Fix regression: privateTabPaddingHorizontal

[luixxiul]

Addresses #8895

Auditors: @cezaraugusto

Test Plan:

1. new private tab paragraphs should be properly spaced

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[bsclifton]

Here before

and after

[bsclifton]

++! 😄

[cezaraugusto]

thanks but I think as we move more things to Aphrodite we should avoid using global styles for spacing and keep that file specific for future-friendly theming

[luixxiul]

For the sake of that I have added the prefix privateTab to the var :-)

[NejcZdovc]

I agree here with @cezaraugusto, because this will probably only used in private tab, we don't need it in global. We should keep global as slick as possible.

[luixxiul]

My thought on ^: #8340 (comment)