[SoftAnnaLee]

Please correct me if I'm wrong, but I believe that 88x31 was done because Netscape distributed similar buttons for webmasters to include on their webpages if it was optimized for the Netscape browser. Buttons which were arbitrarily 88 pixels by 31 pixels. But then as those buttons propagated, other webmasters started creating other buttons that fit in with the original Netscape buttons; copying the same dimensions and styles.

Then it became an odd ad-hoc standard of that era of the internet, where you'd include 88x31 buttons because it was cool and popular. While others would be advertising their page based on how cool the buttons looked, and making them fit that standard 88x31 buttons so they were more likely to be included.