.upleft {
    height:50px;
    width:50px;
    position:absolute;
    background-color: #000FFF;
    top:0;
    left:0;
   
}

.upright {
    height:50px;
    width:50px;
    position:absolute;
    background-color: #000FFF;
    top:0;
    right:0;
   
}

.downright {
    height:50px;
    width:50px;
    position:absolute;
    background-color: #000FFF;
    bottom:0;
    right:0;
   
}

.downleft {
    height:50px;
    width:50px;
    position:absolute;
    background-color: #000FFF;
    bottom:0;
    left:0;
   
}