Transparent backgrounds
Base64, RGBA, plain image
by OmShiv
HTML
<div class="main">
<div class="box one"> BG Image as a 50% transparent PNG</div>
<div class="box two"> Base64 dataURI of above PNG</div>
<div class="box three"> RGBA with 0.5 opacity    <code>background: rgba(0,0,0, 0.5);</code> </div>
</div>
CSS
body {
color: yellow;
font-size: 15px;
font-family: "Cambria", Garamond, Helvetica, sans-serif;
}
.main, .box { padding: 20px; }
.main { background: url("http://subtlepatterns.com/patterns/arab_tile.png") 0 0; }
.box { margin-top: 10px; border: 1px solid #999; border-radius: 2px; }
.box.one { background-image: url("http://i.imgur.com/lPQm8Fy.png"); }
.box.two { background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAwAAAAMCAYAAABWdVznAAAACXBIWXMAAAsTAAALEwEAmpwYAAAAGElEQVR42mNkYGCoZyABMDGQCEY1jBQNAD+jAJe/Rx5TAAAAAElFTkSuQmCC); }
.box.three { background: rgba(0,0,0, 0.5); }
JavaScript
/*
IMPORTANT Note !!!!
JS fiddle will not load externally hosted images in the demo.
This is a common JSfiddle problem.
So you might have to open the following images in new tab,
and then reload this fiddle page
-- http://subtlepatterns.com/patterns/arab_tile.png
-- http://i.imgur.com/lPQm8Fy.png
*/