JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://www.christophelemaire.com/assets/js/bookmarkscroll.js"></script>
<div style="width:400px;margin:auto;">
		
        
        <div style="position:fixed;top:35%;z-index:1;left:50%;width:200px;margin-left:-100px;text-align:center;">
        <div class="" id="date"></div>
		<div class="" id="date2"></div>
		<div class="" id="date3"></div>
        </div>
        
					  <div style="position:relative;top:0;left:0;width:900px;margin-top:20px;margin-bottom:65px;" class="post">	
              		  <div class="description" style="display: none;">lundi</div>
                      <div class="description2" style="display: none;">16</div>
                      <div class="description3" style="display: none;">juin</div>
                      <img src="http://www.christophelemaire.com/images/uploads/news/_news/Sales-FW1314-intro-collecfemme.jpg" width="400" height="auto" class="big_image" />
					  </div>
				
                	  <div style="position:relative;top:0;left:0;width:900px;margin-top:20px;margin-bottom:65px;" class="post">	
              		  <div class="description" style="display: none;">Mardi</div>
                      <div class="description2" style="display: none;">17</div>
                      <div class="description3" style="display: none;">juin</div>
                      <img src="http://www.christophelemaire.com/images/uploads/news/_news/Sales-FW1314-allacarta.jpg" width="400" height="auto" class="big_image" />
				      </div>
                
                
                	  <div style="position:relative;top:0;left:0;width:900px;margin-top:20px;margin-bottom:65px;" class="post">	
              		  <div class="description" style="display: none;">Mercredi</div>
                      <div class="description2" style="display: none;">18</div>
                      <div class="description3" style="display: none;">juin</div>
                      <img src="http://www.christophelemaire.com/images/uploads/news/_news/Sales-FW1314-belt.jpg"...

CSS

.titre {
font-size: 15px;
font-weight: 100;
text-transform: uppercase;
text-align: center;
width: 900px;
}
.post {margin-bottom:0px;}
#date {
letter-spacing: 2px;
font-size: 14px;
line-height: 14px;
height: 20px;
font-family:normal,'LaPoliceBPRegular', serif;
text-transform:capitalize;
}
#date2 {
font-size: 68px;
line-height: 68px;
height: 60px;
font-family:'ExtraLemaire';
}
#date3 {
letter-spacing: 2px;
font-size: 16px;
line-height: 16px;
font-family:'SuisseBP';
text-transform: uppercase;
}

.day {letter-spacing: 5px;font-size: 15px;line-height: 15px;font-family:'ExtraLemaire'; z-index:1;width:220px;text-align:center;margin-top:15px;}
.day_number {font-size: 85px;line-height: 85px;font-family:'ExtraLemaire';z-index:1;width:220px;text-align:center;margin-top:15px;}
.month {letter-spacing: 5px;font-size: 20px;line-height:20px;font-family:'SuisseBP';text-transform: uppercase;z-index:1;width:220px;text-align:center;margin-top:5px}

JavaScript

var $toTop = $('#date,#date2,#date3');
$(document).scroll(function(){  
    $toTop.fadeIn();

    var scrollA = $(document).scrollTop();

    setTimeout(function(){
        if(scrollA == $(document).scrollTop()){
           $toTop.fadeOut();
        }
    }, 350);

})

var newDate="";
var newDate2="";
var newDate3="";
var exDate="";
var exDate2="";
var exDate3="";

$(window).load(function () {
    $(window).on("scroll resize", function () {
        var pos = $('#date').offset();
        $('.post').each(function () {
            if (pos.top >= $(this).offset().top && pos.top <= $(this).next().offset().top) {
                newDate=$(this).find('.description').text();
                newDate2=$(this).find('.description2').text();
                newDate3=$(this).find('.description3').text();
                if ((newDate != exDate)||(newDate2 != exDate2)||(newDate3 != exDate3))
                {
                    exDate=newDate;
                    exDate2=newDate2;
                    exDate3=newDate3;
                    $toTop.fadeOut(function(){
                        $('#date').html(newDate);
                        $('#date2').html(newDate2);
                        $('#date3').html(newDate3);
                        $toTop.fadeIn();}
                    );
                }
                return; //break the loop
            }
        });
    });

})