With this widget Fera will keep the add to cart button on the bottom of the screen on mobile
devices (500px or smaller width devices).
Keeping the Add To Cart button visible as the shopper is scrolling down the page on their mobile device
makes them more likely to click "add to cart".
By default, Fera will only keep the add to cart button sticky after the shopper has been seen for
more than 30 seconds (including previous site visits). This ensures that people coming from advertising campaigns have time to learn about the
product before asking them for the sale.