* {
	box-sizing: border-box;
}
body {
    font-family: Arial, Helvetica, sans-serif;
    margin: 0;
}
header {
    background-image: url('stars.jpg');
    background-size: cover; 
    background-position: center;
    padding: 30px;
    text-align: center;
    font-size: 35px;
    color: white;
}
#tablewrapper { 
	display: table; 
width: 100%;}
nav {
    width: 30%;
    background: darkcyan;
    padding: 20px;
	color: darkcyan;
	display: table-cell;
}
nav ul {
    list-style-type: none;
    padding: 0;
}
nav a {
    text-decoration: none;
    color: #000;
}
nav a:hover {
    text-decoration: underline;
    color: #ffcc00;
}
article {
    flex: 1;
    padding: 20px;
    background-color: white;
} 
#three-columns {
    display: flex;
	justify-content: space-between;}
#column {
    flex: 1;
    margin: 0 10px;
    background-color: #e9e9e9;
    padding: 15px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
	margin: 20px 0; 
	background-color: lightblue;
}
footer {
    background-color: darkblue;
    padding: 10px;
    text-align: center;
    color: white;
}