One of the things in HTML5 that caught my eye a while back was the new 'scoped' attribute for style tags. The idea of it is that you can include a style element mid-document, mark it as scoped and its declarations will only apply to the style elements parent element and its child elements. The styles won't affect anything outside this. The biggest problem with bringing in this attribute is that it's not backwards compatible. If you include a style block mid-page, its declarations will be applied to ever element whose selector matches, inside or outside scope. It is anti-progressively enhancable. This means that designers and developers can't start using it until there's enough support. What we need is another of those JS tricks to make it usable.

My first attempt at solving this problem with JS involved generating a unique class, adding it to the parent element and then parsing the style blocks using JSCSSP so that I could rewrite them with the new class to add specificity. This approach only worked for the most basic declarations, unfortunately. The parser worked perfectly but there's a lot of detail in CSS specificity that mean this would be a much larger problem than I thought.

My second attempt involved:

1. Allowing the style blocks to affect everything on the page (at which point, the elements in-scope look right, those out-of-scope look wrong)
2. Using JS to read the current computed styles of each element in-scope and copy them to a temporary array
3. Emptying out the scoped style element (in-scope look wrong, out-of-scope looks right)
4. Copying the styles back from the temporary array onto each element

This worked great unless you had more than one scoped block – step 1 allowed scoped styles to affect each other.

The current attempt involves temporarily emptying all other scoped styles before taking the computed styles from a block. I'm now just thinking that this method might not work if you have multiple scoped blocks within the same context. Oh well, there's something to fix in the future.

This is where I'm at just now.

Yes, it's a mess, yes the JS is scrappy and yes, it doesn't currently work in IE but I'll get round to that next. It took long enough to get it working in Firefox as there's no simple way to convert a ComputedCSSStyleDeclaration to a string in Mozilla unlike Webkit's implementation of cssText or IE's currentStyle. I might even make it into one of those new-fangled jQuery plugins everyone's using these days.

You may have seen Google's 'Watch this space' advertising appearing all over the place. They have quite eye-catching diagonally striped backgrounds in various colours. A couple of days ago, I was wondering how easy it would be to recreate this in CSS without images. Unfortunately, the state of CSS 3 is such that some things work wonderfully, some just plain don't (scoped attribute, I'm looking at you). The following code relies on vendor extensions and so, unless you're willing to tend it and correct it after the spec is finalised, don't use this on a production server.

The most obvious thing to notice from the following code, though, is the competing syntax for the repeating linear gradient style. Mozilla have separated it into a distinct style (-moz-repeating-linear-gradient) while Webkit have built it as an option to their general gradient style (-webkit-gradient).

body {
	background-image: -moz-repeating-linear-gradient(
		-45deg,
		transparent,
		transparent       25%,
		rgba(0,0,0,0.15)  25%,
		rgba(0,0,0,0.15)  50%,
		transparent       50%,
		transparent       75%,
		rgba(0,0,0,0.15)  75%,
		rgba(0,0,0,0.15)
	);
	background-image: -webkit-gradient(
		linear,
		0% 0%,
		100% 100%,
		from(transparent),
		color-stop(0.25, transparent),
		color-stop(0.25, rgba(0,0,0,0.15)),
		color-stop(0.50, rgba(0,0,0,0.15)),
		color-stop(0.50, transparent),
		color-stop(0.75, transparent),
		color-stop(0.75, rgba(0,0,0,0.15)),
		to(rgba(0,0,0,0.15))
	);
}

To get a better idea of what this does, view source on this demo page. This includes a button to change the class on the body (using JS) which simply changes the background colour – the stripes are semi-transparent on top of that. Remember, due to the vendor prefixes, this only works in -moz or -webkit browsers.

It's supposed to look like this:

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