Replace the leftover instances with .m-x-auto (and .d-block when necessary)
Closes #19665
Refs #19102
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flip things around again, no more base class, try out some new stuff to keep responsive flex grid working

Refs #18782
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So as to decrease the number of future inquiries about said edge case (which is already documented).
Refs #18304
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Things left:
1. clear the selection after copy
2. add messages for success and error

[skip sauce]

- clean out commented out code
- break apart homepage.scss into sub files by component
- rename a few files to reflect their new component names