<head>
<style?type="text/css">
#main?{
position:relative;
margin:0;
padding:0;
width:900px;
border:1px?solid?black;
}
#main?#first?{
width:100%;
height:50px;
}
#main?#first?#first_1?{
width:50%;
float:right;
height:25px;
border:1px?solid?black;
}
#main?#second?{
width:100%;
height:50px;
border:1px?solid?red;
}
#main?#third?{
width:100%;
}
#main?#third?#third_1?{
width:30%;
float:left;
border:1px?solid?black;
}
#main?#third?#third_1?.third_1?{
width:100%;
border:1px?solid?blue;
height:50px;
margin-top:5px;
}
#main?#third?#third_2?{
width:65%;
float:right;
}
#main?#third?#third_2?.third_2?{
width:100%;
border:1px?solid?blue;
height:45px;
margin-top:5px;
}
</style>
</head>
<body>
<div?id="main">
<div?id="first">
<div?id="first_1"></div>
</div>
<div?id="second">
</div>
<div?id="third">
<div?id="third_1">
<div?id="third_1_1"?class="third_1"></div>
<div?id="third_1_2"?class="third_1"></div>
<div?id="third_1_3"?class="third_1"></div>
</div>
<div?id="third_2">
<div?id="third_2_1"?class="third_2"></div>
<div?id="third_2_2"?class="third_2"></div>
<div?id="third_2_2"?class="third_2"></div>
</div>
</div>
</div>
</body>
</html>