Fixed Firefox Lesson Plan Overlap issue for all languages

[shail-mehta]

Fixed Lesson Plan Overlap Issue with Sidebar for All Languages in Firefox.

[shail-mehta]

Fixes https://github.com/WordPress/Learn/issues/1888

[jonathanbossenger]

Hi @shail-mehta thank you for your PR.

There seem to be some conflicts on this PR. Would you be able to refresh it, so that we can get it merged?

Thanks

[shail-mehta]

@jonathanbossenger Thanks for the feedback.

I have Resolved Conflicts issue & also refresh the PR With current trunk.

Can you please review it?

[ironnysh]

The redesign resolved #1888. This PR can be closed.

CC @jonathanbossenger