When u create an email Template, you must use inline styles with the template. Go through the following link. I think this will help you.
http://webdesign.tutsplus.com/articles/build-an-html-email-template-from-scratch--webdesign-12770
http://webdesign.tutsplus.com/tutorials/creating-a-future-proof-responsive-email-without-media-queries--cms-23919
