console 命令行工具 X clear
console
<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        div
        {
            width:100px;
            height:100px;
            background:blue;
            transition:all 2s;
        }

        div:hover
        {
            width:300px;
            height: 300px;
            background-color: yellow;
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>