Caniuse: Add CSS Color Level 4 new rgb and rgba syntax

[daytonlowell]

Chrome, Firefox, & now Safari Technology Preview support it.

The differences are:

There is a new comma-free syntax, where the optional alpha is separated by a slash:
rgb(128 34 56)
rgb(128 34 56 / 50%)

Floating point values are allowed, and rounded:
rgb(128.5 34.2 56.5) becomes rgb(129 34 57)

rgba() is a pure alias for rgb(), so these are equivalent:
rgb(128 34 56 / 50%)
rgba(128 34 56 / 50%)

webkit bug: https://bugs.webkit.org/show_bug.cgi?id=192321

[felixdivo]

As well as lab()/lch()/... from this Editor’s Draft maybe?

[Ugoku]

Browser issues for lab/lch support:

• Chromium: https://bugs.chromium.org/p/chromium/issues/detail?id=1026287
• Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1352757
• Safari: https://bugs.webkit.org/show_bug.cgi?id=205675

[Schweinepriester]

+1

Syntax with 4th parameter also spec'd for HSL: hsl(0 0% 0% / 20%); 🎉

• https://www.w3.org/TR/css-color-4/#the-hsl-notation
• https://twitter.com/argyleink/status/1218305696862588928

[mathiasbynens]

Duplicate of #2679