Fix a lightbox in every page

I´m designing a side menu with a lightbox that will stay present all the time in every page instead of being opened by clicking a button. If I show the lightbox in every page it´ll only load in the first one. If I make one for each page it´ll only load the first time I open each page. Is there a way to make it fixed always in every page as if it was a vertical header? Also, I would need for it to stay put even if someone presses ESC or if the click outside the lightbox.

Thanks!
Eugenia

Instead of using a lightbox, use a regular box and pin it to the screen (this will work on desktop only and on mobile devices).

P.S. you can automatically open a lightbox on every page, but you should consider if that’s what you want (I don’t think it a very good user experience in the case you described).

I thought about that, the problem is that a box won´t resize it´s height according to the screen, unless there is a way to do this with code. Is there?

Got an answer for this? I basically need a menu which size fits the screen height. Thanks