add a 3 4 x 12 red pencil tile trim around the window no casing install on all four sides of the window opening with clean mitered corners do not use bullnose schluter or any other trim profile pencil tile only the profile should be narrow rounded pencil trim not flat or square edge align the pencil tile precisely with the window edge and adjacent backsplash for a clean intentional frame match grout color to the surrounding tile keep all other materials and areas unchanged match or complement the existing backsplash material and grout color for a cohesive design keep the installation tight to the window edge with no visible gaps preserve all surrounding surfaces and finishes and do not modify any other areas of the space
