Agreed, I didn't use a capitalized letter on the password and the sign up failed. The error window appears outside of my viewport so I kept clicking the button and almost bounced.

I would generally do a page refresh on signup/error, that would avoid this as I'd know something happened rather than clicking submit 10 times. But that style of web development is no longer cool, so...

- I would smooth scroll the user up to where the error box is.

- A red border around the input that failed.