main.css

.navDefault {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: #4a4a4f;
}

button {
    border: none;
    background-color: #0997d3;
    width: 150px;
    height: 50px;
    color: #fff;
    text-transform: uppercase;
    cursor: pointer;
}

.dropdownMenu{
    list-style: none;
    margin:0;
    padding: 0;
    position: absolute;
    left: 0;
    right: 0;
    top: 50px;
    z-index: -1;
    width: 150px;
    text-align: center;
    transform: translateY(-100%);
    transition: transform 0.5s ease-in-out;
}

.dropdownLink {
    text-decoration: none;
    display: block;
    background-color: #f9f9f9;
    color: #4a4a4f;
    padding: 10px 5px;
    transition: background-color .5s ease-in-out, color .5s ease-in-out;
}

.dropdownLink:hover {
    color: #fff;
    background-color: #a0a0a3;
}

.dropdown {
    width: 150px;
    position: relative;
}

.dropdown:hover button {
    background-color: #018ec5;
}

.dropdown:hover .dropdownMenu {
    transform: translateY(0);
    box-shadow: 0px 6px 10px 0px rgba(0, 0, 0, 0.2);
}