I loaded a file that I knew didn't exist to Mozilla and edited the error message to make some real content for the page. I will see if the page actually gets saved.
As Proof I will actually leave the server info that appears as the end of the message. Next I will try to add some style info to the HTML and see if I can bootstrap into an edited webpage from just the browser. I just noticed that the display of what I am typing, which is rendered in the browser did not check to see if tags were properly balanced.