body{
    width:1280px;
    margin: 0 auto;
}
h1,h2{
    text-align:center;
}
ul {
    list-style-type: none;
    margin: 0 auto;
    padding: 0;
    overflow: hidden;
    background-color: #333;
}

li {
    float: left;
}

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

li a:hover:not(.active) {
    background-color: #111;
}

.active {
    background-color: #4CAF50;
}
footer {
    position: absolute;
    bottom: 0;
    width: 1280px;
    height: 8.5rem;
    overflow: hidden;
    background-color: #333;
}