Which is better for full stack developing? Normal website design(html/css..)vs wordpress

now I'm developing a website using html/css/js/java~back end. I want to develop a whole website only by myself But my design skill is awful, it doesn't seem like responsive web design(location,size..) So I'm considering wordpress.

So the question is.. Using wordpress or developing my design skill which is better? By Considering Cost,speed,result.. Thanks for reading