html{
    background-color: aqua;
}

body{
    width: 1000px;
    background-color: white;
}

header{
    height: 100px;
}

main{
    background-color: purple;
    /*display: flow-root;*/  overflow: hidden; 
}

aside{
    height: 300px;
    width: 400px;
    float: left;
    background-color: yellow;
}

div{
    height: 300px;
    width: 600px;
    float: left;
}

footer{
    height: 100px;
}