Style
So why use CSS?
Improved readability
- Establishing font families and faces.
- Defining font sizes in EMs.
- Proper Kerning and Leading.
- Simplified margins, spacing and indenting.
A highly detailed article on readability is avilable on the W3C's site.
Also, a note on font sizing. Owen Briggs created 264 screenshots for us to reference.
Lastly, SURL's Usability News has A Comparison of Popular Online Fonts. Note, they are popular for a reason. Follow the article up by reading So, What Size and Type of Font Should I Use on My Website?