Thanh,
Sorry for the CSS troubles you're running into. It looks like there's a minor styling conflict between your template and our module. If you add the following style to your template, it should fix the overhang that you're seeing:
.sclogin .input-block-level {
width: 90%;
}
Obviously test some more and let us know if you run into any issues. Hopefully, everything goes smoothly for you.
Thanks,
Alex