Apologies for the rant, but I'm frustrated...
Why on earth does Microsoft include Bootstrap 5 in Power Pages and then decimate it? It overrides most of the marvelous Bootstrap features with low quality Power Pages styles and attributes in theme.css, portalbasictheme.css and the positively horrible styles in preform.BootstrapV5.bundle.css.
Why doesn't the Power Pages Style Editor simply update existing Bootstrap CSS variables to customize the look and feel? Instead, it adds the unnecessary, convoluted portalbasictheme.css.
Or how Pages Editor inserts flexbox CSS inline, despite the fact that Bootstrap 5 is built on Flexbox and provides every class imaginable.
It is so frustrating to spend hours undoing all of this awful CSS, in order to let Bootstrap 5 perform using its own styles and variables.
I realize Microsoft want to provide a range of themes for low-code developers to utilize in Power Pages. But not everyone is a low-code developer. Every Power Pages solution we build at the organization where I work includes customized UI styling to suit our clients' brand guidelines and UI standards. I'm sure I am not the only frustrated Power Pages UI developer.
For goodness sake, I wish they would use the Bootstrap framework as it is intended, and not as a doormat on which to dump a load of custom CSS overusing the !important tag, ignoring CSS specificity.
Understandable for old Power Portals, but Power Pages should have moved past this years ago.