left/right padding in equationgroups incompatible with line breaking (only visible with MathJax)

[xworld21]

MathJax 4 re-introduced line breaking, at last. However, this exposes an odd choice in the LaTeXML CSS which effectively breaks pages rendered with MathJax.

This simple example

\usepackage{amsmath}
\begin{align*}
  a + b + c + d + e + f &= f + e + d + c + b + a
\end{align*}

when converted to MathML and passed through MathJax 4 becomes

This is because LaTeXML generates a table with two extra columns 'padleft/padright' of size 50% on both sides. Now that MathJax allows line breaking, the cells containing the maths will often shrink to the minimum possible size to account for those columns.

What is the purpose of padleft/padright? If it is only centering the table, I suggest switching to auto margins or even a flex wrapper, neither of which would have this problem (and they are also better for screen readers).

[dginev]

What is the purpose of padleft/padright?

At the time they were introduced, this was one of the few available reliable cross-browser techniques for centering an equation while allowing the ability to optionally add labels in the margins.

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Two brief thoughts:

A modern approach to achieve this could also use CSS Grid.

Also, if we end up making changes, the MathJax line-breaking logic would be somewhat poor motivation. We should independently investigate a line-breaking polyfill for the browser's native MathML rendering that works well with LaTeXML. And if that requires changes, it would be more in line with the MathML focus of LaTeXML.

[xworld21]

A modern approach to achieve this could also use CSS Grid.

Let me add: one should also think carefully about whether table semantics is appropriate or not. Thinking of screen reader use, is tabular navigation appropriate for equation groups? I am guessing no, because e.g. when I use align* I am always writing content that is meant to be read left-to-right, one line at a time; being interrupted by 'column 1', 'column 2', etc is distracting. (Another plausible rule of thumb is that if you cannot think of sensible table headers, then it should not be a table). But for instance the screen reader should probably flag the start of a new line as it may be a new equation altogether, and maybe that does not happen with grid. Many things to consider here, and not enough experience with screen readers...

allowing the ability to optionally add labels in the margins

Thanks, I needed that pointer. It's not just centering! I need a moderately urgent workaround for BookML, because MathJax 4 brings too many improvements to pass it up, and I should really get rid of those tables; I might have prototype suggestions soon-ish (say in a month).

Summarising: I guess the issue should rather be 'modernize equation groups' to account for line breaking, accessibility, and modern CSS.