Using 2-parts buttons in page navigation bars

Hi, I’m new to WP but so far I’m liking it !

I did however run into a problem – I would like to use 2-parts buttons (left edge image is different from body/right edge) for sub page navigation bar. In order to do that it seems that I need to have

• titles wrapped in <span> tags. I did not find an alternative or official way to make menus produced by wp_list_pages(). So, I ended up modifying start_el function of Walker_Page class to do what I need.

  Is there an easier way to do what I need ? Because I will have to re-do my changes every time I update WP :/

  Thanks!

  PS. Here is a link to clarify what I’m talking about: https://www.reflectingclouds.com/?page_id=15