It's easy to use an icon with less contrast:
Both Firefox and Chrome use this kind of icon for sites without a favicon.
A sheet of paper is also commonly used as an icon for unidentified file types.

A globe is often used to symbolise the Internet and could be used by itself or with the document base:

One could use a chains or something which looks a bit like a webpage , but that would feel... weird?

A simple square would be fine, too.

Of course there could be better ideas, these are just some quick thoughts.
posted by [Old Forum guest] • 8 years and 4 months ago Link