Updates Badge styles to use CSS variables

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Hoist P/R Checklist

Pull request authors: Review and check off the below. Items that do not apply can also be checked off to indicate they have been considered. If unclear if a step is relevant, please leave unchecked and note in comments.

• [x] Caught up with develop branch as of last change.
• [x] Added CHANGELOG entry, or determined not required.
• [x] Reviewed for breaking changes, added breaking-change label + CHANGELOG if so.
• [x] Updated doc comments / prop-types, or determined not required.
• [x] Reviewed and tested on Mobile, or determined not required.
• [x] Created Toolbox branch / PR, or determined not required.