Wikipedia Viewer Project FeedBack

Hey guys I’m looking for feedback on how I can make my wikipedia app better looking, Ive seen quite a few of them and noticed some are extremely pretty looking. If you have any suggestions or just wanna let me know what you think please respond! <preferably with directions on what to do/ or resource> I wanna get better with CSS and HTML to make things more visually appealing but Theres so many books etc. which is best ? 2016 wise