* {
    box-sizing: border-box;
}
body {
    margin: 0;
}
.header {
    background-color: #2196F3;
    color: white;
    text-align: center;
    padding: 15px;
}
.footer {
    background-color: #444;
    color: white;
    padding: 15px;
}
.topmenu {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: #777;
}
.topmenu li {
    float: left;
}
.topmenu li a {
    display: inline-block;
    color: white;
    text-align: center;
    padding: 16px;
    text-decoration: none;
}
.topmenu li a:hover {
    background-color: #222;
}
.topmenu li a.active {
    color: white;
    background-color: #4CAF50;
}
.column {
    float: left;
    padding: 15px;
}
.clearfix::after {
    content: "";
    clear: both;
    display: table;
}
.sidemenu {
    width: 25%;
}
.content {
    width: 75%;
}
.sidemenu ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
}
.sidemenu li a {
    margin-bottom: 4px;
    display: block;
    padding: 8px;
    background-color: #eee;
    text-decoration: none;
    color: #666;
}
.sidemenu li a:hover {
    background-color: #555;
    color: white;
}
.sidemenu li a.active {
    background-color: #008CBA;
    color: white;
}