don't wrap "[Hide explanation]" on small screens
don't wrap "[Hide explanation]" on small screens

Test Plan:
Before: {F368164}
After: {F368165}
Still looks fine on desktop: {F368150}

Reviewers: alex

Reviewed By: alex

Subscribers: jared

Differential Revision: https://phabricator.khanacademy.org/D26032

ariabuckles/perseus,ariabuckles/perseus,ariabuckles/perseus,ariabuckles/perseus,learningequality/perseus,learningequality/perseus