I created a new system specific guide. WoD-nWoD How do I change the 'category' for it so that it is in the guides category?

Just add this to the bottom of the page: [ [Category:Guides] ] (without the spaces between the brackets). --Riley D. (talk) 14:26, 19 April 2013 (EDT)

changing font size from medium to small had no effect in Chrome

When in a campaign, following the link you posted for changing font size (W7 x64, Chrome Version 26.0.1410.64 m), did not have any effect on the roll20 UI. Everything remained in the same position and the same size, including the fonts/text.