A client-side include tag: <include src="nav.html" /> It would work similar to a server-side include (e.g. <!--#include virtual ="nav.html" -->) but on the cli

A client-side include tag: <include src="nav.html" /> It would work similar to a server-side include (e.g. <!--#include virtual ="nav.html" -->) but on the client, so that it can be downloaded once and cached, then used across a site. You can get something similar with web components, or iframe/embed/object, but it really should be part of HTML.