Webkit vendor prefixes produce Typescript errors

[kevinwcyu]

Describe the bug
Using WebkitBoxOrient and WebkitLineClamp properties in the sx prop produces Typescript errors.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'https://codesandbox.io/s/repro-theme-ui-webkit-properties-3crbb?file=/src/App.tsx
2. See error errors produced in the sx prop of the Box component in lines 8–11.

(property) WebkitBoxOrient: string
Type 'string' is not assignable to type 'ThemeUIStyleObject'.ts(2322)

(property) WebkitLineClamp?: number | ThemeUICSSProperties | CSSPseudoSelectorProps | CSSSelectorObject | VariantProperty | ... 9 more ... | undefined
...
Type 'number' is not assignable to type 'ThemeUIStyleObject'.ts(2322)

Expected behavior
The Webkit vendor prefixes should not produce Typescript errors. See this comment for reference #234 (comment).

Additional context
The line clamping still works as expected, it's only the Typescript error that is not expected. See the output of the provided codesandbox. Removing the WebkitBoxOrient and WebkitLineClamp gets rid of the Typescript errors.

The provided codesandbox uses 0.4.0-rc.1 of theme-ui but it is also present in 0.3.1.

[hasparus]

Hey @kevinwcyu! Thanks for the issue.
We've fixed it in @next 0.4.0-rc.5 version.

[kevinwcyu]

Hi @hasparus, thanks! Just tried it out and it works.

[hasparus]

Glad to hear that!