I am using CSS2.1 counters to apply numbers to men on the board in the implementation of a board game whose board diagrams use HTML and CSS, by doing something like:

```
.ply  {counter-increment:main;}
.move:before {content:counter(main);}

```

With HTML structured as

```
<ply>
  <move...>
  <ply>
    <move...>
  </ply>
</ply>

```

All this works fine, but I would like to **conditionally style the counter value** differently if it's two digits in length (squeeze the two digits together with a negative `letter-spacing`, for example). Any ideas about how to do this or workarounds?