background image and overlay code example
Example 1: background image overlay
html {
background:url(http://lorempixel.com/800/600/nature/2);
background-size:cover;
box-shadow:inset 0 0 0 2000px rgba(255, 0, 150, 0.3);
}
Example 2: make background overlay css
<div id="element-with-background-image">
<div id="color-overlay"></div>
...
</div>