/* ============================================================
   易丰会馆 · 共享外壳样式  /assets/site.css
   结构：Reset → 变量 → 基础排版 → 顶栏 → 轨道导航 → 页脚
        → 通用组件 → 图片容器 → 响应式 → 动效降级
   ============================================================ */

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body, h1, h2, h3, h4, h5, h6, p, ul, ol, dl, dd, figure, blockquote, pre { margin: 0; }
ul, ol { padding: 0; list-style: none; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }
a { color: inherit; text-decoration: none; }
img, svg, video, canvas { display: block; max-width: 100%; }
table { border-collapse: collapse; width: 100%; }
details > summary { list-style: none; cursor: pointer; }
details > summary::-webkit-details-marker { display: none; }

/* ---------- 变量 ---------- */
:root {
  /* 色彩：山西古建灰砖 + 木构暖褐 + 鎏金铜 + 暗朱砂 + 石青黛蓝 */
  --c-brick:        #3A3A38;
  --c-ink:          #1E1E1C;
  --c-wood:         #6B4A2F;
  --c-wood-light:   #8C6A46;
  --c-brass:        #C9A050;
  --c-brass-hi:     #E4C177;
  --c-cinnabar:     #9E3B32;
  --c-cinnabar-lt:  #C96B5C;
  --c-stone:        #4A6E7E;
  --c-dai:          #2E4256;
  --c-paper:        #EDE4D3;
  --c-text:         #2A2724;

  --c-line:         rgba(201, 160, 80, .28);
  --c-line-soft:    rgba(237, 228, 211, .10);
  --c-line-faint:   rgba(237, 228, 211, .07);
  --c-on-dark:      rgba(237, 228, 211, .84);
  --c-on-dark-dim:  rgba(237, 228, 211, .52);

  /* 字体 */
  --font-serif: "Songti SC", "STSong", "Noto Serif SC", "Source Han Serif SC", "SimSun", Georgia, serif;
  --font-sans:  "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono:  ui-monospace, "SFMono-Regular", "JetBrains Mono", Menlo, Consolas, "Courier New", monospace;

  /* 尺度 */
  --header-h: 74px;
  --rail-w:   232px;
  --maxw:     1180px;
  --gap:      clamp(20px, 3.2vw, 48px);
  --radius:   2px;

  --ease: cubic-bezier(.22, .61, .36, 1);
  --dur:  .28s;
}

@media (max-width: 767px) {
  :root { --header-h: 64px; }
}

/* ---------- 基础排版 ---------- */
body {
  background: var(--c-brick);
  color: var(--c-on-dark);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.9;
  min-height: 100vh;
  padding-top: var(--header-h);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

@media (min-width: 1024px) {
  body { padding-left: var(--rail-w); }
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  font-weight: 600;
  line-height: 1.45;
  letter-spacing: .1em;
  color: var(--c-paper);
}

h1 { font-size: clamp(26px, 3.6vw, 40px); }
h2 { font-size: clamp(21px, 2.6vw, 28px); }
h3 { font-size: clamp(17px, 1.8vw, 20px); }

p { line-height: 1.9; }

::selection { background: rgba(201, 160, 80, .34); color: var(--c-paper); }

#main-content { scroll-margin-top: calc(var(--header-h) + 20px); }

:focus-visible {
  outline: 2px solid var(--c-brass-hi);
  outline-offset: 3px;
  border-radius: var(--radius);
}

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

/* ---------- 跳转链接 ---------- */
.skip-link {
  position: fixed;
  top: 10px; left: 10px;
  z-index: 200;
  padding: 10px 20px;
  background: var(--c-brass);
  color: var(--c-ink);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: .08em;
  border-radius: var(--radius);
  transform: translateY(-160%);
  transition: transform .2s var(--ease);
}
.skip-link:focus { transform: translateY(0); }

/* ============================================================
   顶栏
   ============================================================ */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-h);
  z-index: 90;
}

.brand-bar {
  position: relative;
  height: var(--header-h);
  background: var(--c-ink);
  border-bottom: 1px solid var(--c-line);
}

.brand-bar__inner {
  height: 100%;
  display: flex;
  align-items: center;
  gap: 16px;
  padding-inline: clamp(16px, 2.6vw, 32px);
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
  flex: none;
}

.brand__seal {
  width: 38px; height: 38px;
  flex: none;
  display: grid;
  place-items: center;
  font-family: var(--font-serif);
  font-size: 20px;
  font-weight: 600;
  line-height: 1;
  color: var(--c-paper);
  background: linear-gradient(150deg, #B8483C, var(--c-cinnabar) 58%, #7C2B24);
  border-radius: var(--radius);
  box-shadow: inset 0 0 0 1px rgba(30, 30, 28, .4), 0 1px 0 rgba(255, 255, 255, .12);
}

.brand__text {
  display: flex;
  flex-direction: column;
  gap: 3px;
  min-width: 0;
  line-height: 1.15;
}

.brand__name {
  font-family: var(--font-serif);
  font-size: 19px;
  font-weight: 600;
  letter-spacing: .16em;
  color: var(--c-paper);
  white-space: nowrap;
}

.brand__note {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: .1em;
  color: var(--c-brass);
  opacity: .82;
  white-space: nowrap;
}

.brand-bar__meta {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 8px;
}

.meta-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 12px;
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  background: rgba(201, 160, 80, .06);
  white-space: nowrap;
}

.meta-chip__label {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: .18em;
  color: var(--c-brass);
}

.meta-chip__value {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .04em;
  color: rgba(237, 228, 211, .88);
}

/* 移动端抽屉按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  margin-left: auto;
  padding: 9px 14px;
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  color: var(--c-paper);
  font-size: 13px;
  letter-spacing: .12em;
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}
.nav-toggle:hover { border-color: var(--c-brass); background: rgba(201, 160, 80, .08); }

.nav-toggle__bars {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 18px; height: 14px;
  flex: none;
}
.nav-toggle__bars i {
  display: block;
  height: 1.5px;
  background: var(--c-brass);
  border-radius: 1px;
  transition: transform var(--dur) var(--ease), opacity var(--dur) var(--ease);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(1) { transform: translateY(5.5px) rotate(38deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(3) { transform: translateY(-5.5px) rotate(-38deg); }

.nav-toggle__text {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .2em;
}

/* 阅读进度条 */
.scroll-meter {
  position: absolute;
  left: 0; right: 0; bottom: -1px;
  height: 2px;
  background: rgba(237, 228, 211, .07);
  overflow: hidden;
}
.scroll-meter__bar {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--c-cinnabar), var(--c-brass) 45%, var(--c-brass-hi));
}

/* ============================================================
   侧边轨道导航
   ============================================================ */
.site-nav {
  position: fixed;
  top: var(--header-h);
  left: 0;
  z-index: 85;
  width: min(340px, 86vw);
  height: calc(100vh - var(--header-h));
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 22px 0 30px;
  background: var(--c-ink);
  border-right: 1px solid var(--c-line);
  transform: translateX(-102%);
  visibility: hidden;
  transition: transform .34s var(--ease), visibility .34s var(--ease);
}
.site-nav[data-open] {
  transform: translateX(0);
  visibility: visible;
  box-shadow: 26px 0 60px -34px rgba(0, 0, 0, .95);
}

.site-nav__head {
  padding: 0 24px 16px;
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: .24em;
  color: var(--c-brass);
  opacity: .7;
  border-bottom: 1px solid var(--c-line-faint);
}

.site-nav__list {
  display: flex;
  flex-direction: column;
  padding: 12px 0 0;
}

.site-nav__link {
  position: relative;
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 13px 24px;
  border-left: 2px solid transparent;
  font-size: 15px;
  letter-spacing: .08em;
  color: rgba(237, 228, 211, .68);
  transition: color var(--dur) var(--ease), background-color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 24px; right: 24px; bottom: 0;
  height: 1px;
  background: linear-gradient(90deg, var(--c-line-faint), transparent 78%);
}

.site-nav__link:hover {
  color: var(--c-paper);
  background: rgba(201, 160, 80, .07);
}

.site-nav__link[aria-current="page"] {
  color: var(--c-brass-hi);
  border-left-color: var(--c-brass);
  background: linear-gradient(90deg, rgba(201, 160, 80, .16), transparent 72%);
}

.site-nav__num {
  flex: none;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .12em;
  color: var(--c-brass);
  opacity: .68;
  transition: opacity var(--dur) var(--ease);
}
.site-nav__link:hover .site-nav__num,
.site-nav__link[aria-current="page"] .site-nav__num { opacity: 1; }

.site-nav__label { display: block; }

.site-nav__foot {
  margin-top: auto;
  padding: 22px 22px 0;
  display: grid;
  gap: 10px;
  border-top: 1px solid var(--c-line-faint);
}

.rail-download {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 11px 14px;
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  background: rgba(201, 160, 80, .05);
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--c-brass);
  transition: background-color var(--dur) var(--ease), color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.rail-download::after {
  content: "↓";
  font-family: var(--font-mono);
  opacity: .85;
}
.rail-download:hover {
  background: rgba(201, 160, 80, .16);
  border-color: var(--c-brass);
  color: var(--c-brass-hi);
}

.rail-top {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 10px;
  border: 1px solid var(--c-line-faint);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .16em;
  color: var(--c-on-dark-dim);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.rail-top:hover { color: var(--c-brass-hi); border-color: var(--c-line); }

/* ============================================================
   页脚
   ============================================================ */
.site-footer {
  position: relative;
  margin-top: clamp(56px, 8vw, 104px);
  background: var(--c-ink);
  border-top: 1px solid var(--c-line);
  color: var(--c-on-dark);
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--c-cinnabar), var(--c-wood) 30%, var(--c-brass) 62%, var(--c-dai));
  opacity: .5;
}

.site-footer__inner {
  max-width: var(--maxw);
  margin-inline: auto;
  padding: clamp(44px, 6vw, 78px) var(--gap) 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(32px, 4vw, 52px);
}

.fcol { min-width: 0; }
.fcol--hall { min-width: 0; }
.fcol--index { min-width: 0; }

.fcol__title {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 16px;
  font-family: var(--font-serif);
  font-size: 15.5px;
  font-weight: 600;
  letter-spacing: .2em;
  color: var(--c-brass);
}
.fcol__title::before {
  content: "";
  flex: none;
  width: 16px; height: 7px;
  background:
    linear-gradient(var(--c-brass), var(--c-brass)) 0 0 / 100% 1px no-repeat,
    linear-gradient(var(--c-brass), var(--c-brass)) 0 100% / 100% 1px no-repeat;
  opacity: .85;
}

.fcol__lead {
  margin-bottom: 14px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--c-on-dark);
}

.fcol__note {
  margin-top: 14px;
  font-size: 12.5px;
  line-height: 1.85;
  color: var(--c-on-dark-dim);
}

.fcol__list { margin-top: 6px; }

.fcol__list li {
  display: flex;
  gap: 12px;
  padding: 9px 0;
  border-bottom: 1px solid var(--c-line-faint);
  font-size: 13.5px;
}

.fcol__k {
  flex: none;
  width: 74px;
  padding-top: 2px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--c-brass);
  opacity: .9;
}

.fcol__v {
  min-width: 0;
  line-height: 1.75;
  color: var(--c-on-dark);
  word-break: break-word;
}

/* 第二栏 · 内地测试版下载固定入口 */
.fcol--gate {
  position: relative;
  padding: clamp(20px, 2.4vw, 28px);
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  background:
    radial-gradient(120% 90% at 0% 0%, rgba(158, 59, 50, .16), transparent 62%),
    radial-gradient(120% 90% at 100% 100%, rgba(74, 110, 126, .16), transparent 62%),
    rgba(107, 74, 47, .14);
}
.fcol--gate::before,
.fcol--gate::after {
  content: "";
  position: absolute;
  width: 15px; height: 15px;
  border: 1px solid var(--c-brass);
  opacity: .55;
  pointer-events: none;
}
.fcol--gate::before { top: -1px; left: -1px; border-right: 0; border-bottom: 0; }
.fcol--gate::after  { bottom: -1px; right: -1px; border-left: 0; border-top: 0; }

.fcol--gate .fcol__title { margin-bottom: 12px; }

.fcol__links {
  display: flex;
  flex-direction: column;
  margin-top: 4px;
}

.fcol__link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 11px 0;
  border-bottom: 1px solid var(--c-line-faint);
  font-size: 14px;
  letter-spacing: .06em;
  color: rgba(237, 228, 211, .78);
  transition: color var(--dur) var(--ease), padding-left var(--dur) var(--ease);
}
.fcol__link::after {
  content: "→";
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--c-brass);
  opacity: .55;
  transition: opacity var(--dur) var(--ease);
}
.fcol__link:hover {
  color: var(--c-brass-hi);
  padding-left: 6px;
}
.fcol__link:hover::after { opacity: 1; }

.site-footer__base {
  max-width: var(--maxw);
  margin: clamp(34px, 4vw, 54px) auto 0;
  padding: 18px var(--gap) 28px;
  border-top: 1px solid var(--c-line-soft);
  display: flex;
  flex-wrap: wrap;
  gap: 8px 24px;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .04em;
  color: var(--c-on-dark-dim);
}

.site-footer__copy { color: rgba(237, 228, 211, .6); }
.site-footer__scope { max-width: 62ch; }

/* ============================================================
   通用组件
   ============================================================ */
.canvas {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--gap);
}

.section { padding-block: clamp(48px, 7vw, 96px); }

.section--paper {
  background: var(--c-paper);
  color: var(--c-text);
}
.section--paper h1,
.section--paper h2,
.section--paper h3,
.section--paper h4 { color: var(--c-text); }

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 12px 26px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: .14em;
  line-height: 1.4;
  transition: background-color var(--dur) var(--ease), color var(--dur) var(--ease),
              border-color var(--dur) var(--ease), transform var(--dur) var(--ease),
              box-shadow var(--dur) var(--ease);
}

.btn--brass {
  background: linear-gradient(150deg, var(--c-brass-hi), var(--c-brass) 70%, #AE8A3D);
  color: var(--c-ink);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .28), 0 8px 22px -16px rgba(201, 160, 80, .9);
}
.btn--brass:hover {
  background: var(--c-brass-hi);
  transform: translateY(-1px);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .36), 0 12px 26px -14px rgba(201, 160, 80, 1);
}
.btn--brass:active { transform: translateY(0); }

.btn--outline {
  border-color: var(--c-line);
  color: var(--c-paper);
}
.btn--outline:hover {
  border-color: var(--c-brass);
  color: var(--c-brass-hi);
  background: rgba(201, 160, 80, .1);
}

.btn--block { display: flex; width: 100%; }

/* 面包屑 */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0;
  padding: 18px 0;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--c-on-dark-dim);
}
.breadcrumb li {
  display: flex;
  align-items: center;
}
.breadcrumb li + li::before {
  content: "/";
  margin: 0 10px;
  color: var(--c-brass);
  opacity: .5;
}
.breadcrumb a {
  color: var(--c-brass);
  transition: color var(--dur) var(--ease);
}
.breadcrumb a:hover { color: var(--c-brass-hi); }
.breadcrumb [aria-current="page"] { color: var(--c-paper); }

/* 正文排版 */
.prose {
  font-size: 16px;
  line-height: 1.9;
  color: var(--c-on-dark);
}
.prose > * + * { margin-top: 1.05em; }

.prose h2 {
  margin-top: 1.7em;
  font-size: clamp(19px, 2.3vw, 25px);
}
.prose h3 {
  margin-top: 1.5em;
  font-size: 17px;
  color: var(--c-brass);
}
.prose h1 + *,
.prose h2 + *,
.prose h3 + * { margin-top: .7em; }

.prose p { max-width: 74ch; }

.prose a {
  color: var(--c-brass);
  border-bottom: 1px solid var(--c-line);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.prose a:hover { color: var(--c-brass-hi); border-bottom-color: var(--c-brass); }

.prose strong { color: var(--c-paper); font-weight: 600; }

.prose ul, .prose ol {
  padding-left: 0;
  display: block;
}
.prose ul li {
  position: relative;
  padding-left: 1.15em;
}
.prose ul li + li { margin-top: .45em; }
.prose ul li::before {
  content: "";
  position: absolute;
  left: 0; top: .88em;
  width: 7px; height: 1px;
  background: var(--c-brass);
}
.prose ol { counter-reset: prose-ol; }
.prose ol li {
  counter-increment: prose-ol;
  position: relative;
  padding-left: 2em;
}
.prose ol li + li { margin-top: .45em; }
.prose ol li::before {
  content: counter(prose-ol, decimal-leading-zero);
  position: absolute;
  left: 0; top: .1em;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--c-brass);
}

.prose blockquote {
  padding: 4px 0 4px 18px;
  border-left: 2px solid var(--c-cinnabar-lt);
  color: rgba(237, 228, 211, .78);
}

.prose--paper { color: var(--c-text); }
.prose--paper h2,
.prose--paper h3 { color: var(--c-text); }
.prose--paper strong { color: var(--c-text); }
.prose--paper a { color: var(--c-cinnabar); border-bottom-color: rgba(158, 59, 50, .34); }
.prose--paper a:hover { color: var(--c-cinnabar); border-bottom-color: var(--c-cinnabar); }
.prose--paper blockquote { border-left-color: var(--c-cinnabar); color: rgba(42, 39, 36, .8); }

/* 小标签 / 索引编号 / 描边标签 */
.kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--c-brass);
}
.kicker::before {
  content: "";
  width: 22px; height: 1px;
  background: currentColor;
  opacity: .7;
}

.index-num {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .14em;
  color: var(--c-brass);
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 11px;
  border: 1px solid rgba(201, 107, 92, .46);
  border-radius: 999px;
  font-size: 12px;
  letter-spacing: .1em;
  line-height: 1.6;
  color: var(--c-cinnabar-lt);
  background: rgba(158, 59, 50, .1);
}
.section--paper .tag {
  border-color: rgba(158, 59, 50, .42);
  color: var(--c-cinnabar);
  background: rgba(158, 59, 50, .08);
}

/* 纸面卡片 */
.stack-card {
  position: relative;
  padding: clamp(20px, 2.6vw, 32px);
  border-radius: var(--radius);
  background: var(--c-paper);
  color: var(--c-text);
  box-shadow: 7px 7px 0 -1px rgba(107, 74, 47, .5), 0 20px 40px -30px rgba(0, 0, 0, .95);
}
.stack-card h2,
.stack-card h3 { color: var(--c-text); }
.stack-card a { color: var(--c-cinnabar); }

/* 规则条目 */
.rule-list { display: grid; gap: 0; }

.rule-item {
  display: grid;
  grid-template-columns: 46px 1fr;
  gap: 16px;
  padding: 16px 0;
  border-bottom: 1px solid var(--c-line-soft);
}
.rule-item:first-child { border-top: 1px solid var(--c-line-soft); }

.rule-item__num {
  padding-top: 3px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--c-brass);
}

.rule-item__body {
  font-size: 15px;
  line-height: 1.9;
  color: var(--c-on-dark);
}

.section--paper .rule-item { border-color: rgba(42, 39, 36, .12); }
.section--paper .rule-item__num { color: var(--c-cinnabar); }
.section--paper .rule-item__body { color: var(--c-text); }

/* 版本时间轴 */
.timeline {
  display: grid;
  padding-left: 22px;
  border-left: 1px solid var(--c-line);
}

.timeline__item {
  position: relative;
  padding-bottom: 28px;
}
.timeline__item:last-child { padding-bottom: 0; }

.timeline__item::before {
  content: "";
  position: absolute;
  left: -27px; top: 9px;
  width: 9px; height: 9px;
  border-radius: 50%;
  background: var(--c-ink);
  border: 1px solid var(--c-brass);
}
.timeline__item:first-child::before {
  background: var(--c-brass);
  box-shadow: 0 0 0 4px rgba(201, 160, 80, .16);
}

.timeline__version {
  display: inline-block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--c-brass);
}

/* 分段标签页 */
.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  border-bottom: 1px solid var(--c-line);
}

.tab {
  position: relative;
  padding: 11px 18px;
  border: 1px solid transparent;
  border-bottom: 0;
  border-radius: var(--radius) var(--radius) 0 0;
  font-size: 14px;
  letter-spacing: .1em;
  color: rgba(237, 228, 211, .62);
  transition: color var(--dur) var(--ease), background-color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.tab:hover { color: var(--c-paper); background: rgba(201, 160, 80, .06); }
.tab[aria-selected="true"] {
  color: var(--c-brass-hi);
  background: rgba(201, 160, 80, .1);
  border-color: var(--c-line);
}
.tab[aria-selected="true"]::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -1px;
  height: 2px;
  background: var(--c-brass);
}

.tabpanel { padding-top: 26px; }
.tabpanel[hidden] { display: none; }

/* 印刷角标 */
.print-frame { position: relative; }
.print-frame::before,
.print-frame::after {
  content: "";
  position: absolute;
  width: 16px; height: 16px;
  border: 1px solid var(--c-brass);
  opacity: .5;
  pointer-events: none;
}
.print-frame::before { top: -1px; left: -1px; border-right: 0; border-bottom: 0; }
.print-frame::after  { bottom: -1px; right: -1px; border-left: 0; border-top: 0; }

/* ============================================================
   图片容器基础规则（供页面阶段放置占位图片）
   ============================================================ */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  width: 100%;
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  background: linear-gradient(150deg, #2A2A28, var(--c-ink));
}

.media-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  box-shadow:
    inset 0 0 0 1px rgba(237, 228, 211, .07),
    inset 0 -52px 68px -46px rgba(30, 30, 28, .9);
}

.media-frame--wide   { aspect-ratio: 16 / 9; }
.media-frame--std    { aspect-ratio: 4 / 3; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--tall   { aspect-ratio: 3 / 4; }

.media-frame__cap {
  display: block;
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .08em;
  line-height: 1.7;
  color: var(--c-on-dark-dim);
}
.section--paper .media-frame__cap { color: rgba(42, 39, 36, .62); }

/* ============================================================
   显现动效
   ============================================================ */
.js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity .42s var(--ease), transform .42s var(--ease);
}
.js [data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 1023px) {
  .nav-toggle { display: flex; }
  .site-header { height: var(--header-h); }
}

@media (max-width: 900px) {
  .meta-chip--wide { display: none; }
}

@media (max-width: 767px) {
  .brand-bar__meta { display: none; }
  .brand__note { display: none; }
  .brand__name { font-size: 17px; letter-spacing: .12em; }
  .brand__seal { width: 34px; height: 34px; font-size: 18px; }
  body { font-size: 15.5px; line-height: 1.88; }
  .rule-item { grid-template-columns: 34px 1fr; gap: 12px; }
  .timeline { padding-left: 18px; }
  .timeline__item::before { left: -23px; }
  .breadcrumb { font-size: 11.5px; }
  .fcol__k { width: 66px; font-size: 10.5px; }
}

@media (min-width: 768px) {
  .site-footer__inner { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .fcol--gate { grid-column: 1 / -1; }
}

@media (min-width: 1024px) {
  .site-nav {
    width: var(--rail-w);
    transform: none;
    visibility: visible;
    transition: none;
    box-shadow: none;
  }
  .site-nav__head { padding-inline: 26px; }
  .site-nav__link { padding-inline: 26px; }
  .site-nav__link::after { left: 26px; right: 26px; }
}

@media (min-width: 1100px) {
  .site-footer__inner {
    grid-template-columns: 1.15fr .95fr 1fr;
  }
  .fcol--gate { grid-column: auto; }
  .fcol + .fcol {
    padding-left: clamp(26px, 3vw, 44px);
    border-left: 1px solid var(--c-line);
  }
}

/* ============================================================
   减弱动效
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
    transition-delay: 0ms !important;
    scroll-behavior: auto !important;
  }
  .js [data-reveal] { opacity: 1; transform: none; }
  .btn--brass:hover { transform: none; }
  .site-nav__link:hover { padding-left: 26px; }
}