You are confusing two things HTML is not a computer program.... the computer program that ""establishes the format of text and graphics on the computer screen when a website is viewed""... is actually what FireFox does and what IE, Safari and other browsers do... those programs are what they are talking about. The HTML defines the layout.. the program that renders it is the computer program.
Are you trying to say web browsers cannot be copyrighted? Please think carefully about your answer as a multi-billion dollar industry depends on the dillusion that you can actually copyright a browser (and any code in fact).
Look at the top of any source code file, the first line is normally a copyright statement. You don't need to register copyright for it to be yours.