backbround-color typo in tui-image-editor/src/css/range.styl

[ognjenkuljic]

HI,
Just to mention u created excellent package ;)

But there is an issue whet I try to build my project with your package on the latest version/tag -> 3.15.3
As I can tell this issue is fixed in -> 9ee993e
Can u plz create new version and include this fix?

Thanks