.center {
    display: block;
    margin-left: auto;
    margin-right: auto;
}

body {
    max-width: 960pt;
    margin: auto;
    border: 6pt solid white;
}

header h1 {
    font-size:  300%;
    text-align: center;
}

#s1, #s2, #s3, main {
    font-size: 100%;
    width: 232pt;
    height: 300pt;
    float: left;
    border: 2pt solid white;
    margin: 2pt;
}

#s2 ul, #s3 ul {
	margin-left: 15pt;
	padding-left: 0;
}


main {
    margin-right: 0;
}

section, footer { 
    font-size: 100%;
    clear: left; 
}

#nav_menu ul { 	
    list-style-type: none; 
	margin: 0;
	padding: 0;
	position: relative;
}
#nav_menu ul li { 
    float: left;
} 
#nav_menu ul li a {
    text-align: center;
    display: block;
    width: 240pt;
    padding: 8pt 0;   
    text-decoration: none;
    background-color: blue;
    color: white;
    font-weight: bold;
    border-right: 0pt solid white; 
}
#nav_menu ul li a.lastitem { 
	border-right: none;
} 

/*      */