What are the legal requirements for using popups in different regions (e.g., GDPR)?

To make your Shopify popups mobile-friendly and responsive, focus on design and usability. Keep popups small, unobtrusive, and easy to close. Use responsive templates that automatically adjust to screen size, and avoid large images that slow loading. Test popups on different devices to ensure they look good everywhere. Delay triggers so they don’t annoy visitors right away, and prioritize fast load times. Apps like OptinMonster can simplify the process with built-in mobile optimization.