set opacity of background color css code example
Example 1: css opacity background color
background: rgba(255, 255, 255, 0.25);
Example 2: background color opacity
rgba(51, 170, 51, .1) /* 10% opaque green */
rgba(51, 170, 51, .4) /* 40% opaque green */
rgba(51, 170, 51, .7) /* 70% opaque green */
rgba(51, 170, 51, 1) /* full opaque green */