Contact form submit button does not show up when screen resolution height <= 690px

[edwinjue]

Describe the bug
Contact form submit button does not show up when screen resolution height <= 690px. Need to account for fixed height footer, which is blocking the submit button when there is not enough vertical real-estate to display the entire contact form

To Reproduce
Steps to reproduce the behavior:

1. Go to https://dev.311-data.org/contact
2. Zoom into the page until the submit button disappears

Expected behavior
Should be able to scroll down to the submit button. Presently, contact form allows one to scroll down as far as the bottom of the message box

Screenshots

Desktop (please complete the following information):

• OS: Ubuntu
• Browser Chrome
• Version 105.0.5195.102 (Official Build) (64-bit)