Type size

I’ve just switched from Pal Nila to the Twenty Eleven theme, and I’m pretty pleased with the result.

However, there’s one thing I’d like to change: the size of the copy in the body of my posts seems quite big at 14pt.

Is there an easy way of converting the body copy to 12pt rather than 14pt that anyone can recommend please?

I don’t need to change the font itself, but I’m hoping there’s a good reliable plugin that does the job, or that there’s something in the code that’s suitably easy to edit as I’m a wuss about these things…

Many thanks,

Gavin