/* stil for alle elementer */
* {		
  margin:0;
  padding:0;
}

body{margin:5px;}
nav, header, footer, aside, section, iframe {display:block;}
   
nav {
   width:925px;
   height:40px;
   background:#f3f3f3;
   border:1px solid #cccccc;
}

nav ul {  
    margin: 0 auto;  
    width: 900px;  
    list-style: none;  
} 

nav ul li {  
    float: left;  
} 

nav ul li a {  
    display: block; 
	margin-right: 10px;  
    width: 100px;  
    font-size: 18px;  
    line-height: 44px;  
    text-align: center;  
    text-decoration: none;  
    color: #000;  
}  

iframe {
	clear: both;
	width: 900px;
	height: 600px;

}