How to change popup size only on mobile phones

Hello @ricardomat ??

To manually control the design of a single campaign across different screen sizes you’ll want to use Custom CSS and media queries. See our guide here to get started adding CSS to your campaign: https://optinmonster.com/docs/how-to-use-optinmonsters-custom-css-tool/

Alternatively, with a Pro or Growth subscription you can create separate campaigns for different devices for fine-tuned control through the builder: https://optinmonster.com/docs/how-to-create-a-mobile-optin/