[lambda]

Unfortunately, font-variation-settings isn't supported by Firefox, Safari, IE, or older versions of Edge, so these settings only work for ~70% of users according to Can I Use.

It was a bit frustrating viewing this site on Firefox and not having any indication of why the settings weren't changing anything.

Of course, maybe that's because there hasn't been enough demand for it, and now that there is a font that's widely available which can use this, Firefox might finish enabling it (looks like there is a flag for it, but it's not enabled by default).

[heycam]

Support for font-variation-settings has been on by default since Firefox 62, which was released almost two years ago. Are you using a Firefox older than that?

[lambda]

Ah, sorry, I was looking at the wrong item on "Can I Use...", @font-face: font-variation-settings, rather than the "Variable Fonts" item which covers font-variation-settings outside of @font-face rules.

https://caniuse.com/#search=font-variation-settings

And I am running an ancient version of macOS, 10.12, which explains my issue, as it's only supported on macOS 10.13+ in Firefox.

I have a new (non-macOS) laptop in transit, but my current daily driver is an old Mac.

Sorry for the alarm!

[nedbat]

The sliders on the site work for me in Firefox, v78.0.2.

[augstein]

Also in Safari iOS 13.6

[jsjohnst]

> Unfortunately, font-variation-settings isn't supported by Firefox, Safari, IE, or older versions of Edge

Seems to work fine for me on Safari