$(document).ready(function(){

	function addClassSelected(a) {
		$(a).addClass('selected');
	}
	function removeClassSelected() {
		$('#nav ul.wpsc_top_level_categories li').removeClass('selected');
	}

	// Initialise first top-level category as selected
	$('#nav ul.wpsc_top_level_categories li:first-child').addClass('selected');

	// When a top-level category button is hovered...
	$('#nav ul.wpsc_top_level_categories > li').hover(function() {
		if (!$(this).hasClass("selected")) {
			// Make no top-level category selected
			removeClassSelected();
			// Then, make this top-level category selected
			addClassSelected(this);
		};
	});

});