Calling a CSS class inside another class?

Question

Is it possible to have one CSS class reference another? Instead of rewriting all the css code again?

For example, I have this:

.btn{
    /* Whatever btn related styles I have */
}

.btn:hover{
    box-shadow:0 0 4px black;
}

.btn:active{
    /* This is where I want to reference the '.red' class */
}

.red{
    /* There is a LOT of CSS code here for cross browser gradients */
}

The thing is, I'm already using the .red class as is in certain places, and I'd also like to apply the same gradient style to the 'active' state of all elements with the .btn class...

If you can help solve (it need not be the way I've requested it) this, I'd greatly appreciate it...

Answer 1

You can't actually do a reference (one of CSS's major failings), but you can do this:

.btn:active, .red {
    /* Block A: Most (or all) of what used to just be in .red below */
}

.btn:active {
    /* Block B: Stuff *just* for .btn:active, if any */
}

.red {
    /* Block C: Stuff *just* for .red, if any */
}

The comma means that the definitions in the body of Block A apply separately to each of those selectors, and so they apply to any ".btn" elements that are ":active", and separately apply to any ".red" elements.

Block B and Block C are optional. They're for any definitions you only want to apply to the given selector. You usually list these after Block A because rules of equal specificity are applied top-to-bottom, so you can override anything from Block A that you want to in Block B or Block C, and those blocks will "win".