This box uses opacity
This box has a background color with an alpha channel
.box1 { background-color: #000; color: #fff; opacity: .5; } .box2 { background-color: rgba(0,0,0,.5); color: #fff; }
<div class="wrapper"> <div class="box box1">This box uses opacity</div> <div class="box box2">This box has a background color with an alpha channel</div> </div>