Unfortunate that it seems at least for FF4 there is an interaction between the <pre> and <code> tags around the actual haskell such that about the last 1/2 of long lines are cut off.
It did finally get me to install the readability addon though.
You can often use the menu View -> Page Style -> No Style to fix these sorts of problem. On Windows it's a quick Alt-V-Y-N and then an Alt-V-Y-B to turn styling back on.
It did finally get me to install the readability addon though.