Better to place it right into tyl template - thankyoulike_tyl_counter_forumdisplay_thread
<span title="{$lang->tyl_firstpost_tyl_count_forumdisplay_thread}" class="tyl_counter">{$thread['tyls']}</span>
if ($thread['tyls'] < 1) {
echo '<span title="{$lang->tyl_firstpost_tyl_count_forumdisplay_thread}" class="tyl_counter" style="border: 1px solid green;">{$thread['tyls']}</span>';
} else ...
<span title="{$lang->tyl_firstpost_tyl_count_forumdisplay_thread}" class="tyl_counter">{$thread['tyls']}</span>
if ($thread['tyls'] < 1) {
echo '<span title="{$lang->tyl_firstpost_tyl_count_forumdisplay_thread}" class="tyl_counter" style="border: 1px solid green;">{$thread['tyls']}</span>';
} else ...
[MyBB 1.8 Czech translation] [MyBB 1.8 plugins]: Prune old PMs + optimize DB plugin --- Thank you/like system