Remove use of * in CSS declarations. (mathjax/MathJax#3463)

[dpvc]

This PR removes the usage of * in CHTML's CSS selectors. Apparently, that is a performance issue in some cases, so these were made specific to the types of nodes that can be contained in the parent node. Some of the more complex ones are constructed from parts.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.77%. Comparing base (ec084b0) to head (6494d56).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1387   +/-   ##
========================================
  Coverage    86.76%   86.77%           
========================================
  Files          338      338           
  Lines        84387    84418   +31     
  Branches      4791     4796    +5     
========================================
+ Hits         73220    73251   +31     
+ Misses       11167    11144   -23     
- Partials         0       23   +23     

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[zorkow]

lgtm.

I did not know that * was a performance issue. But DuckAI agrees...