[neals]

I wasn't paying attention the last time we had some awesome additions to CSS. How does something like this get adapted?

Do developers actually only use this on FF29+ until all browser adapt? Is this one of those things where we will see workarounds for older browser for decades to come?

Or is this more something that CSS frameworks like LESS pick up and the actual thing is abstracted away for a couple of years still?

This does seem like a very useful feature.

[thefreeman]

The good news is that at least now a large majority of users are on browsers with auto update. So once the spec is finalized and browsers start to enable it by default you should get a pretty large % of users who will support it.

You will likely have to have a separate stylesheet for older versions of IE (and possibly other browsers) but honestly you likely have that anyway. And it's a lot easier to update a few values in that then throughout your entire site.

We'll see how it plays out but I certainly wouldn't expect to use them in production for quite a while yet. I'm sure that is why they hid it behind an about:config option for now.

[TazeTSchnitzel]

LESS and co. can't implement this, because CSS variables are cascading.

[reimersjan]

According to caniuse, the global support for variables is 0.01% right now. http://caniuse.com/#search=variables

I think it will take some time until there is enough browser support to use variables on a productive site. but maybe browsers will implement this faster... there's hope

[gotofritz]

No, people will carry on using SASS until support for this feature is well and truly widespread.