JSFiddle - React, Tailwind, and code Playground

HTML

<body>
  <script src="http://code.jquery.com/jquery-1.9.1.js"></script>

  <div class="block">

    <div id="hid">
      тут что-то вставляете
    </div>
  </div>
</body>

CSS

body {
  height: 1850px;
}

body {
  display: block;
  margin: 8px;
}

.block {
  display: block;
  margin: 8px;
  height: 200px;
  width: 250px
}

#hid {
  width: 150px;
  height: 50px;
  background: #FF0000;
  opacity: 0;
  position: fixed;
}

JavaScript

$(function() {
   var element = $("#hid"),
     display;
   $(window).scroll(function() {
     display = $(this).scrollTop() >= 200;
     display != element.css('opacity') && element.stop().animate({
       'opacity': display
     }, 500);
   });
 });