I used to set the zoom level at 110% to increase the forum's small font size to a comfortable level (Firefox remembers it), but I've since migrated to a user CSS (using an extension called "Stylus", don't know if Safari has a similar one). Here's the bit that increases the font sizes:
Code:
/* For the REAPER 5 forum theme */
body { font-size: 15px; }
td, th, p, li { font-size: 15px; }
.smallfont { font-size: 12px; }
.thead { font-size: 11px; }
textarea, .bginput { font-size: 15px; }
.navbar { font-size: 14px !important; }