Returns CSS classes for this style.

    This function will check all the styles specified style is based on and return their CSS classes.

    :Args:
      - document (:class:`ooxml.doc.Document`): Document object
      - style (:class:`ooxml.doc.Style`): Style object

    :Returns:
      String representing all the CSS classes for this element.

    >>> get_css_classes(doc, st)
    'header1 normal'

def get_css_classes(document, style):
    """Returns CSS classes for this style.

    This function will check all the styles specified style is based on and return their CSS classes.

    :Args:
      - document (:class:`ooxml.doc.Document`): Document object
      - style (:class:`ooxml.doc.Style`): Style object

    :Returns:
      String representing all the CSS classes for this element.

    >>> get_css_classes(doc, st)
    'header1 normal'
    """
    lst = [st.lower() for st in get_all_styles(document, style)[-1:]] + \
        ['{}-fontsize'.format(st.lower()) for st in get_all_styles(document, style)[-1:]]

    return ' '.join(lst)