Hi, Alexander,
You can specify the appearance of tables in an extra .css file and tell ox-reveal to use that .css file by specifying #+REVEAL_EXTRA_CSS. For example, say I have a
table.org and a table.css in the same directory. The contents of the two files are:
table.org---------------------------------------------
#+REVEAL_EXTRA_CSS: ./table.css
* Head1
The paragraph.
| Col0 | Col1 | Col2 |
|------+----------------+------|
| Cell | Something long | Cell |
| Cell | xx | Cell |
--------------------------------------------