Using a sticky add to cart button for my product pages for phone only

[VinUp]

Hello everyone,

I would love to use a sticky 'add to cart' button for my product pages for my shopify store: www.vinup.nl/en

Ideally it would be great if the 'add to cart' button would appear at the bottom of the first section of the product page as soon as a customer visits it on their phone, dissappear when the usual 'add to cart' button is visable. And then appear again as soon as a customer scrolls past the default 'add to cart' button. So that the button is basically always visable for the customer.

The theme i am using is Origin. 

Thanks in advance!

[MayaDesigns]

Maybe you can try one of those mobile menu app (example).

I am not exactly sure to what level can the behaviour be customized to your need, but you should be able to get to something you have described.