I suspect it will go beyond CSS.<p>There are a certain kind of app on Android that makes the device FS available via a web browser.<p>Thing is that these apps invariably makes use of a Chrome-ism when dealing with drag and drop.<p>In Firefox you can only drag a single file at a time. drag over multiple, or a folder, and there won&#x27;t be much of a result.<p>In Chrome however it will transfer over just fine.<p>This has been sitting in the Mozilla bugtracker for some time, because the Chrome behavior goes beyond the HTML spec for file uploads.