I'm attempting to install a new vanity in a right-side corner, but upon trying today I discovered that the walls are not square, and the grout line of the mosaic tile on the floor is at a slight angle. So if I push the vanity flush against the walls, looking down using the grout lines as guide, the vanity looks crooked, and if I use the grout lines as a guide, then I have upwards of a 1 inch gap along the back or right side. There will be a side splash, but given the scenario, it'll be flush against the wall in the back right corner, but will angle out to 1 inch off, if I keep it aligned to the countertop. I'm at a loss for how to make this look right. Do I make the right-side flush, exposing the gap along the back and fill this will (a ton) of caulk (or molding), or make the back flush and fill behind the side splash with caulk? Any advice is greatly appreciated. Thanks!