Add <span class="section-number"> to section numbers in "globaltoc.html"

[mgeier]

Is your feature request related to a problem? Please describe.

It's not really a problem, but I (as a theme author) would like to style the section numbers in the sidebar separately from the section titles.

In other places, the section numbers are already enclosed in <span class="section-number"> and </span>, so I think it would make sense to also have this in the globaltoc.html (in the sidebar).

Describe the solution you'd like

I'd like the function toctree() (which is available inside the HTML templates) to add <span class="section-number"> and </span> around section numbers.

Describe alternatives you've considered

I guess an alternative would be to re-implement the whole toctree() function, but I think this would be a lot of work and I wouldn't even know where to start.

I think with the current version of the toctree() function it is not possible to select the section numbers with CSS.

Additional context

This would be the logical continuation of:

• Isolate section number in span tags for HTML output #6613
• Add get_secnumber to simplify add_secnumber #6632

[mgeier]

cc @yves-chevallier since you implemented #6632?