def css_style(format = :html, max_col = 80, max_row = nil, colors = Screen.default_css_colors)
			case format
			when :html
				Screen.css_style(colors, max_col, max_row)
			when :text
				''
			end
		end
def css_style(format = :html, max_col = 80, max_row = nil, colors = Screen.default_css_colors)
			case format
			when :html
				Screen.css_style(colors, max_col, max_row)
			when :text
				''
			end
		end
CSS stylelet to be used in <head>