Ask HN: How to get your designer to design for mobile and react-native

There is a constant issue that we are having where the designer is going to come up with a screen but while translating that into code for mobile in React-Native we end up having discrepancies on different screen sizes.

Also our designer is not familiar with DPI so when it comes to font sizes etc we are having issues finding a font size that will work well with different screen sizes.

My question to you is: Are there any tools for the job? We've tried some of them including Sketch and exporting to react-native but it seems a bit premature.

Are there any courses or books that we can recommend to our designer in order to make sure that his design can be translated and scaled into react-native?

Thanks for reading.