/* 侧边栏、mid‑col容器全部透明，让body背景透出来 */
.left‑col {
  background-color: transparent !important;
}
.mid‑col {
  background: transparent !important;
}
#container {
  background: transparent !important;
}
/* 全局背景，首页+文章详情页统一，不会拉伸变形 */
body {
  background-image: url("/img/bj.jpg");
  background-size: cover;
  background-position: center center;
  background-repeat: no-repeat;
  background-attachment: fixed;
  min-height: 100vh;
}