Fixes CSS basic import style when "css_usage" is enabled

[eduardomozart]

No description provided.

[Klap-in]

Hi @eduardomozart,
Nice to see your work on this plugin! Earlier, @lpaulsen93 was very active, at the moment not so much so far I can see.
Maybe it is interesting to contact him and ask if you could receive contributor rights.
That might making small improvements such as applying the php8 fixes a simpler effort, then you can simple merge such pull requests yourself.
For now I propose that you create pull requests as you do now, and that you use the “convert to draft” function to mark as long as you are working on it, or if you like to collect more commits first. If it is fine for merging, please mark it for review, and you can ask me to review it. I do not know that much of the internals of odt plugin and I have not a setup with this plugin, so please test yourself. Or, of course, don’t hesitate to ask in the PR, I observed other times some nice response was given by other users.
Also, I can store at some points the state as a release. For example if you feel the work on php8 support is quite complete, etc. Just ask :-)
Regards,
Gerrit

[eduardomozart]

The last commits from @lpaulsen93 on GitHub are dated from 2021, so I believe he isn't active on GitHub anymore. I try to contribute with DokuWiki and plug-in source code as much as I can because I use DokuWiki on a daily base since 2014 and I really appreciate the work that Andreas Gohr and others are making on it and I'm glad that I can make part of it. Since commit #296, the ODT plugin is pretty stable on PHP 8. There isn't errors anymore, and my commits since then only fixes Warnings that are visible only for users with display_errors PHP directive set to On, which most users didn't. I tested it's most features and it's working as expected when comparing with the ODT plug-in 2019-07-27 release (old stable, PHP7 release).
I believe my work is done about CSS basic style importing. I didn't use this feature but I found those warnings when testing it so I decided to fix it before someone reports problems with it.
I'll follow your advice on next PR's, converting them to draft first. Thank you for your feedback on my commits!