Quick suggestion. You should probably edit any "invisible" elements down to 1 by 1. Sorry for the small, nearly pointless request.
~Edit~
Oh yeah, I forgot. The blue slider border looks kind of odd with the combo colors. Maybe you could color the track blue to match? Or at least make the border black to match with the hitcircles.
~Edit~
Oh yeah, I forgot. The blue slider border looks kind of odd with the combo colors. Maybe you could color the track blue to match? Or at least make the border black to match with the hitcircles.