body, td, th, textarea, h1, h2, h3, h4, h5, h6 {
font-family:"Lucida Grande",Verdana,Helvetica,sans-serif;
}

Change existing sample styles to whatever family you wish, then put between <style></style> tags and save in your Ads & Custom HTML area in the Head and Meta Data box

CSS to change the font family across your SocialGO network

CSS