a "plug and play" lightbox script that utilizes local storage to make sure that it never shows up again (until cookies are cleared) after the user clicks on the button.
you can put this on every single page to make sure that your viewers absolutely see your warning.
put this in your <body> or it won't work.
edit lightBoxCss and lightBoxHtml to your liking.
to test this, it's as simple as Inspect, go to Console, then type in localStorage.clear(); then Run the script.