Try it Live

<!DOCTYPE html> 
<html>
 <head>
   <style> 
     .textopa{
       display: inline-block;
       padding:15px;
	   max-width:100%;
       font-size:1.5em;
       font-family:georgia;}	
     .textopa.t1 {
       color: rgba(80, 160, 300, 0.2);
     }
     .textopa.t2 {
       color: rgba(80, 160, 300, 0.4);
     }
     .textopa.t3 {
       color: rgba(80, 160, 300, 0.6);
     }
     .textopa.t4 {
       color: rgba(80, 160, 300, 0.8);
     }
	 
     .textopa.t5 {
       color: rgba(80, 160, 300, 0.95);
     }	 
   </style>
 </head>
 <body>
   <h4> Example of Opacity in Modern Browsers </h4>
   <div class="textopa t1">Opacity 0.2 - 80% transparent means 20% opaque</div><br>
   <div class="textopa t2">Opacity 0.4 - 60% transparent means 40% opaque</div><br>
   <div class="textopa t3">Opacity 0.6 - 40% transparent means 60% opaque</div><br>
   <div class="textopa t4">Opacity 0.8 - 20% transparent means 80% opaque</div><br>
   <div class="textopa t5">Opacity 0.95 - 5% transparent means 95% opaque</div>
 </body>
</html>

​x
 
<!DOCTYPE html> 
<html>
 <head>
   <style> 
     .textopa{
       display: inline-block;
       padding:15px;
       max-width:100%;
       font-size:1.5em;
       font-family:georgia;}    
     .textopa.t1 {
       color: rgba(80, 160, 300, 0.2);
     }
     .textopa.t2 {
       color: rgba(80, 160, 300, 0.4);
     }
     .textopa.t3 {
       color: rgba(80, 160, 300, 0.6);
     }
     .textopa.t4 {
       color: rgba(80, 160, 300, 0.8);
     }
     
     .textopa.t5 {
       color: rgba(80, 160, 300, 0.95);
     }   
   </style>
 </head>
 <body>
   <h4> Example of Opacity in Modern Browsers </h4>
   <div class="textopa t1">Opacity 0.2 - 80% transparent means 20% opaque</div><br>
   <div class="textopa t2">Opacity 0.4 - 60% transparent means 40% opaque</div><br>
   <div class="textopa t3">Opacity 0.6 - 40% transparent means 60% opaque</div><br>
   <div class="textopa t4">Opacity 0.8 - 20% transparent means 80% opaque</div><br>
   <div class="textopa t5">Opacity 0.95 - 5% transparent means 95% opaque</div>
 </body>
</html>
​