.menu {
    display: flex;
}

.menu-item {
    position: relative;
}

.menu a {
    display: block;
    background: blue;
    color: white;
    padding: 15px 25px;
    text-decoration: none;
    border-right: 2px solid white;
}

.menu a:hover {
    background: oldlace;
    color: black;
}

.submenu {
    display: none;
    top: 100%;
    left: 0;
    background: black;
    width: 200px;
}

.submenu a {
    border-bottom: 1px solid white;
}

.dropdown:hover .submenu {
    display: block;
}