If the question is about layout computation then CSS Grid layout (and ideally <table> layout) is a typical LP task [1].

And there are known way of solving these things, e.g. simplex methods or Cassowary constraint solver (CCS)[2] will work.

In fact flexbox layout is a particular case of LP task and also can be solved by CCS efficiently.

[1] https://en.wikipedia.org/wiki/Linear_programming [2] https://en.wikipedia.org/wiki/Cassowary_(software)