add overlay over backgrounnd image css code example
Example 1: background overlay css
html {
min-height:100%;
background:linear-gradient(0deg, rgba(255, 0, 150, 0.3), rgba(255, 0, 150, 0.3)), url(http://lorempixel.com/800/600/nature/2);
background-size:cover;
}
Example 2: 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);
}