Write something like
\max_X as an inline mathjax equation. The live preview will show it with the
X below the
max. This is the formatting resulting from a \displaystyle equation. In fact, when the card is actually seen (also simply through the preview via
ctrl-l), the equation is correctly displayed with the
X not below the
max, as inline equations usually look.
In other words, it seems like the live preview always shows equations with
\displaystyle, even when this is not the case.