No, I don't think so, SEO more concern with unique and quality content not for other stuff like font, color, size.
hi, font styles is not effect on SEO but SEO for good tactics is like - H1 > H6 is used in the content of website.
I have red somewhere that the color and text size of the font do matters. An example is making your font Bold or italized will matter in the SEO.
I don not think font or design will effect on SEO, also if the site is slow by bad design will effect
Generally font doesn't play an important role in SEO. However, if you are molding it for applying some black hat techniques like hidden text etc, then it could affect your website.
I think font style doesn't matter in SEO, as font style gives appearance to content only, but if you use font style for black hat purpose then it will definitely hurt your site....
color does'nt matters in SEO ,only making font bold or heading matters. And these things are important only when you are looking for keyword density
Color makes matter in SEO if you are using the font color same as of background to make the text hidden...