*{box-sizing:border-box;}

header{
	height: 100px;
	padding: 20px;
	text-align: center;
	background-color: beige;
}

nav {
    background-color:yellow;
    margin:0px;
}

nav ul{
	list-style-type: none;
	background-color: yellow;
	text-align: center;
	padding: 10px;
	margin: 0px;
}

nav ul li{
	display: inline;
	padding: 5px 15px; 
}

nav ul li a{
	color: blue;
	text-decoration: none;
}

nav ul li a:hover{
	background-color: lightyellow;
}

.row{margin: 0px; height: 400px;}

.row:after{
	display: table;
	content: " ";
	clear: both;
}

.left{
	float: left;
	height:100%;
	width: 60%;
	padding: 5px 20px;
	background-color: gray;
}

.right{
	float: left;
	height:100%;
	width: 40%;
	padding: 5px 20px;
	background-color: tan;
}

footer{
	text-align: center;
	padding: 20px;
	background-color: lightblue;
}

a.clickableImg { 
    margin-left:20%;
    text-align:center;
}
img.thumbnail {
    width:40%;
    height:auto;
}
img.thumbnail:hover {
    width:43%;
}