the back button is on a red background which isn’t visible because of the light 
Hey! Not bad! Here are some things which I, personally, believe would improve your interface:
-
Add a blur behind the UI. This can be done by adding, from a LocalScript, a blur to
Game.Lighting. Doing so would blur the UI only for the player who has the UI, and not for other players. Your text would then stand out better against the background, which is made of complicated shapes (which makes it harder to read) -
Add a space on the side to match the bottom, in the ‘overview’ box. The space from the text to the border on all sides should be roughly equal to provide a sense of balance
-
Where possible, text with equal emphasis should have equal size. The ability description and the overview description should be equal size.
Good start; keep it up my friend!