JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://imakewebthings.com/jquery-waypoints/waypoints.js"></script>
<div id="share-bar" class="sticky-wrapper">This is share</div>
<div id="header">This is normal header</div>
<p>Thsi jnskfnlsdfdfgfg</p>
<p>Thsi jnskfnlsdfdfgfg</p><p>Thsi jnskfnlsdfdfgfg</p><p>Thsi jnskfnlsdfdfgfg</p><p>Thsi jnskfnlsdfdfgfg</p><p>Thsi jnskfnlsdfdfgfg</p><p>Thsi jnskfnlsdfdfgfg</p><p>Thsi jnskfnlsdfdfgfg</p>

CSS

#header {
    height: 55px;
    background-color: black;
    color: white;
    position: fixed;
    top: 0;
    width: 100%;
}
#share-bar {
    background: none repeat scroll 0 0 #FFFFFF;
    border-bottom: 1px solid #DDDDDD;
    box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.15);
    float: left;
    position: fixed;
    height: 55px;
    padding: 0;
    width: 100%;
    transition: all 0.2s ease 0s;
}
.sticky-wrapper { position:absolute; top:-55px; }
@media only screen and (min-width:400px) {    
.stuck {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 999;
    transition: all 0.2s ease 0s;
}    
}

JavaScript

$('#trigger').waypoint(function(){
    $( "#share-bar" ).toggleClass("stuck");
});