Corrected [CSS3BACKGROUND] -> [CSS3BG]

Author: bert-github

css3-images/Overview.src.html

@@ -186,7 +186,7 @@ <h2 id="#image">Image Fallbacks: the ''image()'' notation</h2>
       <pre>background-image: image(wavy.svg, 'wavy.png' 150dpi, "wavy.gif"  or blue);</pre>
     <p>The 'background-image' property specifies that dimensionless images
        must stretch to cover the entire background positioning area
-       [[CSS3BACKGROUND]], so if none of the specified images can be displayed
+       [[CSS3BG]], so if none of the specified images can be displayed
        the background will be painted blue. As with any image, this fallback
        will be painted over the 'background-color' (if any).
   </div>