CSS validation of double semicolons

Some build tools will fail to process css with double semicolons such as this

..foo {
    margin-top: 20px;;
}

On several occasions over the years all local tests pass and we deploy to QA to find that the minified CSS is missing. We plug the CSS into the validator and it comes back all green, no warnings, no errors, perfect CSS, so we go looking for other issues and it takes much longer than it might to find that the CSS is in fact the issue.

Please consider adding warnings for double semicolons.

Thanks.
Dave


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