var police_em = 1;

$(document).ready
(		
	function()
	{
		$("#select_courses").change(function() {
			if ($(this).val() == "")
			{
				$(".table_performances").show();
			}
			else
			{
				$(".table_performances").hide();
				$("#table_performances_course" + $(this).val()).show();
			}
		});
		
		$("#police_plus").click(function(){		
			police_em += 0.1;
			$(".table_performances").css('font-size', police_em + 'em');
		});
	
		$("#police_moins").click(function(){
			police_em -= 0.1;
			
			if (police_em < 0.1)
				police_em = 0.1;
			
			$(".table_performances").css('font-size', police_em + 'em');
		});
	}
);