/* using a different box-model */
* {
	box-sizing: border-box;
}

body {
	font: normal 16px Helvetica, Arial, sans-serif;
	margin-top: 60px; /* make up the space that nav-main used to take up */
}

/* when an elements children
are floated, use overflow: auto
to keep its height intact */
#nav-main {
	background-color: rgba(0,0,0,1);
	overflow: auto;
	position: fixed;
	top: 0;
	width: 100%;
	z-index: 100;
}
/* we have floated child LI's so
we need to use overflow: auto */
#nav-main ul {
	overflow: auto;
	margin: 0; /* get rid of user-agent CSS */
	padding: 0;
	list-style: none; /* get rid of discs */
}

#nav-main ul a {
	color: white;
	padding: 20px;
	display: block;
}
#nav-main ul a:hover {
	background-color: red;
}

#nav-main ul li {
	float: left;
}

article {
	border: 2px solid purple;
}

section {
	border: 1px solid green;
	padding: 20px;
	margin: 10px;
	position: relative;
}

span {
	border: 1px dotted blue;
	width: 100px;
	margin: 10px;
	padding: 10px;
	display: inline-block;
}

article,
aside {
	float: left;
	width: 50%;
}

footer {
	background-color: bisque;
	border: 2px solid blue;
	clear: both;
}

.title-moved {
	background-color: rgba(0,0,0,.5);
	border: 5px solid bisque;
	margin: 0;
	padding: 10px;
	position: absolute;
	top: 40px;
	left: 40px;
}