Are you using Foundation Sans Condensed? If so, you should add some more letterspacing (tracking) to it -- say 10/1000 of an em -- and that would help your users' legibility issues tremendously. Going condensed allows more wordage, however, legibility is suffering. And to ask that users increase their browsers' font size by hitting "command+" is not a solution. Poor typography design is not the users' problem; it's a UI designer's job.