I had to read through this twice, but I think I get it now (I’m not the sharpest knife in the drawer). Very useful if you’re doing theming in CSS.
On Ev’s blog, Marcin goes into great detail on theming an interface using CSS custom properties, SVG, HSL, and a smattering of CSS filters.
I was kind of amazed that all of this could happen via CSS and CSS alone: the colours, the transitions, the vectors, and even the images.
Oh, how I wish I could’ve been at Web Directions Code in Melbourne to see this amazing presentation by Charlotte. I can’t quite get over how many amazing knowledge bombs she managed to drop in just 20 minutes!
Mike examines the real power of CSS custom properties compared to Sass variables—they can change at runtime.
I’m convinced that in almost all cases, responsive design logic should now be contained in variables. There is a strong argument too, that when changing any value, whether in a media query or an element scope, it belongs in a variable. If it changes, it is by definition a variable and this logic should be separated from design.