CssVars should not be camel-cased

[texels]

Expected behavior:
I tried to put a css variable into the jss object on the jss playground:
"--helloWorld" : "red",
I expected this to remain untouched. Instead it was converted to:
--hello-world: red;

Describe the bug:
css variables should not be camel-cased

Codesandbox link:
Enter this into the jss playground:

export default {
button: {
"--helloWorld" : "red",
border: '1px solid var( --helloWorld )',
}
};

Versions (please complete the following information):

• jss: The one on https://cssinjs.org/repl/
• Browser: chrome
  -OS: macOS

Feel free to add any additional versions which you may think are relevant to the bug.

[kof]

Oh I get it, you wrote camel cased custom prop, but because of the conversion you have to use a hyphenised version of it in (var()), so it becomes inconsistent from the consuming perspective, unless you write the first one also hyphenised.

yeah, I think we should not convert custom props

[HenriBeck]

Fixed in #1017. Will be in the next alpha