Think about user changing the default UI font. OS X and Windows both make it difficult to impossible, and for this exact reason. On Linux, though, it's common and expected (which is probably why all UI frameworks that target it do have some decent dynamic layout support).

But aside from font family, there's also the issue of font size. That one can be cranked up on high-DPI displays, or for accessibility purposes.

> I find html/css just painful to work with

Don't get me wrong, I'm certainly not praising HTML5 and CSS here. They're vastly overcomplicated for what they do, for app development. And layouts are a long solved problem in desktop UI frameworks - Qt, Tk, Swing, WPF are just a few examples. WPF in particular is a good example of an XML-based markup language specifically for UI, and it's light years ahead of HTML5 in terms of how easy it is to achieve common things, and how flexible things are overall.

If even half the time and energy invested into building "web apps" (including all the Electron-based stuff) went into an existing UI framework - let's say Qt and QML - we'd all be much better off; developers with far more convenient tools, and users with apps that look and feel native, work fast, and with smaller download sizes (because you aren't effectively shipping the whole damn browser with them).