How do I get my blog font back to the default color after I've changed the color of the text in a blog?

When I posted a blog, I accidently changed the text color of the font to black (where as the default color is a shade of blue). I'm not sure if there's a way to get the text color of that specific blog back to the default color. Can anyone help me?

I think that at the end of the blog theres a default button where you can hit it and it goes to your original font color......