def page_margins
      @page_margins ||= PageMargins.new
      yield @page_margins if block_given?
      @page_margins
    end
Page margins for printing the worksheet.
@example
wb = Axlsx::Package.new.workbook
# using options when creating the worksheet.
ws = wb.add_worksheet :page_margins => {:left => 1.9, :header => 0.1}

# use the set method of the page_margins object
ws.page_margins.set(:bottom => 3, :footer => 0.7)

# set page margins in a block
ws.page_margins do |margins|
margins.right = 6
margins.top = 0.2
end
@see PageMargins#initialize
@return [PageMargins]