console 命令行工具 X clear

console

<html>
 
	<body>
		<div class="grandFather">
			<div class="father">
				<div class="son"></div>
			</div>
		</div>
	</body>
</html>

	.grandFather
			{ 
				width:300px;
				height:500px;
				background-color:blue;
				margin:10px 0 0 0 ;
                padding: 12px;
                 border: 2px solid red;
                  position:relative
			}
			.father
			{top: 10px;
                width:100px;
                height:400px;
				background-color:black;
                margin:10px 0 0 0;
                padding:0px 0 0 0;
                border: 2px solid red;
               
			}
			.son
			{
				width:50px;
				height:50px;
				background-color:green;
                position:absolute;
                top:30px;
			}