So just to your last point, no one can tell the difference between "you, the client, can no longer reach this particular server" and "this server no longer is u

So just to your last point, no one can tell the difference between "you, the client, can no longer reach this particular server" and "this server no longer is up". You might be able to tell that it's the user's connection, rather than a netsplit somewhere, with some reasonable degree of confidence (ping the ISP, ping google, etc), but that's a lot of work, still just a percentage chance of being correct, for no real benefit. To the rest...that's the point, it's just...CSS and JS. You can change it. You can show it or not, based on what the user is doing, or what view they have. Worst case, you can just hide it completely across everything, as you say, which is then no different from an SPA, except where functionality fails when you have no connectivity. Whether that leads to a better or worse user experience is dependent on the dev's handling of those failures.