Untitled

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <script>
	function zmien_kwadrat()
	{
	var k=document.getElementById("kwadrat");
	if (k.style.backgroundColor=="red")
	{
	with (k.style)
	{
	backgroundColor="yellow";
	width="200px";
	height="200px";
	}
	}
	else
	{
	with (k.style)
	{
	backgroundColor="red";
	width="400px";
	height="400px";
	}
	}
	}
	</script>
</head>
<body>
 <div id="kwadrat"
 style="background-color:red; width:400px; height:400px;" onclick="zmien_kwadrat();"
 </div>
</body>
</html>