Add Mobile Banner to Metafield

[jjacquelineftk]

Hi, I would like to add a metafield in my shopify that will allow me to add a version of a mobile banner for my collection pages. My current theme allows me to add a collection banner directly into the collection page - the hiccup is, the banner only looks good on desktop. 

This metafield will help me make sure that the banner looks good on both versions and will help me use it for all new and upcoming collection i make going forward - 

Any thoughts on how to execute this?

The shopify theme i'm using is Vantage 

The webiste is:https://www.favorthekind.com/

TIA!