create a CSS stylesheet in a Text document, using DOCX.stylemap(), above.

def stylesheet(self, fn=None, unit=CSS.rem, pt_per_em=None, decimals=2, font_factor=1/2., space_factor=1/20.):
        """create a CSS stylesheet in a Text document, using DOCX.stylemap(), above."""
        styles = self.stylemap(definitions=True, all=True, cache=False)
        used_styles = self.stylemap(definitions=False, all=False, cache=False)
        css = CSS(fn=fn or (self.fn and self.fn.replace('.docx', '.css')) or None)
        if pt_per_em is None:
            # use the size of the "Normal" font as 1.0em by definition
            normal = [styles[k] for k in styles if styles[k].name=='Normal'][0]
            if normal.properties.get('sz') is not None:
                pt_per_em = float(normal.properties['sz'].val) * font_factor
            else:
                pt_per_em = 12.
        for styleName in used_styles:
            style = styles[styleName]
            sel = self.selector(style)
            css.styles[sel] = self.style_properties(styles, styleName, unit=unit, pt_per_em=pt_per_em, decimals=decimals, font_factor=font_factor, space_factor=space_factor)
            LOG.debug("%s %r" % (sel, css.styles[sel]))

        return css