Template:Center/styles.css

/* Basic alignment */
.wst-center {
	text-align: center;
	display:table; /* make this behave like an old style CENTER tag */
    margin:0 auto 0 auto;
}

/*
 * p-wrapping gives us a hard 7px bottom margin that is undesireable when
 * trying to align another element just below us (like a horizontal rule).
 * This is a workaround for that by simply forcing the margin to zero.
 */
.wst-center.wst-center-nomargin > p {
	margin-bottom: 0;
}