Is the b byte indicator needed here? See plugin.py
Code:
def get_css_output_prefs(bk):
prefs = bk.getPrefs()
prefs.defaults['indent'] = "\t" #2 * ' '
prefs.defaults['indentClosingBrace'] = False
prefs.defaults['keepEmptyRules'] = True
prefs.defaults['omitLastSemicolon'] = False
prefs.defaults['omitLeadingZero'] = False
prefs.defaults['blankLinesAfterRules'] = 1 * b'\n'
prefs.defaults['formatUnknownRules'] = False
return prefs