Combining Log In / Sign Up into a Single Tabbed Page

How to combine log in and sign up UI's into a single tabbed page.

Triggered from this discussion.

Demo

Use the Log In page on this site to see this in action.

Notes

Advanced

If you want to inject CSS into the IFRAME, here's the correct approach;

• https://stackoverflow.com/a/13959836
• https://redstapler.co/how-to-apply-css-to-iframe/

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