Fix layout issues with explanations inside explanations
Fix layout issues with explanations inside explanations

Summary:
https://app.asana.com/0/27216215224639/198728636241830

New animation:
{F582148}

Old animation:
{F582149}

Test Plan:
View /math/multivariable-calculus/multivariable-derivatives/partial-derivative-and-gradient-articles/a/directional-derivatives-going-deeper
At the bottom open [A seemingly unrelated puzzle to help with the intuition]
Open the "Answer"
Everything should look ok

Reviewers: leo, oliver

Reviewed By: oliver

Subscribers: jared

Differential Revision: https://phabricator.khanacademy.org/D31525

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