def to_css
      css_parts = []
      background = [flattened[:background_color].to_s,flattened[:background].to_s].join(" ").strip
      css_parts.push("background: #{background}") if background and background != ""
      css_parts.push("color: #{flattened[:color].to_s}") if flattened[:color]
      css_parts.join("; ")
    end
def to_css
      css_parts = []
      background = [flattened[:background_color].to_s,flattened[:background].to_s].join(" ").strip
      css_parts.push("background: #{background}") if background and background != ""
      css_parts.push("color: #{flattened[:color].to_s}") if flattened[:color]
      css_parts.join("; ")
    end
Returns a string that can be used as inline cell styling (e.g. `<td style="<%=cell.format.to_css%>"><%=cell%></td>`)
 @return String very basic CSS styling string