Ah, I always do that too. The default sizes are not very good. Here's what I use typically:
/* course catalog font settings */
h3.coursename { font-size: 1.2em; }
h3.categoryname { font-size: 1.2em; }
.coursebox .info { font-size: 1.1em; }
.coursebox .teachers,
.coursebox .cost { font-size:0.9em; }
.coursebox .summary { font-size:0.9em; }