[joe5150]

I think it's helpful to keep in mind that any design will be to some extent "OS-specific" for a lot of different reasons, available fonts being only one factor.

I also think OS-specific design is perfectly appropriate for a lot of use cases. I use "font-family: system-ui, sans-serif" on my resume page, for example, because I know that the default system fonts look fine (by design) on any screen and a fast, lightweight page is more important to me than a specific font presentation. If you're creating a user interface with really tight tolerances on element size or appearance, different strategies might be more appropriate.

[hLineVsLineH]

> I use "font-family: system-ui, sans-serif" on my resume page [...] If you're creating a user interface with really tight tolerances on element size or appearance, different strategies might be more appropriate.

Shouldn't it be the opposite? It literally has "UI" in the name, and according to the the spec, "The purpose of system-ui is to allow web content to integrate with the look and feel of the native OS."

The text on a resume is not UI, and it has no need to fit the look and feel of the native OS. In this case you should just use `serif` or `sans-serif`. If you're creating a user interface, then it would be appropriate to use `system-ui`.

[joe5150]

> The text on a resume is not UI, and it has no need to fit the look and feel of the native OS

My resume has no need to look any particular way at all; this is just my preference. You should design your webpages however you like!

[jfk13]

You may happen to like how system-ui looks on your system (macOS? Windows?); but do you have any idea what it looks like for the person reading your resume, perhaps on Linux with a custom theme, or on an Android device where the vendor chose to ship some brand-specific UI font? Or on a 5-yr old version of the OS, or on the version that'll be current 5 years in the future?

IMO system-ui is hardly ever a wise choice for content.

[zinekeller]

> Android device where the vendor chose to ship some brand-specific UI font

Chrome (and Android Webkit) hardcodes Roboto as the system-ui font (in such a way that both Samsung and Xiaomi devices (which both have font options) cannot touch), and Firefox brings its own font rendering which also hardcodes Roboto.

If the system-ui font of Linux is set to a silly one (according to your opinion), then the user-in-question would realise that they are the one who picked that font that you called silly, in other words they don't care about your opinion at all.

[djur]

If it is legible I don't care. If I can select a style a little bit more specific than "serif" or "sans-serif", that's great, as long as it degrades to something legible. I've yet to see a situation where free-flowing text or headings became illegible because the font changed. UI elements, sure.

[philistine]

It simply puts a bit more trust on the user than normal. And if your OS has a ridiculous system-UI font that can't handle paragraphs well, you have bigger problems than some website.

[madeofpalk]

Emphasis on "really tight tolerances". If you build a UI relying on the specific metric of a font (as misguided as that may be), system-ui will be a poor fit because it will have different metrics on different operating systems.