Fix button alignment on error page

[srirambv]

Submitter Checklist:
Fixes:#11007

• 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).
• Tagged reviewers and labelled the pull request as needed.

Test Plan:
Visit https://expired.badssl.com/
Reduce the browser width to 478px
Ensure buttons are aligned properly as shown

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

[cezaraugusto]

yay looks way better, thanks sir!

[cezaraugusto]

per branch sha:

master 795f36a
0.20.x 1207731
0.19.x 03e000f

[luixxiul]

fyi this change affects every error page so let's not forget to do QA for the pages as well.