====== Center a block element ======

''text-align'' only centers the text inside the block. To center an entire
block element, we must make it smaller than the parent (otherwise,
what's the point?) then tell the browser to adjust the left and right
margins accordingly.

<code css>
div.center {
	width: 80%;
	margin-left: auto;
	margin-right: auto;
/* -or-
	margin: 0 auto;
*/
}
</code>