Attributes: Meh, pointless.

Constants: I run my CSS through a templating system if I want to do that kind of thing. The templating is already an essential part of my site framework, as it has been since I was using PHP3.

Concatenation: Meh, pointless.

Calculations: Done at time of templating, see constants.

–

Of all of these libraries, this is the least pointless and annoying.

Unfortunately the bar in this field is set pretty low to adequately reflect the pointlessness of it all, and so CleverCSS manages to win that title despite being still really quite pointless and annoying. All IMHO, of course :)

@WillPeavy – Calling them dynamic stylesheets is a little incorrect. Nothing here needs to be determined at runtime. It could easy be made static using a build tool or something.

For everyone else saying this kind of thing isn’t necessary – its only made necessary by the size or type of your project. I would say that the most important things needed are variables and calculations. Everything else here doesn’t really add functionality as much as offer a different syntax. I think that part is mostly personal taste.

Personally, I just use Velocity templates. Its really simple but effective. I can still use syntax highlighting and autocomplete from netbeans, but I can also easily do calculations and variables. It also lets me easily break apart my css into different files and concatenate using includes. However, the biggest win for me, is the ability to call into Java code. I built an image generator library that uses Java2d to create rounded corners, gradients, and other effects and put those and other icons into image sprites, and spit out the necessary css to make it work.

Something like:

.table-row .left-top-corner {
$image.corner("corner(top left) bgColor(#EFF2F3) color(#FFFFFF) radius(8)")
}

generates the image for a corner, puts it in an image sprite, and then templates in the css for size and background image url and offset.

I would, however, love to see a solution where browsers could understand other languages as “styling” languages. For example, consider the power of a JavaScript/jQuery based styling format, let’s call it JSS (JavaScript Style Sheets). This would cover all (or at least most of) the shortcomings of CSS, with support for variables, math, etc. Optimally, this could lead to smaller static (cachable) files for example. JSS could be an alternative, or complimentary technology to CSS, that is given the same status as CSS in the browser rendering process.

You need variables (or at least constants) so that you can define some commonly used colors, urls, etc. at the top of your document then only have to change them in place.

You need math you so can do stuff like { width: 100% – (<some expression for getting my left border with) + ) }

You need scope so that if you want to target several elements within #someDiv, you don’t have to type $someDiv at the beginning of every line. Maybe like:
#someDiv [
ul {}
span {}
a {}
]

The rest should be obvious.

Don’t know how I feel about that. Most of the things that people seem to say they want CSS able to do you can already with Javascript. Ah yes, people turn off Javascript, true. But if CSS becomes a scripting language then people might be tempted to start turning CSS off.

HTML5 is leaning towards being a programming language and now CSS? I guess things just are confusing and bloated enough for some people.

What am I missing?

in all cases, i’ve found a more elegant solution using plain old CSS, usually using adjacent selectors and maybe an extra class here or there.

I’d actually like to see (and would be interested in helping to produce) an HTML 5 platform that let’s you target HTML 5, with maybe some extras like this kind of CSS abstraction and possibly even HaXe support for scripting – that will compile down to the HTML hack soup that we all have to deal with now by hand. Most HTML 5 features can be handled by Javascript and some CSS hacks – maybe a plugin here and there (audio and video), so I don’t see why not. Dean Edwards even made his IE7 and IE8 scripts, which to me are more than enough of a proof of concept.

I would love to not have to deal with hack soup any more, and just target HTML5. That would be awesome.

If you’re going to mix to syntaxes I’d want to be able to differentiate when one stops and another takes over. But the above mentioned solution would make my head hurt going back and forth between using these and writing plain vanilla CSS.

You’ll be my hero when i see the PHP port!

Yeah… If only there was some sort of standard that defined rules for applying styles to a web page…

*cough* http://www.w3.org/TR/CSS2/ *cough*