header{
                background-color: midnightblue;
                color: white;   
                padding: 20px;
            }
            nav{
                background-color: lightblue;
                padding: 20px;
            }
            main, aside {
                box-sizing: border-box;
                float: left;
                height: 400px;
                padding: 20px;
            }
            main{
                background-color: white;
                width: 70%;
            }
            aside{
                background-color: lightgray;
                width: 30%;
            }
            footer{
                clear: both;
                background-color: midnightblue;
                color: white;   
                padding: 20px;
                text-align: center;
            }