I solved the problem. It was not related to Javascript. There was a CSS conflict with my theme, which I solved by overriding one of your styles by adding this to my site’s custom CSS window:
.tml * {
box-sizing: content-box !important;
}
That overrides the conflicting style:
.tml * {
box-sizing: border-box;
}
that appears in theme-my-login.css. The look of the fields is a bit different, but I don’t mind. Thanks!