How to add semi transparent background

You can set semi transparent background on a div or any html element by adding below style -

background-image: linear-gradient(to bottom, rgba(255, 255, 255, 0.5) 0%,rgba(255, 255, 255, 0.5) 100%), url(http://www.bestmanspeechestoasts.com/wp-content/themes/thesis/rotator/sample-4.jpg);


You can see the example here - http://codepen.io/deebujacob/pen/xVzRxw