.page-about {
  --about-ink-soft: rgba(31, 31, 31, 0.72);
  background-color: var(--color-bg);
  overflow-x: hidden;
}

/* ===== 首屏框景 ===== */
.page-about__hero {
  position: relative;
  padding: calc(var(--header-height) + 40px) 16px 56px;
  background:
    radial-gradient(circle at 85% 15%, rgba(194, 155, 98, 0.22) 0%, transparent 46%),
    linear-gradient(135deg, var(--color-primary-deep) 0%, var(--color-primary) 58%, #1C4A40 100%);
}

.page-about__hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(247, 243, 233, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(247, 243, 233, 0.06) 1px, transparent 1px);
  background-size: 32px 32px;
  pointer-events: none;
}

.page-about__hero-frame {
  position: relative;
  max-width: calc(var(--container) + 48px);
  margin: 0 auto;
  background: var(--color-bg);
  border: 1px solid rgba(194, 155, 98, 0.7);
  outline: 1px solid rgba(47, 107, 94, 0.45);
  outline-offset: 6px;
  padding: 20px;
}

.page-about__hero-frame::after {
  content: "";
  position: absolute;
  top: 16px;
  right: 20px;
  width: 64px;
  height: 14px;
  background: repeating-linear-gradient(90deg, var(--color-accent) 0 2px, transparent 2px 6px);
  opacity: 0.65;
  pointer-events: none;
}

.page-about__breadcrumb {
  font-size: 13px;
  margin-bottom: 18px;
}

.page-about__breadcrumb a {
  color: var(--color-primary);
  text-decoration: none;
}

.page-about__breadcrumb a:hover,
.page-about__breadcrumb a:focus-visible {
  text-decoration: underline;
  outline: none;
}

.page-about__breadcrumb [aria-current="page"] {
  color: var(--color-ink);
}

.page-about__hero-grid {
  display: grid;
  gap: 20px;
}

.page-about__hero-media img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--color-border);
}

.page-about__kicker {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-primary);
  margin: 0 0 10px;
}

.page-about__hero-copy h1 {
  font-family: var(--font-title);
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 900;
  line-height: 1.18;
  letter-spacing: 0.02em;
  color: var(--color-ink);
  margin: 0 0 6px;
}

.page-about__hero-lead {
  font-size: clamp(1.05rem, 2.4vw, 1.4rem);
  color: var(--color-primary-deep);
  font-weight: 600;
  margin: 0 0 20px;
}

.page-about__manifesto {
  margin: 0;
  padding: 18px 20px;
  background: var(--color-bg-alt);
  border-left: 4px solid var(--color-accent);
}

.page-about__manifesto p {
  font-family: var(--font-title);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--color-ink);
  margin: 0 0 6px;
}

.page-about__manifesto footer {
  font-size: 13px;
  color: var(--about-ink-soft);
}

.page-about__hero-cta {
  margin-top: 22px;
  display: inline-block;
}

/* ===== 主体布局 ===== */
.page-about__body {
  display: block;
  padding: 48px 16px 72px;
  max-width: calc(var(--container) + 48px);
  margin: 0 auto;
}

/* ===== 目录 ===== */
.page-about__toc {
  margin-bottom: 40px;
  padding: 16px 18px;
  background: var(--color-bg-alt);
  border-left: 3px solid var(--color-accent);
}

.page-about__toc-title {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-primary);
  margin: 0 0 10px;
}

.page-about__toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
  counter-reset: about-toc;
  display: flex;
  flex-wrap: wrap;
  gap: 10px 20px;
}

.page-about__toc-list li {
  counter-increment: about-toc;
  position: relative;
  padding-left: 30px;
}

.page-about__toc-list li::before {
  content: counter(about-toc, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 0;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-accent);
}

.page-about__toc-list a {
  color: var(--color-ink);
  text-decoration: none;
  font-size: 15px;
  border-bottom: 1px solid transparent;
}

.page-about__toc-list a:hover,
.page-about__toc-list a:focus-visible {
  border-bottom-color: var(--color-primary);
  color: var(--color-primary);
}

/* ===== 内容列 ===== */
.page-about__content {
  min-width: 0;
}

.page-about__section {
  margin: 0 0 72px;
  scroll-margin-top: calc(var(--header-height) + 18px);
  padding: 28px 20px 32px;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: 0 4px 20px rgba(27, 27, 27, 0.04);
}

.page-about__section--alt {
  background: var(--color-bg-alt);
}

.page-about__section-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 2.6rem;
  line-height: 1;
  font-weight: 500;
  color: rgba(47, 107, 94, 0.18);
  margin: 0 0 6px;
}

.page-about__section-title {
  font-family: var(--font-title);
  font-size: clamp(1.4rem, 3vw, 2rem);
  font-weight: 900;
  line-height: 1.3;
  color: var(--color-ink);
  margin: 0 0 14px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--color-border);
  position: relative;
}

.page-about__section-title::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 52px;
  height: 3px;
  background: var(--color-accent);
}

.page-about__section-intro {
  font-size: 1.05rem;
  color: var(--about-ink-soft);
  margin: 0 0 20px;
  line-height: 1.75;
}

.page-about__section-body p {
  margin: 0 0 16px;
  line-height: 1.85;
  color: var(--color-ink);
}

/* ===== 旁注 ===== */
.page-about__aside {
  margin: 24px 0;
  padding: 16px 18px;
  background: rgba(247, 243, 233, 0.72);
  border-left: 3px solid var(--color-accent);
}

.page-about__section--alt .page-about__aside {
  background: rgba(255, 255, 255, 0.6);
}

.page-about__aside-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-primary);
  margin-bottom: 6px;
}

.page-about__aside p {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--color-ink);
}

/* ===== 三原则 ===== */
.page-about__principles {
  display: grid;
  gap: 16px;
  margin: 0 0 8px;
}

.page-about__principle {
  background: var(--color-bg);
  border-top: 3px solid var(--color-primary);
  border-radius: 0 0 var(--radius) var(--radius);
  padding: 22px 18px 20px;
}

.page-about__principle-num {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--color-accent);
  margin-bottom: 8px;
}

.page-about__principle h3 {
  font-family: var(--font-title);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-ink);
  margin: 0 0 10px;
}

.page-about__principle p {
  font-size: 14px;
  line-height: 1.75;
  color: var(--color-ink);
  margin: 0;
}

/* ===== 版本演进 ===== */
.page-about__versions-line {
  display: none;
  width: 100%;
  height: auto;
  margin: 8px 0 4px;
}

.page-about__version-row {
  display: grid;
  gap: 16px;
}

.page-about__version-item {
  position: relative;
  padding-left: 26px;
}

.page-about__version-item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-primary);
  border: 3px solid var(--color-bg);
  box-shadow: 0 0 0 2px var(--color-border);
  transition: transform var(--transition), box-shadow var(--transition);
}

.page-about__version-item::after {
  content: "";
  position: absolute;
  left: 5px;
  top: 28px;
  bottom: -8px;
  width: 2px;
  background: var(--color-border);
}

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

.page-about__version-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.06em;
  color: #fff;
  background: var(--color-primary);
  border-radius: 3px;
  padding: 2px 9px;
  margin-bottom: 10px;
}

.page-about__version-item:nth-child(1) .page-about__version-tag {
  background: var(--color-accent);
}

.page-about__version-item:nth-child(3) .page-about__version-tag {
  background: var(--color-alert);
}

.page-about__version-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 18px 16px;
  transition: border-color var(--transition), box-shadow var(--transition), transform var(--transition);
}

.page-about__version-card h3 {
  font-family: var(--font-title);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-ink);
  margin: 0 0 8px;
}

.page-about__version-card p {
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-ink);
  margin: 0;
}

.page-about__version-item:hover .page-about__version-card {
  border-color: var(--color-primary);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.page-about__version-item:hover::before {
  transform: scale(1.3);
  box-shadow: 0 0 0 4px rgba(47, 107, 94, 0.18);
}

/* ===== 图片框 ===== */
.page-about__figure {
  margin: 28px 0 8px;
}

.page-about__figure-frame {
  border: 1px solid var(--color-primary);
  outline: 1px solid var(--color-border);
  outline-offset: 4px;
  padding: 6px;
  background: #fff;
}

.page-about__figure-frame img {
  display: block;
  width: 100%;
  height: auto;
}

.page-about__figure figcaption {
  font-size: 13px;
  color: var(--about-ink-soft);
  padding: 10px 4px 0;
  line-height: 1.6;
}

/* ===== 服务边界 ===== */
.page-about__boundary {
  display: grid;
  gap: 24px;
}

.page-about__boundary-copy p {
  margin: 0 0 16px;
  line-height: 1.85;
  color: var(--color-ink);
}

.page-about__boundary-data {
  margin: 0;
  padding: 0;
  border-left: 3px solid var(--color-accent);
}

.page-about__boundary-data div {
  padding: 12px 16px;
  border-bottom: 1px solid var(--color-border);
}

.page-about__boundary-data div:last-child {
  border-bottom: none;
}

.page-about__boundary-data dt {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-primary);
  margin-bottom: 4px;
}

.page-about__boundary-data dd {
  margin: 0;
  font-size: 15px;
  font-weight: 600;
  color: var(--color-ink);
}

/* ===== 印鉴 ===== */
.page-about__seal {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-alert);
  border: 1.5px solid var(--color-alert);
  border-radius: 3px;
  padding: 3px 10px;
  letter-spacing: 0.08em;
  margin-top: 12px;
}

/* ===== 继续了解 ===== */
.page-about__explore {
  margin-top: 64px;
  padding-top: 28px;
  border-top: 2px solid var(--color-border);
}

.page-about__explore-title {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-primary);
  margin: 0 0 16px;
}

.page-about__explore-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about__explore-list li {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 12px 4px;
  border-bottom: 1px solid var(--color-border);
}

.page-about__explore-list a {
  color: var(--color-primary);
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
}

.page-about__explore-list a:hover,
.page-about__explore-list a:focus-visible {
  text-decoration: underline;
}

.page-about__explore-list span {
  font-size: 13px;
  color: var(--about-ink-soft);
}

/* ===== 锚点目标高亮 ===== */
.page-about__section:target {
  animation: page-about-target-fade 0.6s ease;
}

@keyframes page-about-target-fade {
  from {
    background-color: rgba(194, 155, 98, 0.28);
  }
  to {
    background-color: #fff;
  }
}

.page-about__section--alt:target {
  animation-name: page-about-target-fade-alt;
}

@keyframes page-about-target-fade-alt {
  from {
    background-color: rgba(47, 107, 94, 0.18);
  }
  to {
    background-color: var(--color-bg-alt);
  }
}

/* ===== 平板及以上 ===== */
@media (min-width: 768px) {
  .page-about__hero {
    padding: calc(var(--header-height) + 56px) 32px 72px;
  }

  .page-about__hero-frame {
    padding: 32px;
  }

  .page-about__hero-grid {
    grid-template-columns: 5fr 6fr;
    gap: 32px;
    align-items: center;
  }

  .page-about__body {
    padding: 64px 32px 96px;
  }

  .page-about__section {
    padding: 36px 36px 40px;
  }

  .page-about__principles {
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
  }

  .page-about__version-row {
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
  }

  .page-about__versions-line {
    display: block;
  }

  .page-about__version-item {
    padding-left: 0;
  }

  .page-about__version-item::before,
  .page-about__version-item::after {
    display: none;
  }

  .page-about__boundary {
    grid-template-columns: 3fr 2fr;
    gap: 32px;
    align-items: start;
  }

  .page-about__explore-list {
    grid-template-columns: 1fr 1fr;
    column-gap: 32px;
  }

  .page-about__figure {
    margin-top: 36px;
  }
}

/* ===== 桌面：右侧目录固定 ===== */
@media (min-width: 1024px) {
  .page-about__body {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 200px;
    gap: 52px;
    align-items: start;
  }

  .page-about__toc {
    grid-column: 2;
    grid-row: 1;
    position: sticky;
    top: calc(var(--header-height) + 24px);
    align-self: start;
    margin-bottom: 0;
    padding: 8px 0 8px 18px;
    background: transparent;
    border-left: 2px solid var(--color-accent);
  }

  .page-about__toc-list {
    flex-direction: column;
    gap: 14px;
  }

  .page-about__toc-list a {
    font-size: 14px;
  }

  .page-about__content {
    grid-column: 1;
    grid-row: 1;
  }

  .page-about__aside {
    max-width: 520px;
    margin-left: 0;
    margin-right: auto;
  }

  .page-about__section:nth-of-type(even) .page-about__aside {
    margin-left: auto;
    margin-right: 0;
  }
}