article {
	background-color: #EEE;
	}
h1 {
	color: #AAC;
	font-size: 5.5vh;
	text-shadow: 0px 0px 0.6em #447, 0.02em 0.02em 0.15em #000;
	}

.sideblauw {
	top: 25vh;
	background-color: #66A;
}
.vakblauw {
	width: 400px;
	float: left;
	margin: 1em;
	padding: 1em;
	background-color: #337;
	border: solid 0.2em #AAC;
	color: #AAC;
}

#patcont {
	position: absolute;
	top: 50%;
	left: 50%;
	transform: translate(-50%, -50%);
	display: block;
	width: 600px;
	height: 600px;
	background-color: #FFF;
	}
#pata, #patb {
	position: absolute;
	width: 600px;
	height: 600px;
	background-image: url("math-images/random-600.gif");
	border: 1px solid #888;
	}

#nulbut {
	float: left;
	clear: both;
	}

button {
	float: left;
	margin: 10px 0px;
	padding: 3px 5px;
	color: #222;
	background-color: #CC5;
	border: 1px solid #222;
	border-radius: 5px;
	font-size: 1em;
	font-weight: bold;
	}