code: def _refresh(self):
          
          padding = self.height()
          css_base = """QLineEdit {{
                                   border: none;
                                   padding-right: {padding}px;
                                   }}
                     """
          css_oxygen = """QLineEdit {{background: transparent;
                                     border: none;
                                     padding-right: {padding}px;
                                     }}
                       """
          if self._application_style == 'oxygen':
              css_template = css_oxygen
          else:
              css_template = css_base
  
          css = css_template.format(padding=padding)
          self.setStyleSheet(css)
          self.update()
docs: After an application style change, the paintEvent updates the
          custom defined stylesheet.