Hovering on the login/sign-up button to bring up the login modal is very annoying to use. At any time if you are not hovering on the modal it disappears!!!!! This even happens when selecting my username from the autofill suggestion on the username input; as soon as I hovered over that the modal disappeared. The validation error messaging is in a bad spot or at least behaves poorly; when a validation error message is displayed, setting focus to any input removes the error message causing the the height to shrink and if the mouse cursor happens to be at the bottom of the modal when that happens then the modal no longer receives the hover and disappears!

Then, if I want to go to a login page to avoid that whole mess, clicking on the login/signup button take me to the signup page where there is then a link to the login page. I get that you want to make this flow easy for to signup but if users are annoyed by the login modal then maybe have the signup form and login form side by side.