title: What could cause the same browser on different PCs to render the same HTML differently?
body: <p>I'm stumped. A client and I are both running Firefox 3.0.12 on XP machines. We view the same page in the same browser on different machines and have different results. Note: All IE browsers are consistent on both of machines, and my FF 3.5.1 is consistent with my FF 3.0.12. (He does not have FF 3.5.x installed to compare with).</p>
  
  <p>There is a 1 pixel difference that causes his header div <strong>(all images, no text)</strong> to wrap. Mine is fine. If I expand his header by 1 px (via Firebug css editing), it works.</p>
  
  <p><strong>So my question is what other variables are there that affect rendering??</strong> </p>
  
  <p>I'm trying to think "outside the box" because it seems that it should work exactly the same. </p>
  
  <p>We cleared the browser cache. I did a diff on the HTML source, and other than a javascript datetime stamp and a javascript tracking code var, the sources are identical.</p>
  
  <p>I know this question would be helpful with source, but my client specifically does not want this page live on the internet yet. Also I verified the issue via a webex session. At first, I couldn't believe that we would have different results.</p>
  
  <p><strong>Anyone else come across something like this before? What should I check out / debug next?</strong></p>
  
  <p><strong>Edit:</strong> There are a lot of suggestions pointing to fonts, but the header uses only images. Well, that's not completely true, there are divs that are part of a collapsible menu, but all of that is set to <code>display:none</code> for initially rendering, so I'm thinking that it's something else. </p>
  
  <p><strong>Edit 2:</strong> I've changed all sorts of fonts and sizes (both the system default font settings and within Firefox) on my computer to try to replicate the problem. I changed the rendering style (standard vs. clear type). Nada. <strong>The problem is almost definitely not font related.</strong> I'll have to see if I can get some more access to the client's computer to replicate the problem.</p>