Ignoring Webkit-specific CSS selector in Firefox - css

Question

I'm working on a jQuery theme which includes styling for as many form elements as possible.
Initially it was developed for Webkit (Chrome). Now I want to make it work with Firefox as well.
Problem is; Firefox has problems with some Webkit-specific syntax.
For example:
input[type="range"]::-webkit-slider-thumb,
input[type=radio],
input[type=checkbox] {
-webkit-appearance: none !important;
-moz-appearance: none;
width: 1.2em;
height: 1.2em;
border: 1px solid black;
background: #666666 url(images/ui-bg_highlight-soft_50_666666_1x100.png) 50% 50% repeat-x;
}
The problem is the input[type="range"]::-webkit-slider-thumb, bit. Remove it and Firefox works fine. It also does this for other syntax like ::-webkit-file-upload-button, ::selection and all other things using the ::-webkit-... labels. It recognizes it's own ::-moz-... labels, like ::-moz-selection just fine though.
Webkit seems to just ignore the ::-moz- labels.
Is there any convenient way to make Firefox ignore the ::-webkit-... labels or otherwise deal with this problem without having to maintain multiple copies of every CSS block?
Using freshly updated versions of Chrome and Firefox.

Answer 1

Unfortunately, it's not possible without duplicating the declaration blocks, as the CSS spec stipulates that browsers must behave this way when encountering unrecognized selectors in CSS rules:
The selector consists of everything up to (but not including) the first left curly brace ({). A selector always goes together with a {}-block. When a user agent can't parse the selector (i.e., it is not valid CSS3), it must ignore the {}-block as well.
In this case, it's one vendor's browser being unable to recognize another vendor's prefixes, so it has to ignore the rule.

Answer 2

I had to read a little bit to answer this question, here are some good resources,
Gecko Style Engine Further Reading on the Engine Implementation, Still i did not see any pointers as why it would drop it, but i can give you my best guess, I think the engine is dropping the whole selector, suppose that mozilla implements -moz-slider-thumb pseudo selector and try to use it with -webkit- and it will be dropped as well.
I have seen this behavior before in all browsers, and i think its being used as a hack to target some browsers sometimes.
This will work
input[type=radio],
input[type=checkbox] {
-webkit-appearance: none !important;
-moz-appearance: none;
width: 1.2em;
height: 1.2em;
border: 1px solid black;
}
This wont
input[type="range"]::-webkit-slider-thumb,
input[type=radio],
input[type=checkbox] {
-webkit-appearance: none !important;
-moz-appearance: none;
width: 1.2em;
height: 1.2em;
border: 1px solid black;
}
or this
input[type="range"]::-moz-slider-thumb,
input[type=radio],
input[type=checkbox] {
-webkit-appearance: none !important;
-moz-appearance: none;
width: 1.2em;
height: 1.2em;
border: 1px solid black;
}
I think you will have to rewrite the properties-values on two or more different selectors, this will only affect the size of the stylesheet as the engines will keep dropping the selectors they dont own.
I really hope this helped a little bit at least.
EDIT:
As noted by user #BoltClock in the comments my guess was correct here is a link to the spec w3.org/TR/css3-syntax/#rule-sets

Answer 3

FYI, I ended up going for a different solution.
Since my end product is a stylesheet, I decided to use a CSS compiler to generate the .CSS file based on a source file. So far it's working fine.
I've used LessPHP because the .less format is reasonably popular and I'm familiar with PHP, but any of the other ones will do.
Note that I'm using LessPHP only for compiling a static .CSS file, so it won't be a requirement for end-users of this project unless they want to change the .less source files themselves.