div设置宽度后，为什么里面的元素会超出div的边界
<style type="text/css">
#div1{
width:200px;
height:200px;
border:2px red solid;
position:relative;
top:50px;
left:100px;
}
</style>
</head>
<body>
<div id="div1"><p>wocaoniaksdljaskjldhauisfakjsfgashfgakjsdajkshdjahsdklhalkjsd</p></div>
</body>
</html>
