def get_style_fontsize(node):
    """Returns font size defined by this element.

    :Args:
      - node (:class:`ooxml.doc.Element`): Node element

    :Returns:
      Font size as int number or 0 if it is not defined

    """
    if hasattr(node, 'rpr'):
        if 'sz' in node.rpr:
            return int(node.rpr['sz']) / 2
    return 0
