docs: def update_style(self, mapping):
          """Use to update fill-color"""
          default = {
              "presentation:background-visible": "true",
              "presentation:background-objects-visible": "true",
              "draw:fill": "solid",
              "draw:fill-color": "#772953",
              "draw:fill-image-width": "0cm",
              "draw:fill-image-height": "0cm",
              "presentation:display-footer": "true",
              "presentation:display-page-number": "false",
              "presentation:display-date-time": "true",
          }
          default.update(mapping)
          style = PageStyle(**default)
          node = style.style_node()
          # add style to automatic-style
          self.preso._auto_styles.append(node)
          # update page style-name
          # found in ._page
          self._page.set(ns("draw", "style-name"), node.attrib[ns("style", "name")])