title: Dummy img src without browser warnings
body: <p>I have constructed a lightbox for my website. For the purposes of this question, it consists of an img element, that is hidden by default using CSS.</p>
  
  <p>When a thumbnail image on my site is clicked, the src of the img element is overridden using javascript with the appropriate path, and the img is then made visible.</p>
  
  <p>My question is what do I set the img src to when the page is first loaded?
  If I leave the src blank, i get a browser warning.
  I would prefer not to load an actual image, as this uses bandwidth.
  I would prefer not to load a small transparent image of 1px, as this feels like a dirty hack.</p>
  
  <p>Do I have any other options?</p>