chage the opacity of bacvkground color code example
Example 1: css opacity background color
background: rgba(255, 255, 255, 0.25);
Example 2: background color with opacity
h1 {background-color:rgba(255,0,0,0.3);}
background: rgba(255, 255, 255, 0.25);
h1 {background-color:rgba(255,0,0,0.3);}