> By design a user agent is well within its rights to completely ignore any stylesheets attached to a page, and the idea was always that this should be completely OK, partly because you have no idea what the UA's capabilities are, up to and including whether or not it's doing any kind of visual rendering at all.
I think that is just an outdated idea that does not apply to highly interactive, long-lived web applications. The user agent is well within its rights to ignore anything it wants, of course, but the user agent is not owed anything by the server. With CSS, or JavaScript, the app may just not work.
> With CSS, or JavaScript, the app may just not work.
When it comes to CSS, generally most apps will continue to work even if the CSS is simply ignored.
Because that was one big point of CSS. Separation of presentation from content and function.
It's funny. That kind of separation of concerns is something developers talk about valuing, but the SPA/webapp craze erodes the user-facing aspect of it, even while developers are very proud to demonstrate they're thinking hard about which specific kind of separated-concern architecture they're working with well away from the boundary where an outside user or UA would care.
I think that is just an outdated idea that does not apply to highly interactive, long-lived web applications. The user agent is well within its rights to ignore anything it wants, of course, but the user agent is not owed anything by the server. With CSS, or JavaScript, the app may just not work.