css overlay

#hero{
  background-image:url();
  background-size:cover;
  background-position:top center;
  position:relative;
}

#hero::after{
  content:'';
  position:absolute;
  left:0;
  top:0;
  height:100%;
  width:100%;
  background-color:black;
  opacity:0.7;
}

html, body {
  min-height: 100%;
}

body {
  position: relative; /* needed if you position the pseudo-element absolutely */
}

body:after {
  content: "";
  display: block;
  position: fixed; /* could also be absolute */ 
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  z-index: 10;
  background-color: rgba(0,0,0,0.2);
}

{% for instance in object_list %}
    <div align="center">
        <a href="#overlay{{ instance.pk }}">{{ instance.international_title }}</a>
    </div>
    <div id="overlay{{ instance.pk }}">
    <p>{{ instance.international_short_description }}<p>
    </div>
{% endfor %}

<div class="imagebg" data-overlay="5">
	<div class="background-image-holder">
		<img alt="background" src="img/file.jpg" />
	</div>
	<div class="container">
		Content
	</div>
</div>