.btn-garant a {
    background-image: linear-gradient(45deg , #4a86e0 40%, #24b9f4) !important;
    box-shadow: 0 8px 16px 0 rgba(22, 22, 22, 0.35) !important;
    background-position: 100% 0 !important;
    background-size: 200% 200% !important;
    transition: all 0.3s ease-in-out !important;
}

.btn-garant a:hover {
   box-shadow: 0 0 0 0 rgba(0,40,120,0);
   background-position: 0 0 !important;
}