Variable is a BIG change in CSS. If a browser doesn't support variable, then new stylesheets are already broken in that browser. It makes little difference to m

Variable is a BIG change in CSS. If a browser doesn't support variable, then new stylesheets are already broken in that browser. It makes little difference to make the syntax compatible. Once an easy-to-use syntax is published, toolchains that parse CSS will update as fast as they can! But "--"? Everybody will stick to the old standard and never want to upgrade.