根据非空单元格填写每隔一行？

The first column in my spreadsheet comprises empty and non-empty cells. I'd like to take the first non-empty cell AND the immediate empty cells underneath it and fill their rows white. I then want to take the next non-empty cell and the immediate empty cells underneath it and fill their rows grey. I'd like to repeat this white-grey pattern throughout my spreadsheet. How can I do this without going through it manually?The first column in my spreadsheet comprises em