$(function(){
		
	$('#fond_nuages').css({backgroundPosition: '0px 0px'});
	$('#fond_brume').css({backgroundPosition: '0px 0px'});
	
	$('#fond_nuages').animate({
		backgroundPosition:"(-10000px -2000px)"
	}, 240000, 'linear');
	
	$('#fond_brume').animate({
		backgroundPosition:"(-10000px -2000px)"
	}, 120000, 'linear');
	
});