css on hover element shifts down in firefox only

Question

http://webplio.com/web/app.php/register/

Hello, on that link, when hovering over the "add user" button, the + character seems to shift down on Firefox 29 nightly Linux by one pixel. On Chromium 32, it works fine. I've inspected the css and can't find anything obvious that would shift. Does anyone have an idea?

Answer 1

You have a class in there with a :before that is causing it from what I can see.

In .flaticon.solid:before remove the line-height: 1; and you should see the issue go away.