[3.0.x] Upgrade from 2.5.x might change vertical menus into a horizontal line display

[pepperstreet]

Warning! Vertical menus turn into a horizontal inline display! Due to Bootstrap5 flex property on UnorderedLists with class "nav". For instance all vertical menus in sidebars, bottom and footer positions.

Here is one way to solve it:
Go to Module Manager -> YourMenu module -> Advanced tab -> Menu Class Suffix
Enter " flex-column" as additional class value.
Remember to have a leading BLANK character.
This bootstrap utility class changes your flexbox display to a vertical direction!

Hope this helps.

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FYI – If you want to know more about other pre-defined Bootstrap5 classes:
https://getbootstrap.com/docs/5.1/utilities/