.btn-1 { 
    box-shadow:1px 1px 8px rgba(245,245,245,1);
    transition: box-shadow .2s ease, transform .2s ease;
}

.btn-1:hover {
    -webkit-box-shadow: 0px 18px 35px -21px rgba(161, 163, 170, 1);
    -moz-box-shadow: 0px 18px 35px -21px rgba(161, 163, 170, 1);
    box-shadow: 0px 18px 35px -21px rgba(161, 163, 170, 1);
}