Hi The app is update now. You can take another look and see if this works for you?
If you don't like this new colour scheme and still think that choosing the theme is a great idea then I can make sure to add it in the future updates.
(The reason why I didn't want to add themes or other extra options was because I wanted the whole screen to be just a text area. In fact in next update I'm also going to remove the borders of this app, so it becomes a complete text box.)