If the server side has changed then I can simply refresh the page if I want the newest page. I'd like the page to be exactly what it was when I closed the browser. I've left computers running for days just to save the state of a single browser tab. I suppose a better way of doing it is to only use browsers inside a VM and them just save the state of the VM.

About websites: I don't want to have to rely on website makers, because they invariably won't do it and it won't work.