Style and React organization feedback

I took Redux’s demo todo app built with react, and added styling, as well as responsiveness for mobile.

Demo link
Source code

I would like feedback on the style, but more importantly, I would like feedback on the organization of styles and css files for React projects. I added the styles/ folder, and the css files in there. I notice that I copied a lot of code, how would you approach refactoring to reuse styles, and also use media queries the right way.

Aside from styles, everything else given is from Redux’s demo. I hope to eventually make this into a forkable project that has a good starting point with styling as well as function.