body {
    font-family: Calibri, Verdana, Helvetica, Arial;
    font-size: 12pt;
}

* {
    box-sizing: border-box;
}

.left {
    display: block;
    text-align: left;
}

.center {
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 80%;
}

header {
    line-height: 5px;
    padding: 5px;
    background-color: #404040;
    color: white;
}

nav {
    width: 100%;
    font-size: 12pt;
}

    nav ul {
        list-style-type: none;
        margin: 0;
        padding: 0;
        overflow: hidden;
        text-align: left;
    }

    nav li {
        float: left;
    }

    nav li a {
        display: block;
        color: blue;
        padding: 8px 16px;
        text-decoration: none;
    }

li a.active {
    color: #404040;
    font-weight: bold;
}


li a:hover {
    background-color: #555;
    color: white;
}

article {
    padding: 10px;
    width: 100%;
    background-color: white;
}

footer {
    background-color: white;
    padding: 10px;
    text-align: center;
    border-width: thin;
    border-top: solid;
    border-top-color: lightgrey;
}

/* Responsive layout - makes the two columns/boxes stack on top of each other instead of next to each other, on small screens */
@media (max-width: 600px) {
    nav, article {
        width: 100%;
        height: auto;
    }
}