Testing features of your app that does not use a native mobile language can be tricky if you don’t have a physical device. I found that using Chrome, Safari, and Firefox dev tools can each show a different view of a feature when testing on an actual mobile or tablet device. Most common bugs are related to CSS.
My team found this Chrome extension tool to help test and debug our app on tablets. Mobile simulator — responsive testing tool
Once installed, we can use the given instructions on how to use this extension
Hopefully, you can find this helpful to test your app in different screen sizes.
