$(function(){
		   
	$('.bloc').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+50},500);
			}else{
				elem.stop().animate({top:dTop-parent.offset().top},500);
			}
		});
		if(scrollY()>dTop){
			elem.stop().animate({top:scrollY()-parent.offset().top+50},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;
 }