Hi Arash and Jihuan,

>>>>> Arash Esbati <arash@gnu.org> writes:
>> That doesn't reproduce for me. I attach two screenshots; one for raw
>> appearance, another for preview-latex appearance:

> I can reproduce this.  I tried this .tex file:

Ah, indeed. Now I can see the difference in the preview-latex. All
(most?) math expressions in Theorem environnment are in bold. I'm very
sorry, Jihuan.