wb = xlsx_package.workbook
style_shout = wb.styles.add_style sz: 16, b: true, alignment: { horizontal: :center }
wb.add_worksheet(name: "Foobar") do |sheet|
  sheet.add_row ['Bad', 'spellers', 'of', 'the', 'world', '...']
  sheet.add_row ['Untie!']
  sheet.merge_cells("A2:E2")
  sheet["A2"].style = style_shout
end