img {
width: 70%;
margin-right: 15%;
margin-left: 15%;	
}


#container {
background-color: darkblue;
/* width and margins and padding left,right can't exeec 100 % */
width: 80%;
margin-left: 10%;
margin-top: 40px;

height: 1600px;
float: left;	
margin-bottom: 600px;
}


.menubox {
background-color: darkblue;
color: silver;
width: 10%;
height: 20px;
margin-left: 10%;
margin-top: 5px;
float: left;
}

/* special selctor  both: menubox hover*/
.menubox:hover{
background-color: yellow;
}

#menuholderhover {
background-color: lightblue;
width: 60%;
height: 30px;
margin-left: 20%;
margin-top: 0px;
float: left;
/* advanced css */
position: fixed;
z-index: 0;
}


.contentbox {
background-color: silver;
/*height: 300px;*/


width: 30%;
padding: 3%;
margin-left: 8%;
margin-top: 10px;
float: left;
}




body {
	margin: 0px;
	padding: 0px;
	background-color: black;
}