@media (min-width: 992px){
    .navbar-expand-lg .navbar-nav .dropdown-menu {
        background: #fdfdfd;
    }
}
@media (min-width: 1px) and (max-width: 576px) {
    h1{
        font-size: 1.8rem;
        padding-bottom: 1em;
    }
    h1,h2,h3,h4{
        text-align:center;
    }
}