div {
float: left;
clear: both;
}

body {
margin: 0px;
padding: 0px;
}

img{
float: left;
width:70%;
margin-left: 25%;
margin-right: 25%;
margin-top: 5%;
}

#container{
background-color: yellow;
width: 100%;
}

.headbox{
width:60%;
margin-left:20%;
margin-right: 20%; 

height:100px;
background-color: orange;
color:black;
text-align:center;
font-size:30pt;
text-decoration: bold;
}

.sidemenubar{
width:18%;
min-width: 180px;
background-color:blue;
text-align: center;
padding-bottom: 40px;
clear: none;
margin-top: 30px;	
}

.menubox{
color:lightgreen;
background-color:blue;
text-align:center;
font-size: 40px;
width:50%;
margin-left:4px;
margin-top: 4px;   
}

.maintextbox{
width:55%;
padding: 5%;
background-color:black;
color: white;
font-size: 35px;
text-align: center;
clear:none;
margin-left:10%;
margin-top: 30px;
}

.physics{
background-color: brown;
color:white;
font-size:40px;
text-align: center;
clear:none;
margin-left: 10%;
margin-top: 30px;
padding:5%;
width:50%%;
}

.chemistry{
background-color:silver;
color:white;
font-size:40px;
text-align: center;
clear: none;
margin-left: 10%;
margin-top: 20px;
padding:5%;
width:40%;
}

.biology{
background-color:green ;
color:white;
font-size: 35px;
text-align: center;
clear:none;
margin-left: 15%;
margin-top: 25px;
padding:2%;
width:60%;
}