Add RGB css var generation on client side

[PatelUtkarsh]

Summary

Fixes #324

Checklist

• My pull request is addressing an open issue (please create one otherwise).
• My code is tested and passes existing tests.
• My code follows the Contributing Guidelines (updates are often made to the guidelines, check it out periodically).

[coveralls]

Pull Request Test Coverage Report for Build 2910980647

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.8%) to 72.189%

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Totals
Change from base Build 2910378663:	0.8%
Covered Lines:	4742
Relevant Lines:	6438

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💛 - Coveralls