How do I create a nested tab?
To create nested tabs, you can create a new tab group, then click the button "Add HTML Code" and add the shortcode of another tab group.
What is tabbing in HTML?
HTML tabindex Attribute
The tabindex attribute specifies the tab order of an element (when the "tab" button is used for navigating). The tabindex attribute can be used on any HTML element (it will validate on any HTML element. However, it is not necessarily useful).