CSS variables

June 14th, 2012. Tagged: CSS

Weeee, CSS variables just landed in WebKit, this is pretty exciting!

Unfortunately I couldn't see them in action in WebKit nightly (must be something I'm missing), but they're here and here to stay. I know there are "purists" that say that stuff like variables has no place in the language and we don't really understand CSS, it's different, etc, etc. But once W3C has a modest proposal and one major engine is implementing variables, then this is where we're headed. And I personally applaud this direction.

Syntax

So the basic idea, according to W3C is this. There are two steps: you declare a variable (together with a value assignment) and then you use it.

This is a declaration of the variable my-color. It's a global variable (defined under :root).

:root {
  var-my-color: #fad;
}

Then you use it like:

.thing {
  color: var(my-color);
}

And the .thing gets the color #fad.

In WebKit

Webkit currently uses a -webkit vendor prefix which makes the whole thing more verbose:

:root {
  -webkit-var-my-color: #fad;
}
 
.thing {
  color: -webkit-var(my-color);
}

There are many examples for your browsing pleasure in the form of test files in WebKit's repo

Future

It's here. And it's only getting better. There's a dev draft of the CSS variables proposal which talks about using $ instead of var() to refer to a variable, which is so much nicer. Spoken like a true php'ied, eh? :)

:root {
  var-my-color: #fad;
}
 
.thing {
  color: $my-color;
}

Exciting times!

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