Mobile browser's bottom bar covers Texter buttons

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Describe the bug

The bottom bar of mobile browsers covers the Texter buttons rendering Spoke unusable on that device.

To Reproduce
Steps to reproduce the behavior:

1. Begin texter workflow on mobile
2. See that browser bottom bar covers buttons

Expected behavior

Texter workflow buttons should always be visible.

Screenshots

N/A

Smartphone (please complete the following information):

No specific version

Additional context

Related: #445