/* ==========================================================================
   首页背景：康威生命游戏底纹 (life-bg.css)
   —— 与 js/life-bg.js 配套，仅在首页加载。

   默认启用（<html class="life-mode">）：页面仍然是主题原本的白底浅色样式，
   只是在所有内容下面垫了一层「纯白底 + #e9eddf 像素点」的淡色底纹；
   右下角按钮可以切回不带底纹的纯白背景。
   ========================================================================== */

/* ---------- 背景画布：固定铺满视口，位于所有内容之下 ---------- */
.life-canvas {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: block;
  z-index: -1;
  background: #ffffff;
  pointer-events: none;
}

html:not(.life-mode) .life-canvas {
  display: none;
}

/* ---------- 浅色底纹：不需要改主题变量，只把 body 变透明让画布透出来 ---------- */
html.life-mode {
  background: #ffffff;
}

/* body 必须透明，否则会盖住 z-index:-1 的画布 */
html.life-mode body {
  background: transparent;
}

/* 顶栏/页脚原本是不透明白，稍微放透明一点，底纹会若隐若现 */
html.life-mode .site-header {
  background: rgba(255, 255, 255, 0.86);
}

html.life-mode .site-footer {
  background: rgba(255, 255, 255, 0.86);
}

/* 相册区与精选卡片原本铺了底色，放开让底纹透过去 */
html.life-mode .home-gallery {
  background: transparent;
}

html.life-mode .featured-card {
  background: transparent;
}

/* ---------- 右下角的“背景”设置按钮（浅色页面上用深色胶囊） ---------- */
.bg-toggle {
  position: fixed;
  right: 22px;
  bottom: 22px;
  z-index: 90;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 16px;
  border: 1px solid rgba(255, 255, 255, 0.3);
  border-radius: 999px;
  background: rgba(26, 26, 26, 0.78);
  color: #f7f7f7;
  font-family: var(--font-sans, sans-serif);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 1.2px;
  line-height: 1;
  cursor: pointer;
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.18);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: background-color 0.15s ease, border-color 0.15s ease, transform 0.15s ease;
}

.bg-toggle:hover {
  background: rgba(26, 26, 26, 0.95);
  border-color: rgba(255, 255, 255, 0.6);
  transform: translateY(-1px);
}

.bg-toggle:focus-visible {
  outline: 2px solid #1a1a1a;
  outline-offset: 2px;
}

.bg-toggle-icon {
  display: inline-flex;
  align-items: center;
}

.bg-toggle svg {
  display: block;
  width: 14px;
  height: 14px;
}

.bg-toggle[data-mode='white'] svg {
  opacity: 0.75;
}

/* ---------- 窄屏适配 ---------- */
@media (max-width: 768px) {
  .bg-toggle {
    right: 12px;
    bottom: 12px;
    padding: 8px 13px;
    font-size: 0.68rem;
    letter-spacing: 0.8px;
  }
}

@media print {
  .bg-toggle,
  .life-canvas {
    display: none !important;
  }
}