It's for having the correct dimensions:    <img width="227" alt="Capture d\u2019e\u0301cran 2020-09-12 a\u0300 13 09 35" src="https://user-images.githubusercontent.com/3165635/92994269-3adfc900-f4f9-11ea-88a9-5542ab0f9cf8.png">  