-items: start;
    gap: clamp(40px, 5vw, 84px);
  }

  .page-about .about-index {
    padding: 0 0 0 18px;
    border-top: 0;
    border-bottom: 0;
    border-left: 2px solid var(--edge);
  }

  .page-about .about-index-inner {
    position: sticky;
    top: calc(var(--header-h) + 28px);
  }

  .page-about .about-index-list {
    display: block;
  }

  .page-about .about-index-list > li + li {
    margin-top: 12px;
  }

  .page-about .about-index-link {
    display: flex;
  }
}

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

  .page-about .about-index-link,
  .page-about .about-term-jump a,
  .page-about .term-row {
    transition: none;
  }
}