#main {
	display:flex;
}

#left {
	top:40px;
	width:20%;
	/*background-color:green;*/
	margin-top:20px;
}

#right {
	width:20%;
	top:40px;
	/*background-color:green;*/
	margin-top:20px;
}

#middle {
	/*margin:0px 20px 0px 20px;*/
	padding: 0px 20px 0px 20px;
	top:-10px;
	overflow:auto;
	width:60%;   /* Note: This gets modified on resize in lesson.js */
}

.ad {
	margin:auto;
	width:164px;
}