左右浮动 <br /> #nav{height:30px;border:1px solid red;}<br /> #content{border:1px solid black;}<br /> #footer{position:absolute;bottom:0px;height: 20px;border:1px solid red;width: 100%;}<br /> sdfs sdfsd sdfs sdflksdjflskdjflksdjflskdjflksjdlfjsldkfjld 样式: