What do the shades on the IC's edge mean?
I asked a helpful staff member over at Digilent (makers of the Cmod A7 board) - and have just received this reply on their support forum:


  The colored pins are for bank identification. It is done for organizational reasons. And the bidirectional arrows next to the IC symbol are i/o pins. Hope this helps!


Edit: I goofed up with my original answer trying to paste from the datasheet on an iPad. Not only was my formatting wrong, but my answer was too. Sorry about that :(