js apply overlay color 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: make background overlay css
<div id="element-with-background-image">
<div id="color-overlay"></div>
...
</div>