Es ist klar welches deine Muttersprache ist.
But instead of opening a lightbox, why not just creating a page and link to it?
So whenever the user tries to open a certain page, he/she will be navigated to the → BREAK-PAGE. So all you would have to do is to change the links to the BREAK-PAGE.
User clicks a button to enter a page, and normaly he assumes to be navigate to the right page, but instead will be navigated to the BREA-PAGE, with the SORRY-MESSAGE.
Of course there also would be a way, by using the LIGHTBOX.
For example one idea which comes into my mind, would be to use …
—> onVieportEnter on your ‘#page1’ element.
Everytime when you enter the viewport of the page, an event triggers and opens again the lightbox. That means → you click the lightbox away (closing) → entering the viewport of the page, it triggers an event → opening the LIGHTBOX again.
If this does not work…
Generating a code, which checks every SECOND, if the LIGHBOX is openend or not (when clicking onto the ENTER-BUTTON) —> setIntervall();
This are just some first ideas which comes into my mind when regarding your issue.
Surely there are even more possibilities.