We just recently migrated from kentico 9 to kentico 12. In 12 we see the tabs layout is having an overflow issue --(no scroll bar) . What config change needs to be done to fix though the files in 9 and 12 are the same.
I suggest looking into the css of the overall tab layout. It's not a responsive-friendly set up so you will most likely need to make some changes with css and js.
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