Hi there!
The System Default fonts will be different for devices. Selecting this in the typography settings tells the browser to use the default fonts of the operating system or device.
If you use a Windows machine when checking on desktop, then fonts will be different when you view it on an iPhone for mobile.
Each operating system has its own default font stack:
- Windows: Segoe UI
- macOS/iOS: San Francisco
- Android: Roboto
- Linux: Varies (e.g., Ubuntu or DejaVu Sans)
If you want the fonts to look the same for desktop and mobile devices, choose any other font family that is not System Default.
I hope this helps, and let me know if I can assist you further.