Not a mac user here - why can't you use the same method to set the corner radius to 0.1 or something and effectively turn of the roundness, but without root?
>The reason why you need to disable SIP, is that to edit the dynamic libraries that system apps like Safari (which has crazy bad corners) use, you need to edit system libraries that exist the root.
>The reason why you need to disable SIP, is that to edit the dynamic libraries that system apps like Safari (which has crazy bad corners) use, you need to edit system libraries that exist the root.