body{
				font: 24px helvetica;
				background: linen;
			}
			
			.father{
				min-height: 400px;
				margin: 0px;
				padding: 0px;
				display: flex;
				flex-flow: row;
			}
			.father > article{
				margin: 4px;
				padding: 5px;
				border-radius: 9pt;
				background: lightskyblue;
				flex: 4;
				order: 2;
			}
			.father > nav{
				margin: 4px;
				padding: 5px;
				border-radius: 9pt;
				background:lightgreen;
				flex: 1;
				order: 1;
			}
			.father > aside{
				margin: 4px;
				padding: 5px;
				border-radius: 9pt;
				background: lightgreen;
				flex: 1;
				order: 3;
			}
			header,footer{
				display: block;
				margin: 4px;
				padding: 5px;
				border-radius: 9pt;
				min-height: 80px;
				border: 3px solid lightsalmon;
				text-align: center;
			}
			
			
			 /* CSS 样式可以在这里添加 */
	        body {
	            font-family: Arial, sans-serif;
	        }
	        h1 {
	            text-align: center;
	        }
	        ul {
	            list-style-type: none;
	            padding: 0;
	            margin: 0 auto;
	            width: 300px;
	            text-align: center;
	        }
	        li {
	            margin-bottom: 20px;
	        }
	        .a2 {
	            display: block;
	            margin: 10px;
	            padding: 5px;
	            background-color: #4CAF50;
	            color: white;
	            text-decoration: none;
	            border-radius: 5px;
	        }
	        .a2:hover {
	            background-color: #45a049;
	        }
	        .a1 {
	            display: block;
	            padding: 10px;
	            background-color: #4CAF50;
	            color: white;
	            text-decoration: none;
	            border-radius: 5px;
	        }
	        .a1:hover {
	            background-color: #45a049;
	        }
	        @media all and (max-width: 640px) {
				.father {
					flex-flow: column;
				}
				.father > article,.father > nav,.father > aside{
					order: 0;
				}
				.father > aside,header,footer{
					min-height: 50px;
					max-height: 50px;
				}
				header h1{
					font-size: 20px;
				}
				footer p{
				    font-size: 17px;
				}
			
			}