/* Style the topnav links */
.topnav a {
float: left;
display: block;
color: #f2f2f2;
text-align: center;
padding: 14px 16px;
text-decoration: none;
}
/* Change color on hover */
.topnav a:hover {
background-color: #EE22EE;
color: black;
}
/* Create two unequal columns that floats next to each other */
/* Left column */
.leftcolumn {
float: left;
width: 75%;
}
/* Right column */
.rightcolumn {
float: left;
width: 25%;
background-color: #601020;
padding-left: 20px;
}
Nothing really new here, just notice the float:left property being used on several of the classes