code: func CssProviderNew() (*CssProvider, error) {
  	c := C.gtk_css_provider_new()
  	if c == nil {
  		return nil, nilPtrErr
  	}
  
  	return wrapCssProvider(glib.Take(unsafe.Pointer(c))), nil
  }
docs: // CssProviderNew is a wrapper around gtk_css_provider_new().