both declare the $tab-active-bg-color variable to "grey-200" instead of "$grey-200." The results in the string literal "grey-200" being output in the CSS for the value of the background property in some places, which is invalid.
navigations/styles/accordion/_bootstrap-definition.scss and navigations/styles/accordion/_bootstrap-dark-definition.scss
both declare $acrdn-header-hover-bg and $acrdn-header-active-bg as ''. This results in an empty string being output in the CSS for the value of the background property in some places, which is invalid. Maybe the default should be transparent, which is valid CSS, and would result in no visible background?
Those are the only instances I saw, but I would recommend putting all of the generated CSS files through a CSS validator, to see if anything else shows up.