I don't know where to make this suggestion, so I try it here ... I want to suggest that Atlassian ship Confluence with a more readable font than Arial. I've just spend several days reading the customer's confluence and got tired of reading Arial. I suggest to make Source Sans Pro the new default font. It is not only more readable on different kinds of monitors but looks better, too. Open Sans is another good font.
For other users suffering from Arial: there is a nice Plug-in for Firefox and Chrome called "Stylish" that makes overrding CSS per site easy.