header, footer, .center {
    text-align: center;
}
.gallery {
    max-width: 800px;
    margin: auto;
}
fieldset {
    text-align: left;
    padding: 5px;
    background-color: #eee;
}
.sec {
    max-width: 600px;
    margin: auto;
}
.sec2 {
    max-width: 400px;
    margin: auto;
}
.navbar {
    background-color: #333;
    overflow: hidden;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
}
.navbar a {
    float: left;
    display: block;
    color: #f2f2f2;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
    font-size: 17px;
}
.navbar a:hover {
    background-color: #ddd;
    color: black;
}
.navbar a.active {
    background-color: #04AA6D;
    color: white;
}