Here is simple overlay div without using any gif, This can be applied over another div.
<style>
.loader {
position: relative;
border: 16px solid #f3f3f3;
border-radius: 50%;
border-top: 16px solid #3498db;
width: 70px;
height: 70px;
left:50%;
top:50%;
-webkit-animation: spin 2s linear infinite; /* Safari */
animation: spin 2s linear infinite;
}
#overlay{
position: absolute;
top:0px;
left:0px;
width: 100%;
height: 100%;
background: black;
opacity: .5;
}
.container{
position:relative;
height: 300px;
width: 200px;
border:1px solid
}
/* Safari */
@-webkit-keyframes spin {
0% { -webkit-transform: rotate(0deg); }
100% { -webkit-transform: rotate(360deg); }
}
@keyframes spin {
0% { transform: rotate(0deg); }
100% { transform: rotate(360deg); }
}
</style>
<h2>How To Create A Loader</h2>
<div class="container">
<h3>Overlay over this div</h3>
<div id="overlay">
<div class="loader"></div>
</div>
<div>