p標簽如果是div標簽的話，就是另個一個效果了，這樣容易引起誤會的。
<!DOCTYPE html>
<html>
<head>
?? ?<meta charset="UTF-8">
?? ?<title>Document</title>
?? ?<style>
?? ??? ?#box1{height: 50px;background-color: red;float: left;}
?? ??? ?#box2{height: 100px;background-color: blue;float:right;}
?? ??? ?#box3{height:150px;width:300px;background-color: black;}
?? ?</style>
</head>
<body>
?? ?<div id="box1">盒子1</div>
?? ?<div id="box2">盒子2</div>
?? ?<div id="box3">盒子3</div>
?? ?<p>fjkdlsjfkjslkjfdlskjdflkjsdklfjsljkdlljkdlsjfkjslkjfdlskjdflkjsdklfjsl</p>
?? ?<p>fjkdlsjfkjslkjfdlskjdflkjsdklfjsljkdlljkdlsjfkjslkjfdlskjdflkjsdklfjsl</p>
</body>
</html>
2015-12-21
一般清浮動，常用是給父級加上clearfix，一共有8中方法可以請浮動，和標簽沒有多少關系的。