Markdown previewer project review in React

I have completed my markdown previewer project:

I would very happy about any feedback you could provide to improve it further.

I also I have a question about the structure of my React-Redux app logic. I am keeping user input in a Redux state and then transforming it with marked in render method of preview element. Is this the correct place to do such modifications ? Is it maybe better to do the transformations in handler and action functions?