如何将这三个小方框以同样大小放到大框中?
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>填充</title>
<style type="text/css">
#box1{
width:100px;
height:100px;
padding:10px;
border:1px solid red;
line-height:px;
position:absolute
}
#div1{
width:40%;
height:40%;
border:1px solid;
float:left;
margin:5% 5% 0 5%;
}
#div2{
width:40%;
height:40%;
border:1px solid;
float:right;
margin:5% 5% 5% 5%;
}
#div9{
width:40%;
height:40%;
border:1px solid;
position:absolute;
bottom:10%;
</style>
</head>
<body>
<div id="box1" >
<div id="div1"></div>
<div id="div2"></div>
<div id="div9" align="center">999</div>
</div>
</body>
</html>