Perhaps for similar reasons that you posted about having a tabloid phone instead of an android phone?
Kidding aside, it happens to a lot of us. I believe our forum uses a slightly older software not optimized for mobile and your browser struggled to properly render the style sheet. This is just a guess, though. Are you able to try different browsers on your device?
Do you experience different results when using a different board style or skin? >> ucp.php?i=165
Does anyone else have insights?