实例：全屏背景切换动画
技术栈：HTML+CSS+JS
效果：
源码：
【HTML】
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>全屏背景切换动画</title>
<link rel="stylesheet" href="226.css">
</head>
<body>
<div class="container">
<div>
<img id="img-0" class="active" src="https://picsum.photos/1920/1080?random=1" />
<img id="img-1" src="https://picsum.photos/1920/1080?random=2" />
</div>
<div
