Idea: show device offline in the main http page

[openshwprojects]

currently, when device is offline, it's not possible to tell that by looking at the main www page, which may have been open during last device session when it was still online.
I have an idea how to fix it.
We could just have a HTTP page script that changes background color (or something else, adds just a message? a status?) when device does not respond to HTTP page refresh calls for given amount of time.
That way it would be very easy to tell when device goes offline and online.
I may implement it in the following days, but I am still considering how to approach the idea.
Thoughts?