Beautiful and simple notepad PHP web app

I built it to be able to access and edit my notes on both my cellphone and computer. It is my GTD system and also my journal. I used Wunderlist and many others before, but all of them had problems, mainly randomly loosing notes, unpredictable sync or heavy to open.

Very fast
Dark background, console-like appearance
Responsive
100% write area, no menu, except for the small notification on the right bottom corner for when offline of if the content wasn't saved yet
You can create new files by directly editing the URL, ex.: you access domain.com/index.php?file=tasks and the tasks file will be created, everything you write will be there the next time you access the same address
Similarly, to delete files just access domain.com/delete.php?file=tasks
View created files at domain.com/list.php
Saves the content automatically every 3 seconds, if modifications have been made
Saves a backup for every modification made to the note at domain.com/bkp/. If you have Apache it can list these files for you like a file manager
No authentication

Just four files with less than 200 lines of uncompressed PHP and Javascript code, including, HTML, styles and line jumps
No database, just regular text files
Deployment: just drop the files on a web server folder

There's code for notifying the user of a newer version of the current document on the server, but it is disabled because of some issues, you can check out more details at the bottom of the index.php file