Unwanted horizontal scrollbar appears in FF and IE (jQuery 2.1.0)

[rbtbar]

Hi!

I was looking at your live example and this is just a little bug I've found:

I kept pressing one key for at least 5 seconds and suddenly a horizontal scrollbar appeared at the bottom of the frame...

Best Regards,
rb

[MartinF]

Thanks for reporting this issue.
The hidden mirror must be causing this.