Everything from the text, buttons, and info cards. They are all so large, it' like having my browser set to 300% zoom. You could easily fit more content from each skill/tab on the screen by just reducing the size of everything.
The side bar could benefit with a hide category option, again even just reducing the size of the text you could probably fit every skill on screen without needing a scrollbar.
Having an option to make notifications appear in a different location as well as disappear quicker would be very welcome too.
With much love