Toggling a Mobile Design
It's up to you whether you choose to have a mobile design or not. You can enable or disable this function within the design editor by using the button highlighted below.
How Will it Display?
If you decide to use an optional mobile design, your certificate design will be replaced by the mobile one - which has a ratio closer to phone screens - only on small screens:
If you choose not to have a mobile optimised design, your certificate design will be scaled down to fit on a mobile screen: