'css template will later allow to choose a colormap'

def _css(self):

    css = [self._css_template]
    for i in range(255):
        color = (u'FFFF%02x' % int((255 / (1 + (i / 10.0)))))
        css.append(('.cython.score-%d    {background-color:    #%s;}' % (i, color)))
    try:
        from pygments.formatters import HtmlFormatter
    except ImportError:
        pass
    else:
        css.append(HtmlFormatter().get_style_defs('.cython'))
    return '\n'.join(css)
