Allow customization of main Buefy CSS styles, for falafel theme

tailbone/templates/themes/falafel/base.mako

@@ -153,8 +153,14 @@
 </%def>
 
 <%def name="buefy_styles()">
+  <% buefy_css = request.rattail_config.get('tailbone', 'theme.falafel.buefy_css') %>
+  % if buefy_css:
+      ## custom Buefy CSS
+      ${h.stylesheet_link(buefy_css)}
+  % else:
       ## Buefy 0.7.4
       ${h.stylesheet_link('https://unpkg.com/buefy@0.7.4/dist/buefy.min.css')}
+  % endif
 </%def>
 
 ## TODO: this is only being referenced by the progress template i think?