.nav-buttons {
    position: fixed;
    left: 50%;
    transform: translateX(-50%);
}
@media screen and (max-width:992px) and (min-width: 577px) {
    .nav-buttons {
        position: relative !important;
        left: 0;
        transform: none;
    }
}

@media screen and (max-width: 720px) and (min-width: 481px) {
    .nav-buttons-first-button {
        margin-left: 20px;
    }
}