WinSCP was not able to determine the application that was started to open the file. WinSCP cannot watch for changes in the file and thus it won't upload the changed file back.
One possible reason for the problem is that the file was opened in some already running application.
If you want to use the application to open files from winSCP, consider configuring it as an external editor. Note that the file will remain in temporary folder.
OK, but that does not say anything about not recognising CSS files. You would get the same message for any file. Also the text gives a solution, please follow that.
I also have another problem. When I try to drag folders from my server to my local files it says that the "drag feature" is not enabled, or something to that affect. This problem is only on one of the two pc's I have, however. Thank you!
What is your version of Windows?