A post Mathematical formulation of beam: get stress/strain from forces and momentum uses \overline{\overline{…}}
. The results below are mostly from Safari 16.1 on macOS 12.6.1, but casual experimentation suggests that, with one exception, they are not terribly browser-dependent.
Using HTML-CSS (Common HTML is almost identical):
Using Preview HTML:
Using SVG:
Using MathML on Safari:
Using MathML on Firefox 107.0.1:
The spacing of "MathML on Firefox" is the correct one (by comparing to a separate TeX installation). I am a bit surprised that the SVG spacing is incorrect, since I thought that just compiled it in an external process and just inserted an image of the resulting rendered equation.