<div class="opacity-demo">
   <p style="color: rgba(0,0,0,1)">Opacity of 1
   </p>
   <p style="color: rgba(0,0,0,0.75)">Opacity of 0.75
   </p>
   <p style="color: rgba(0,0,0,0.5)">Opacity of 0.5
   </p>
   <p style="color: rgba(0,0,0,0.25)">Opacity of 0.25
   </p>
   <p style="color: rgba(0,0,0,0)">Opacity of 0
   </p>
 </div>

In style element (<style>) within head element:

.opacity-demo {
      background-image: url('images/satin.png');
      background-size: cover;
      color: white;
    }
    .opacity-demo p { font-size: 200%; font-weight: bold; font-family: helvetica,sans-serif;}