Feedback: try crash my JavaScript calculator

I’m complete JavaScript calculator and need your feedback. Some bugs can alive. Can someone test it?
Or just engoy and tell me what you think about design.
click and _blank to codepan
Thanks for your attention, /username/.

The moving background is distracting other than that the calculator works fine:)

I think you’re right about the background, but let it remain as the twist of the design.

Thanks for feedback! It’s help me, really.

0.7 + 0.1 should be 0.8, but your calculator displays 0.7999999999999999

Surprise…I try fix it tomorrow; a hunch tells me it’ll be fun.

Thank you for this bug. I know, but forgot this feature binary numbers. I fix it, look at if you have time.
Solution is not elegant, but work (I hope).