CSS validation errors

[aspnetguy]

can someone explain what this error means...since when does opacity not exist????http://jigsaw.w3.org/css-validator/validat...;usermedium=all

[jlhaslip]

<span style="float:left;filter:alpha(opacity=25);-moz-opacity:.25;opacity:.25;"><img src="http://www.mandarindesign.com/images/v90.gif" width="50" height="50"></span>	#lightbox	{		display:none;		background: #000000;		opacity: .5;		filter: alpha(opacity=50);		position: absolute;		top: 0;		left: 0;	}

Here is a sample of some css opacity code which does work. Followed by your opacity code.Is it possible that the entire ID'd element does not accept the opacity attribute? Maybe post your (x)html code to see if you are trying to add opacity to an element which may not be acceptable to the opacity attribute? For example, you can add opacity to pictures, but perhaps not paragraphs??? Only thing I can think of...*EDIT*A check of the index of the w3c css 2 specs finds zero results for "opacity", "filter", or "alpha", so where are they hiding the information on Opacity?*EDIT 2 *Further research shows that the "opacity" property is not officially included in the CSS Specs until CSS3 under the guise of the SVG implementation, so the validation of the CSS must be using guidelines from prior to the SVG standards.Check the link below. That doesn't mean the Browsers do not implement the property, but the CSS Validator would be programmed to not allow it before the CSS3 standards??? I don't know any more than this. Maybe someone else has another take on it...http://www.w3.org/TR/css3-color/#profiles

[aspnetguy]

thanks for doing all that research. It does indeed work just doesn't validate. Oh well, not valid CSS for me

[pulpfiction]

There is some discussion related to this... as it suggests, you can use JS to apply the opacity and your CSS will be valid too.http://www.sitepoint.com/forums/showthread.php?t=454906

[Jonas]

I notice if you check/validate for css 3 spesification, then it's only the filter thing that's not valid:http://jigsaw.w3.org/css-validator/validat...=1&profile=css3Is filter: alpha(opacity=100); still necessary to use for IE?