Try it Live

​x
 
<!DOCTYPE html> 
<html>
  <head>
    <style> 
      body {
       background: rgba(194,0,55,0.4);
      }
    </style>
  </head>
  <body>
    <h2>Background color is containing opacity. Remove 0.4 in background style property to see orginal color</h2>
  </body>
</html>
​