:root {
  --color-surface: #f0efef;
  --color-surface-alt: #e8e6e6;
  --color-surface-deep: #dcdad9;
  --color-ink: #4a423b;
  --color-ink-soft: #70665c;
  --color-ink-muted: #8b7f74;
  --color-line: #d2d0cf;
  --color-primary: #9c6a3a;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e4dcd6;
  --color-accent: #a06818;
  --color-accent-ink: #ffffff;
  --color-highlight: #e2d7c8;
  --color-focus: #965e0d;
  --color-contrast-surface: #201b15;
  --color-contrast-ink: #e7e5e4;
  --color-contrast-line: #4c4743;
  --color-contrast-accent: #de9021;
  --overlay-scrim: linear-gradient(180deg, rgba(32, 27, 21, 0.35) 0%, rgba(32, 27, 21, 0.72) 55%, rgba(32, 27, 21, 0.92) 100%);
  --font-heading: STZhongsong, "Source Han Serif SC", "Songti SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 10.4px;
  --text-sm: 13.9px;
  --text-base: 16px;
  --text-lg: 21.3px;
  --text-xl: 28.4px;
  --text-2xl: 37.9px;
  --text-3xl: 50.5px;
  --text-4xl: 67.3px;
  --text-display: clamp(38px, 7.7vw, 99px);
  --text-figure: clamp(31px, 5.5vw, 71px);
  --weight-heading: 782;
  --weight-body: 400;
  --leading-body: 1.68;
  --leading-heading: 1.16;
  --tracking-heading: 0.013em;
  --radius-sm: 0px;
  --radius-md: 1px;
  --radius-lg: 2px;
  --radius-pill: 2px;
  --border-thin: 1px;
  --border-thick: 3px;
  --shadow-1: 0 1px 0 rgba(74, 66, 59, 0.12);
  --shadow-2: 0 2px 0 rgba(74, 66, 59, 0.18);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1140px;
  --measure: 70ch;
  --gutter: 16px;
  --section-y: 74px;
  --section-y-lg: 104px;
}

/* =========================================================
   1. Reset
   ========================================================= */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background-color: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

img,
svg,
video { display: block; max-width: 100%; }

figure,
blockquote,
dl,
dd,
p { margin: 0; }

button,
input,
select,
textarea { font: inherit; color: inherit; }

a {
  color: var(--color-ink);
  text-decoration-color: var(--color-accent);
  text-underline-offset: 3px;
}

:focus-visible {
  outline: var(--border-thick) solid var(--color-focus);
  outline-offset: 2px;
}

/* =========================================================
   2. 中文排版基准
   ========================================================= */
h1, h2, h3, h4, h5, h6 {
  margin: 0 0 var(--space-2);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

h1 { font-size: var(--text-3xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }

p { margin: 0 0 var(--space-2); }
p:last-child { margin-bottom: 0; }

strong, b { font-weight: 700; }

.is-mono,
.num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.01em;
}

.display-title,
.cover__title {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  margin: 0;
}

.lede {
  font-size: var(--text-lg);
  line-height: 1.5;
  color: var(--color-ink-soft);
  max-width: 60ch;
}

.measure { max-width: var(--measure); }

.prose p { margin: 0 0 var(--space-2); }
.prose a {
  color: var(--color-ink);
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-decoration-thickness: 2px;
}
.prose a:hover { color: var(--color-accent); }
.prose ul,
.prose ol { margin: 0 0 var(--space-2); padding-left: 1.4em; }
.prose li { margin-bottom: 6px; }

/* =========================================================
   3. 跳过链接 / 容器 / 区块节奏
   ========================================================= */
.skip-link {
  position: absolute;
  left: var(--space-2);
  top: -220px;
  z-index: 200;
  padding: 10px 18px;
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  text-decoration: none;
  border: var(--border-thin) solid var(--color-contrast-accent);
  transition: top 0.18s ease;
}
.skip-link:focus { top: var(--space-2); }

.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--tight { padding-block: var(--space-6); }
.section--deep { background-color: var(--color-surface-deep); }

.section--contrast {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.section--contrast h1,
.section--contrast h2,
.section--contrast h3,
.section--contrast h4 { color: var(--color-contrast-ink); }
.section--contrast a { color: var(--color-contrast-ink); }
.section--contrast .lede { color: color-mix(in srgb, var(--color-contrast-ink) 74%, var(--color-contrast-surface)); }
.section--contrast .figure__value { color: var(--color-contrast-accent); }
.section--contrast .figure__label { color: color-mix(in srgb, var(--color-contrast-ink) 68%, var(--color-contrast-surface)); }
.section--contrast .rule-ticks { color: var(--color-contrast-line); }
.section--contrast .chapter__num {
  color: var(--color-contrast-accent);
  background-color: transparent;
  border-color: var(--color-contrast-line);
}
.section--contrast .chapter__kicker { color: color-mix(in srgb, var(--color-contrast-ink) 58%, var(--color-contrast-surface)); }

/* =========================================================
   4. 按钮
   ========================================================= */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 10px 18px;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.04em;
  line-height: 1.2;
  text-decoration: none;
  color: var(--color-ink);
  background-color: var(--color-surface);
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background-color 0.16s ease, color 0.16s ease, border-color 0.16s ease;
}
.btn:hover { background-color: var(--color-highlight); }
.btn--primary {
  color: var(--color-primary-ink);
  background-color: var(--color-primary);
  border-color: var(--color-primary);
}
.btn--primary:hover {
  background-color: color-mix(in srgb, var(--color-primary) 80%, var(--color-contrast-surface));
  border-color: color-mix(in srgb, var(--color-primary) 80%, var(--color-contrast-surface));
  color: var(--color-primary-ink);
}
.btn--ink {
  color: var(--color-contrast-ink);
  background-color: var(--color-contrast-surface);
  border-color: var(--color-contrast-surface);
}
.btn--ink:hover { background-color: var(--color-primary); border-color: var(--color-primary); }
.btn--ghost { background-color: transparent; }
.btn--ghost:hover { background-color: var(--color-primary-soft); }
.btn--sm { padding: 7px 13px; font-size: var(--text-xs); letter-spacing: 0.08em; }

/* =========================================================
   5. 站点头部：悬浮胶囊浮岛 + 双线框
   ========================================================= */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  padding-block: var(--space-2);
  pointer-events: none;
}

.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--scroll-progress, 0%);
  height: 3px;
  background-color: var(--color-accent);
  z-index: 90;
  pointer-events: none;
}

.site-header__island {
  position: relative;
  pointer-events: auto;
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-height: 62px;
  padding-inline: var(--space-3);
  background-color: var(--color-surface);
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-pill);
}

.site-header__island::after {
  content: "";
  position: absolute;
  inset: 3px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  pointer-events: none;
}

/* 品牌 */
.brand {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding-block: var(--space-1);
  text-decoration: none;
  color: var(--color-ink);
  position: relative;
  z-index: 1;
}

.brand__mark {
  position: relative;
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1;
  color: var(--color-primary-ink);
  background-color: var(--color-primary);
}

.brand__mark::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: 0;
  width: 12px;
  height: 12px;
  background-color: var(--color-accent);
}

.brand__stack {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.brand__line {
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  line-height: 1.2;
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.brand__since {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  line-height: 1;
  color: var(--color-ink-muted);
}

/* 移动端切换 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  margin-inline-start: auto;
  padding: 9px 13px;
  background-color: transparent;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-ink-soft);
  cursor: pointer;
  position: relative;
  z-index: 1;
}
.nav-toggle[aria-expanded="true"] {
  border-color: var(--color-accent);
  color: var(--color-ink);
}
.nav-toggle__bars {
  display: grid;
  gap: 3px;
  width: 16px;
}
.nav-toggle__bars i {
  display: block;
  height: 2px;
  background-color: currentColor;
}
.nav-toggle__bars i:nth-child(2) { width: 68%; }
.nav-toggle__label { line-height: 1; }

/* 导航 */
.site-nav {
  margin-inline-start: auto;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  position: relative;
  z-index: 1;
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: 0;
  margin: 0;
  padding: 0;
  list-style: none;
}

.site-nav__link {
  position: relative;
  display: block;
  padding: 9px 11px;
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
  text-decoration: none;
  transition: color 0.16s ease;
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 11px;
  right: 11px;
  bottom: 4px;
  height: 2px;
  background-color: var(--color-accent);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.2s ease;
}

.site-nav__link:hover { color: var(--color-ink); }
.site-nav__link:hover::after,
.site-nav__link[aria-current="page"]::after { transform: scaleX(1); }
.site-nav__link[aria-current="page"] {
  color: var(--color-ink);
  font-weight: 600;
}

.site-nav__cta { margin-inline-start: var(--space-1); }

/* =========================================================
   6. 站点页脚：反色 + 双线收口
   ========================================================= */
.site-footer {
  position: relative;
  margin-top: var(--section-y-lg);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thick) solid var(--color-contrast-accent);
}

.site-footer::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 7px;
  height: var(--border-thin);
  background-color: var(--color-contrast-line);
}

.site-footer__inner {
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--section-y) var(--space-3) var(--space-4);
}

.site-footer__top {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-6) var(--space-4);
  padding-bottom: var(--space-6);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.site-footer__brand { display: grid; gap: var(--space-1); align-content: start; }

.site-footer__brandline {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.25;
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}

.site-footer__mark { color: var(--color-contrast-accent); }

.site-footer__note {
  margin: 0;
  max-width: 38ch;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 66%, var(--color-contrast-surface));
}

.site-footer__col { min-width: 0; }

.site-footer__title {
  margin: 0 0 var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 400;
  letter-spacing: 0.2em;
  color: var(--color-contrast-accent);
}
.site-footer__title--gap { margin-top: var(--space-4); }

.site-footer__links {
  display: grid;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.site-footer__links a {
  display: inline-block;
  padding-bottom: 2px;
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
  text-decoration: none;
  border-bottom: var(--border-thin) solid transparent;
  transition: color 0.16s ease, border-color 0.16s ease;
}
.site-footer__links a:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-line);
}

.site-footer__contact-list {
  display: grid;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.site-footer__contact-list li {
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr);
  gap: var(--space-2);
  align-items: baseline;
  font-size: var(--text-sm);
}

.site-footer__klabel {
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: color-mix(in srgb, var(--color-contrast-ink) 50%, var(--color-contrast-surface));
}

.site-footer__kvalue {
  color: var(--color-contrast-ink);
  overflow-wrap: anywhere;
}

.site-footer__bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding-top: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, var(--color-contrast-surface));
}
.site-footer__bottom p { margin: 0; }
.site-footer__icp { white-space: nowrap; }

/* =========================================================
   7. 通用印刷组件
   ========================================================= */

/* 双线票据框 */
.press-frame {
  position: relative;
  padding: var(--space-4);
  background-color: var(--color-surface);
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-sm);
}
.press-frame::after {
  content: "";
  position: absolute;
  inset: 4px;
  border: var(--border-thin) solid var(--color-line);
  pointer-events: none;
}
.press-frame > * { position: relative; z-index: 1; }

.press-frame--deep { background-color: var(--color-surface-alt); }

.press-frame--contrast {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-color: var(--color-contrast-accent);
}
.press-frame--contrast::after { border-color: var(--color-contrast-line); }
.press-frame--contrast h2,
.press-frame--contrast h3 { color: var(--color-contrast-ink); }
.press-frame--contrast .figure__value { color: var(--color-contrast-accent); }
.press-frame--contrast .figure__label { color: color-mix(in srgb, var(--color-contrast-ink) 66%, var(--color-contrast-surface)); }

/* 刻度分隔 */
.rule-ticks {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-block: var(--space-4);
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  white-space: nowrap;
}
.rule-ticks::before,
.rule-ticks::after {
  content: "";
  flex: 1 1 0;
  height: 7px;
  background-image: repeating-linear-gradient(90deg, currentColor 0 1px, transparent 1px 11px);
  border-bottom: var(--border-thin) solid currentColor;
  opacity: 0.55;
}

/* 章节编号体系 */
.chapter {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: var(--space-3);
  align-items: start;
  margin-bottom: var(--space-4);
}

.chapter__num {
  display: inline-block;
  padding: 6px 10px;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-variant-numeric: tabular-nums;
  line-height: 1;
  color: var(--color-accent);
  background-color: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
}

.chapter__kicker {
  margin: 0 0 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  color: var(--color-ink-muted);
}

.chapter__title { margin: 0; font-size: var(--text-2xl); }

/* 印刷标签 */
.tag {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  line-height: 1.6;
  white-space: nowrap;
  color: var(--color-ink-soft);
  background-color: var(--color-primary-soft);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
}
.tag::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(45deg, color-mix(in srgb, var(--color-ink) 8%, transparent) 0 1px, transparent 1px 4px);
  pointer-events: none;
}
.tag--accent {
  color: var(--color-accent-ink);
  background-color: var(--color-accent);
  border-color: var(--color-accent);
}
.tag--solid {
  color: var(--color-contrast-ink);
  background-color: var(--color-contrast-surface);
  border-color: var(--color-contrast-surface);
}

/* 大数字锚点 */
.figure {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.figure__value {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  line-height: 0.94;
  letter-spacing: -0.02em;
  color: var(--color-accent);
}
.figure__label {
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-ink-soft);
}
.figure--sm .figure__value { font-size: var(--text-2xl); }

.figure-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(132px, 1fr));
  gap: var(--space-3);
  padding-block: var(--space-3);
  border-top: var(--border-thin) solid var(--color-line);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.section--contrast .figure-row { border-color: var(--color-contrast-line); }

/* 编号索引条 */
.index-strip {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: var(--border-thin) solid var(--color-line);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.index-strip__item {
  display: flex;
  align-items: baseline;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-3);
  border-right: var(--border-thin) solid var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-soft);
}
.index-strip__item:last-child { border-right: 0; }
.index-strip__item b {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-accent);
}

/* 封面 */
.cover {
  padding-block: var(--section-y-lg) var(--section-y);
  text-align: center;
}
.cover__title { margin-inline: auto; max-width: 22ch; }
.cover__lede {
  margin: var(--space-3) auto 0;
  max-width: 56ch;
  font-size: var(--text-lg);
  color: var(--color-ink-soft);
}
.cover__meta {
  margin-top: var(--space-4);
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-1);
}

/* 面包屑 */
.breadcrumb {
  margin: 0 0 var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}
.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  margin: 0;
  padding: 0;
  list-style: none;
}
.breadcrumb li { display: inline-flex; align-items: center; gap: var(--space-1); }
.breadcrumb li + li::before { content: "›"; color: var(--color-line); }
.breadcrumb a { color: var(--color-ink-soft); text-decoration: none; }
.breadcrumb a:hover { color: var(--color-accent); }
.breadcrumb [aria-current="page"] { color: var(--color-ink); }

/* 数据表 */
.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
  line-height: 1.35;
}
.data-table caption {
  padding-bottom: var(--space-2);
  text-align: left;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}
.data-table th,
.data-table td {
  padding: 10px 12px;
  text-align: left;
  border-bottom: var(--border-thin) solid var(--color-line);
  vertical-align: top;
}
.data-table thead th {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.1em;
  color: var(--color-ink);
  background-color: var(--color-primary-soft);
  border-top: var(--border-thin) solid var(--color-ink);
  border-bottom: var(--border-thin) solid var(--color-ink);
}
.data-table tbody tr:nth-child(even) { background-color: var(--color-surface-alt); }
.data-table tbody tr { transition: background-color 0.14s ease; }
.data-table tbody tr:hover { background-color: var(--color-highlight); }
.data-table .is-num { text-align: right; }
.data-table td.is-num,
.data-table th.is-num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}
.data-table tbody tr[aria-current="true"] { background-color: var(--color-highlight); }
.data-table tbody tr[aria-current="true"] td:first-child {
  box-shadow: inset var(--border-thick) 0 0 var(--color-accent);
}

.section--contrast .data-table th,
.section--contrast .data-table td { border-color: var(--color-contrast-line); }
.section--contrast .data-table thead th {
  color: var(--color-contrast-ink);
  background-color: color-mix(in srgb, var(--color-contrast-accent) 22%, var(--color-contrast-surface));
  border-color: var(--color-contrast-accent);
}
.section--contrast .data-table tbody tr:nth-child(even) {
  background-color: color-mix(in srgb, var(--color-contrast-ink) 6%, var(--color-contrast-surface));
}
.section--contrast .data-table tbody tr:hover { background-color: color-mix(in srgb, var(--color-contrast-accent) 14%, var(--color-contrast-surface)); }

/* 图片容器 */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  isolation: isolate;
  aspect-ratio: 16 / 9;
  background-color: var(--color-surface-deep);
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-sm);
}
.media-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: grayscale(100%) sepia(34%) contrast(108%) brightness(94%);
  mix-blend-mode: multiply;
}
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--flush { border: 0; border-radius: 0; }

.media-frame--overlay::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: var(--overlay-scrim);
  pointer-events: none;
}

.media-frame__caption {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 2;
  padding: var(--space-3);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: 1.5;
}
.media-frame__caption .tag { margin-right: var(--space-1); }

/* =========================================================
   8. 栅格工具：非对称优先
   ========================================================= */
.grid { display: grid; gap: var(--space-3); }
.grid--2,
.grid--asym,
.grid--asym-r { grid-template-columns: minmax(0, 1fr); }
.grid--loose { gap: var(--space-6); }

@media (min-width: 700px) {
  .grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (min-width: 900px) {
  .grid--asym { grid-template-columns: 7fr 5fr; }
  .grid--asym-r { grid-template-columns: 5fr 7fr; }
}

/* =========================================================
   9. 滚动显现
   ========================================================= */
html.has-js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.5s ease, transform 0.5s ease;
  transition-delay: var(--reveal-delay, 0ms);
}
html.has-js [data-reveal].is-revealed {
  opacity: 1;
  transform: none;
}

/* =========================================================
   10. 响应式
   ========================================================= */
@media (max-width: 900px) {
  .site-header { padding-block: var(--space-1); }
  .site-header__island { padding-inline: var(--space-2); min-height: 56px; }
  .brand__mark { width: 32px; height: 32px; font-size: var(--text-base); }

  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: absolute;
    top: calc(100% + var(--space-1));
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: var(--space-3);
    margin: 0;
    padding: var(--space-3) var(--space-3) var(--space-4);
    background-color: var(--color-surface);
    border: var(--border-thin) solid var(--color-ink);
    border-radius: var(--radius-sm);
  }
  .site-nav[data-open] { display: flex; }

  .site-nav__list { flex-direction: column; align-items: stretch; }
  .site-nav__link {
    padding: 13px 4px;
    font-size: var(--text-base);
    border-bottom: var(--border-thin) solid var(--color-line);
  }
  .site-nav__link::after {
    left: 4px;
    right: auto;
    width: 22px;
    bottom: 8px;
  }
  .site-nav__cta { justify-content: center; }
}

@media (max-width: 640px) {
  .container { padding-inline: var(--space-2); }
  .brand__since { display: none; }
  .chapter { gap: var(--space-2); }
  .press-frame { padding: var(--space-3); }
  .press-frame::after { inset: 3px; }
  .figure-row { grid-template-columns: repeat(auto-fit, minmax(110px, 1fr)); }
  .index-strip__item { padding: var(--space-1) var(--space-2); }
  .site-footer__contact-list li { grid-template-columns: 40px minmax(0, 1fr); }
  .site-footer__bottom { justify-content: flex-start; }
}

@media (min-width: 720px) {
  .site-footer__top { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 1000px) {
  .site-footer__top { grid-template-columns: 1.35fr 0.8fr 0.85fr 1.15fr; }
}

/* =========================================================
   11. 减少动态
   ========================================================= */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  html.has-js [data-reveal] {
    opacity: 1;
    transform: none;
    transition: none;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}