Overlay not properly positioned

[socsieng]

Describe the bug A clear and concise description of what the bug is.

Overlay isn't properly positioned for https://form-troubleshooter-forms.web.app/login/login-nested.html

Probably related to https://github.com/GoogleChromeLabs/form-troubleshooter/commit/c49d4d16c57ba9cf30e845dde862a9c67183ec4f