body {
    background-color: lightblue;
}

ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: #333;
    position: -webkit-sticky; /* Safari */
    position: sticky;
    top: 0;
    width: 100%;
}

li {
    float: left;
    border-right: 1px solid #ff0000;
}

li a {
    display: block;
    color: #26ff00;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

li a:hover {
    background-color: #000000;
}

.active {
    background-color: #00c37c;
}