Identify columns with meaningful data: Add a custom column to the summary table to compare the `Count` and `Null Count` values. This step helps pinpoint columns that contain actual data.

You must unblock the zip file before extracting. Right click on the zip file in Windows Explorer and select Properties. If you see an Unblock button or checkbox then click it. Extract the zip file and ...

For example: if you enclose a whole media query in a comment intending to disable its rules, you'll probably find that those rules will end up enabled in non-media-query-supporting browsers.