#squareA {
    height: 500px;
    width: 865px;
    background-color: red;
    position: absolute;
    top: 0px;
    right: ;
    bottom: ;
    left: 0px;
}
#squareB {
    height: 500px;
    width: 865px;
    background-color: darkblue;
    position: absolute;
    top: 0px;
    right: 0px;
    bottom: ;
    left: ;
}
#squareC {
    height: 500px;
    width: 865px;
    background-color: red;
    position: absolute;
    top: ;
    right: 0px;
    bottom: 0px;
    left: ;
}
#squareD {
    height: 500px;
    width: 865px;
    background-color: darkblue;
    position: absolute;
    top: ;
    right: ;
    bottom: 0px;
    left: 0px;
}
#squareE {
    height: 50px;
    width: 300px;
    background-color: red;
    position: absolute;
    top: 0px;
    right: 290px;
    bottom: ;
    left: ;
}
#squareF {
    height: 50px;
    width: 300px;
    background-color: red;
    position: absolute;
    top: ;
    right: ;
    bottom: 0px;
    left: 290px;
}