I think they used separate style sheets. Going way back in time, to the early days of smartphones and back when non-smartphones had mobile web browsers, most websites would serve either a separate style sheet that gave a simplified layout for tiny screens or even an entirely different, simplified page. Early adopters to mobile browsing tended to hang on to that separation much longer than newer sites that took advantage of CSS that could adapt to the screen size.
I think they used separate style sheets. Going way back in time, to the early days of smartphones and back when non-smartphones had mobile web browsers, most websites would serve either a separate style sheet that gave a simplified layout for tiny screens or even an entirely different, simplified page. Early adopters to mobile browsing tended to hang on to that separation much longer than newer sites that took advantage of CSS that could adapt to the screen size.
Yeah, this is a remnant of Wikipedia supporting mobile devices really early.
Honestly I generally prefer the desktop sites and just zooming in than mobile sites that tend to badly fit everything on the screen.