Hi SEO Experts, Font size in a site plays any role, which can be considered by the search engine. There is any specific size which the search engine loves.
Font size is considered - as sites with a font size that is far too small to read (in other words, spam) get penalized. Whether there is some 'ideal' font size, I really don't think so. Just concentrate on good semantic markup and you'll be fine (h1, h2, p, ul, b, em. . .) As long as you're font size is readable (I usually go with 11-12 for basic paragraph text), then the exact size is not going to make a difference. Your headings will obviously be bigger, but it is the h1/2/3 tag that Google loves, not the particular size itself.
YES!, Not only Font size, FONT COLOR also plays role in SEO, if your Font Color is unreadable by visitors(same color as of background) than there is a chance that you can get penalized.