body {
    margin: 0;
}

.top-menu {
    display: flex;
    justify-content: center;   /* center menu */
    background-color: #800080;
}

.top-menu a {
    color: black;
    text-decoration: none;
    padding: 15px 20px;
    font-size: 16px;
}

.top-menu a:hover {
    background-color: #800080;
}