I have a problem with JS popup which appears when I click

Hello!

I have a problem with JS popup which appears when I click "[Delete]" in a cart - the text in the popup is not readable (see the 1st screenshot). When I'm directly on my billing website (without your pluging which makes the integration) it's ok (see the 2nd screenshot). May be this is encoding problem or what do you think?

Regards, Eugene.