#principal img.container-g{	
    float: left;
    max-width: 400px;
    max-height: 400px;
    margin: 0 40px 40px 0;
}
#principal img.container-d{	
    float: right;
    max-width: 400px;
    max-height: 400px;
    margin: 0 0 40px 40px;
}
#principal img.container-100{	
    max-width: 100% !important;
    margin: 20px !important;
    max-height: initial !important;
}