This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
Even when set to CSS 3 mode the validator claims that 'background-color: rgba( 50, 50, 50, 25% );' is not valid. ("Too many values or values not recognized")
background-color: rgba(50, 50, 50, 25%) is not a valid value of rgba, http://www.w3.org/TR/2008/WD-css3-color-20080721/#rgba-color it can be rgba(number, number, number, number) or rgba(percentage, percentage, percentage, nuber).
See http://qa-dev.w3.org:8001/css-validator/ for css3 color validation.