[subpixel]

I use Safari web archives for a similar task.

But I wonder...isn't it safe to assume that, eventually, browser rendering engines* will change to the degree that something I saved 4+ years ago is essentially unreadable?

And doesn't that same potential problem apply to a hosted service as well?

*I'm using that vague term to describe everything I don't understand about how browsers render pages, markup, and javascript, which is a lot.

[dangero]

I agree. I think the safest bet would be to keep a static image as well. Without a static image would will always question if the rendering engine has even slightly changed the look.

[hexley]

Maybe save as a PDF if it's the content you're most interested in.

[subpixel]

I save screenshots for that, but when I save an archive it's usually b/c I'm interested in referencing non-static elements. Like animation, transition, responsive behavior, etc.