Fix horizontal scrollbar height, closes #5728

[jayphelps]

See #5728 for issue details.

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The contributing docs say:

All pull requests should be merged into the next branch.

But if I set that as the PR target it appears next is 13 commits behind master, so it wants to include those commits too. Is that instruction out of date maybe?

[jlukic]

Probably should target this with :horizontal pseudo class for clarity, although i dont believe fixed height would affect vertical scrollbars, it might be funny for the rule to apply.

[jlukic]

@jayphelps this is in the release going out now, 2.2.14

Thanks for your patience. New updates will be quicker in the new year.