Google Sheets Conditional Formatting Needed

I need to create alternating colors for rows 19 to 28 and specifically for cells F29, F30, F31, and F32 using fill colors #F2F2F2 which is light gray and #F2F2F2 which is white. There will be a lot of hiding and unhiding of rows for this range and I need a solution that always displays alternating colors despite frequent hiding and unhiding of rows. Can anyone help me with setting up a conditional formatting rule that automatically alternates the row colors, regardless of row insertion, deletion, or hiding? https://docs.google.com/spreadsheets/d/1SwqtiYIrZdO8p6YOxKsOx5MTgE3qQwAajTKIImYWHmE/edit#gid=1503373653