Problem/Feature

This PR updates the padding-top of the MessageCard component from 17px to 20px so that it is consistent with other spacing.

Screenshots

Make sure the pull request:

[ ] Follows the established folder/file structure
[ ] Adds unit tests
[ ] If it is a refactor or change to an existing component, have you verified it won't break existing Cypress tests or have you updated them?
[ ] Did you verify some accessibility (a11y) basics?
[ ] Adds/updates stories. Guidelines
[ ] Adds/updates documentation (ie proptypes) Guidelines
[ ] Has it been tested in Help Scout's supported browsers?
[ ] Requests review from designer of the feature
[ ] Add label (bug? feature?)