Click Header Button > Show Lightbox

#1. Create a Page in Not Linked with 

• Name: Header Lightbox 
• URL: /header-lightbox

And then design your lightbox content layout

You will have this, here I added a List Section into Not Linked Page

#2. Install Lightbox Plugin

Download this Lightbox Plugin and open instructions.html file, you will get the code

After adding the lightbox code to Code Injection > Footer, you will see this

#3.  Edit Header button > Add this URL:  #lightbox_header-lightbox

All set.

When clicking the Header Button, you will have