Feature/mobile styling

[olipyskoty]

Contributing to Twilio

All third party contributors acknowledge that any contributions they provide will be made under the same open source license that the open source project is provided under.

• [x] I acknowledge that all my contributions will be made under the project's license.

Pull Request Details

JIRA link(s):

N/A

Description

This PR adds mobile designs to the app so that it can be used on mobile devices.

Burndown

Before review

• [ ] Updated CHANGELOG.md if necessary
• [ ] Added unit tests if necessary
• [ ] Updated affected documentation
• [ ] Verified locally with npm test
• [ ] Manually sanity tested running locally
• [ ] Included screenshot as PR comment (if needed)
• [x] Ready for review

Before merge

• [ ] Got one or more +1s
• [ ] Re-tested if necessary