w3schools com background overlay code example

Example 1: 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;
}

Example 2: html overlay django

{% 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 %}