$(function(){

	$('#menu_gauche').each(function(){
		var parent = $(this).parent();
		var dTop = $(this).offset().top;
		var elem = $(this);
		parent.css('position','relative');
		elem.css('position','relative');
		$(window).scroll(function(){
			if(scrollY()>dTop){
				elem.stop().animate({top:scrollY()-parent.offset().top},500)
			}else{
				elem.stop().animate({top:dTop-parent.offset().top},500)
			}
		});
		
	});

});


/**
 * Return the position of the top
 * */
function scrollY(){
			scrOfY = 0;
			if ( typeof( window.pageYOffset ) == 'number' ){
				//Netscape compliant
				scrOfY = window.pageYOffset;
			} else if( document.body && ( document.body.scrollTop )){
				//DOM compliant
				scrOfY = document.body.scrollTop;
			} else if( document.documentElement && ( document.documentElement.scrollTop )){
				//IE6 standards compliant mode
				scrOfY = document.documentElement.scrollTop;
			}
			return scrOfY;
}