def css(rgba):
    dark = (relative_luminance(rgba) < text_color_threshold)
    text_color = ('#f1f1f1' if dark else '#000000')
    return 'background-color: {b};color: {c};'.format(b=colors.rgb2hex(rgba), c=text_color)
def css(rgba):
    dark = (relative_luminance(rgba) < text_color_threshold)
    text_color = ('#f1f1f1' if dark else '#000000')
    return 'background-color: {b};color: {c};'.format(b=colors.rgb2hex(rgba), c=text_color)