How do I affix the navigation arrows to the footer of the page?

Hi, the up and down navigation buttons (and the “Powered by Typeform” button) on my questionnaire, seen here, move out of view as you reduce the height of the browser window. 

How do I affix the those buttons to the bottom of the page, as seen starting on the second question of Guardian Bike’s Typeform questionnaire (note how, when you change the heigh of the browser window, those buttons remain in view).

In case it’s relevant, my questionnaire is embedded in Wix; I’m not sure what platform Guardian Bike uses.

Thanks!

Ian