An unexpected revival of Firefox OS
The dream of an HTML-based operating system is nothing new, and in fact, something we have seen since the early 2000s. With the Internet exploding in popularity and complexity, it has always been tempting to think of browsers as convenient graphical renderers, and CSS as the ultimate markup language for designing complex UI elements.
However, reality has often clashed with this view. Many projects proposing an HTML5 or JavaScript desktop UI have historically shown bottlenecks even on high-spec machines, and although a subset of CSS is finally being used in the majority of "traditional" toolkits such as Qt, Cocoa, and GTK, the adoption of JavaScript logic to control desktop frontends is still lagging behind. Aside from Google's Chrome OS, Electron, and many other projects, the whole GNOME Shell frontend runs on top of a JavaScript interpreter... and sometimes it shows.