flexible-footer-columns.css

.footer-widget-area {
	border: 1px solid #000; /* For better visualization, not necessary */
	float: left;
}

/* One column */
.footer-widget-area:nth-child(1):nth-last-child(1) {
	float: none; /* No need for one column to float */
	width: 100%; /* Not necessary, but better illustrates technique */
}

/* Two columns */
.footer-widget-area:nth-child(1):nth-last-child(2),
.footer-widget-area:nth-child(2):nth-last-child(1) {
	width: 50%;
}

/* Three columns */
.footer-widget-area:nth-child(1):nth-last-child(3),
.footer-widget-area:nth-child(2):nth-last-child(2),
.footer-widget-area:nth-child(3):nth-last-child(1) {
	width: 33.3333%;
}