/* ===== AB 面切换 ===== */

/* A 面：可滚动容器 */
#side-a {
  height: 100vh;
  overflow-y: auto;
  cursor: pointer;
}

#side-a img {
  display: block;
  width: 100%;
}

/* B 面：默认隐藏 */
#side-b {
  display: none;
}