Sorry, your browser is broken beyond what I personally care to work around. The post is a mere <pre> tag with text in it, no further formatting applied. If even this breaks, anything might, and we could wrap the entire internet in <readmore>... Please check and repair your setup.
The 80 characters width is a conscious conservative choice, and the diagram renders correctly on my computer in Firefox, Opera, Konqueror, Internet Explorer, Safari, w3m, Links2, Lynx, Dillo, ... That's all the major browsers and a few obscure ones.
I had reports of some monospace fonts being not-so-monospaced for unicode linedrawing characters (while especially there, it really matters), so I uploaded the screenshot at http://juerd.nl/files/perlvalues.png. I try my best, but I have to draw a line with regards to how far I want to go, and adding <readmore> tags to hide the most important part of this work is well beyond that line.