/*.btn-prev {
    color: white;
    border: 2px solid white;
    -webkit-transition-duration: 0.4s; 
    transition-duration: 0.4s;
}
.btn-prev:hover {
    box-shadow: 2px 2px 2px white;
    color: white
}*/
.btn-prev {
    color: black;
    border: 2px solid black;
    -webkit-transition-duration: 0.4s; /* Safari */
    transition-duration: 0.4s;
}
.btn-prev:hover {
    box-shadow: 2px 2px 2px black;
    color: black
}