<style>

body{
text-align:center;
}

.main_container{
width:750;
height:500px;
margin-left:auto; margin-right:auto;
}

.header{
width:750px;
height:80px;
background-color:#e0e0e0;
border:1px solid #AD9482;
}

.nav{
width:200px;
height:350px;
float:left;
text-align:left;
background-color:#d0d0d0;
border:1px solid #AD9482;
overflow:auto;
}

.content{
width:550px;
height:350px;
float:left;
text-align:left;
background-color:#c0c0c0;
border:1px solid #AD9482;
overflow:auto;
}

html>body .header{
width:698px;
}

html>body .nav{
width:198px;
}

html>body .content{
width:498px;
}

.header_header{
margin-top:20px;
font-size:40px;
font-weight:bold
}

.nav_header{
font-size:30px;
font-weight:bold;
text-align:center;
}

.content_header{
font-size:40px;
font-weight:bold;
text-align:center;
}

</style>