Sorry for the delayed response. We've been looking at
UI Kit's Off Canvas
Javascript library for a future release of SCLogin. Unfortunately, I haven't done enough investigation to let you know how easy it would be to implement. We have it on our to-do list to determine for an SCLogin release late this summer.
Until then, the Modal popup does have some responsive code built-in so that it resizes according to the user's browser width. It is not responsive in that fields will hide depending on the width or that the login form can show on desktop sizes whereas just the button (for the popup) will show on smaller windows. That's the best we have right now, but are always looking to improve things further.
We do appreciate your feedback and hopefully we'll have what you're looking for in a few months.
Thanks,
Alex