I’ve been a DIYr for 20 years. I’ve come across a problem with my kitchen backsplash. I want to tile the area between the countertop and overhead cabinets but the cabinets are crooked. The countertop is level. The over a five foot span, the wall measures 15″ high on the left and 14 1/2″ on the right. I want to use 7/8″ glass tile. Where do I start? Also let me say that this wall is directly in front of anyone entering the kitchen door, so I’m worried that everyone will notice. Am I too worried about 1/2 inch over this span…will it be noticeable?