If it works for you here on Meta but it’s not working on your site, then it might be a font issue. However, like I said we don’t support Opera.
The best thing I can recommend is to try safe-mode on your site
your.site.com/safe-mode
and see if the issue persists. If the issue does not occur in safe mode, then you might need to check your theme / css / font since it might be causing the problem on Opera.