Navbar breaks on subtheme due to equal ordering of rules for navbar

Problem/Motivation

Following an upgrade of drupal 10.3 to 10.4 we are now seeing some weird behaviour with ordering of css files that results in drop down of the main navigation becoming unusable.

This seems to depend on the naming of the subtheme. I think as in attempting to solve this I created a subtheme with the name 'test' and with duplicate code I get the appropriate behaviour.

My guess here is that the problem here is that there is a change in ordering from inherited to alphabetical. Because the theme in question starts with 'ba' - which is before bo - we have problems.

Steps to reproduce

Using Drupal 10.3 or lower create a dxpr subtheme using the script. Ensure the name starts with 'ba'
Set up a main menu with at least 1 level of drop down - make sure there are enough root level menu items to fill the screen width.

Menu should work.
Upgrade to drupal 10.4 - menu breaks.
Note I've switched between 10.3 and 10.4 on the same site and seeing the breakage without resaving the dxpr settings form.

Inspecting the css we see that bootstrap 5 is applying display: flex to .navbar and dxpr-theme-header is applying display:block to dxpr_theme_header. I thinks this is being built out of the settings form.

Note I've exported the settings from a working subtheme copied them and imported them into a broke theme (then run drush cex and manually updated until the settings that don't work on import get set.)

Proposed resolution

We should probably add an additional weighting so that the rule generated out of the settings gets one more css weighting - then it will take preceedence over bootstrap. This removes issues with ordering.

Remaining tasks

User interface changes

API changes

Data model changes