title: CSS background-position change on Y-Axis only
body: <p>Ok...so here is the problem.</p>
  
  <p>I have a CSS sprite image made up of ten(10) 25px x 25px icons laid out horizontally - thus resulting in a sprite image of 250px width.</p>
  
  <p>I am using these 25x25 images as thumbnails. I'm looking to have an opacity of 30% on these images in INITIAL view and when a user hovers over them the opacity needs to be 100% (1).</p>
  
  <p>So what I did was create a SECOND row of images with their opacity at 30% - so now I have a sprite image of 250px x 50px. The top 25px at 100% and the bottom 25px at 30%.</p>
  
  <p>I setup HTML as follows:</p>
  
  <pre><code>&lt;a href="largeimage1.jpg" class="thumb1"&gt;&lt;/a&gt;
  &lt;a href="largeimage2.jpg" class="thumb1"&gt;&lt;/a&gt;
  &lt;a href="largeimage2.jpg" class="thumb1"&gt;&lt;/a&gt;
  etc...
  </code></pre>
  
  <p>and the CSS:</p>
  
  <pre><code>a { display: block; float: left; width: 25px; height: 25px; background: url("250_x_50_spriteimage.jpg") 0 -25px no-repeat; }
  .thumb1 { background-position: 0 0; }
  .thumb2 { background-position: -25px 0; }
  .thumb3 { background-position: -50px 0; }
  a:hover { **background-position-y**: -25px; }
  </code></pre>
  
  <p>However, this doesn't appear to work unfortunately, as background-position-y is NOT supported in Firefox (or is not a standard, but is IE-specific).</p>
  
  <p>The idea is that we (only) want to SHIFT the sprite image UP (along y-axis) and leave the x-axis as is (or was set in the previous classes).</p>
  
  <p>If there is no simple CSS solution to this - can this opacity effect be done with JQUERY? So the thumbs would load at 30% opacity and would transition to 100% opacity when user hovers?</p>
  
  <p>Many thanks,</p>
  
  <p>M.</p>