CSS Validation error

2 posts, 0 answers
  1. Arun
    Arun avatar
    15 posts
    Member since:
    Apr 2009

    Posted 28 Aug 2009 Link to this post

    Hi Team,
       I am facing css validation erros when the site is submitted to W3c Css Validation
    I am not sure of why i am getting these errors. Could you advice me on this. I have also attached the error report
    74 .rrButton:hover  Parse Error opacity=100)    
    75 .rrButton:hover  Property opacity doesn't exist in CSS level 2.1 but exists in [css3] : 1    
    76 .rrButton:hover  Property -moz-opacity doesn't exist : 1    
    77 .rrButton:hover  Property -ms-filter doesn't exist : "progid:DXImageTransform.Microsoft.Alpha(Opacity=100)"    
    115 .rrButton.rrButtonDisabled  Parse Error opacity=20)    
    116 .rrButton.rrButtonDisabled  Property opacity doesn't exist in CSS level 2.1 but exists in [css3] : 0.2    
    117 .rrButton.rrButtonDisabled  Property -moz-opacity doesn't exist : 0.2    
    118 .rrButton.rrButtonDisabled  Property -ms-filter doesn't exist : "progid:DXImageTransform.Microsoft.Alpha(Opacity=20)"    
    130 html  Parse Error html* .rrVerticalList li { float: left !important; }    
    86 .RadRotator_Default .rrButton.rrButtonDisabled  Parse Error opacity=20)    
    87 .RadRotator_Default .rrButton.rrButtonDisabled  Property opacity doesn't exist in CSS level 2.1 but exists in [css3] : 0.2    
    88 .RadRotator_Default .rrButton.rrButtonDisabled  Property -moz-opacity doesn't exist : 0.2    
    31 .RadPanelBar .rpSlide  Property zoom doesn't exist : 1    
    64 .RadPanelBar .rpLink  Property zoom doesn't exist : 1    
    126 .RadPanelBar .rpGroup  Property overflow-x doesn't exist in CSS level 2.1 but exists in [css3] : hidden    
    Thanks and regards,
  2. Martin
    Martin avatar
    585 posts

    Posted 28 Aug 2009 Link to this post

    Hello Arun,

    First of all, we do not claim valid CSS, only valid markup, however I will try to explain the causes for these errors.

    As you know, every browser has a set of its own CSS properties (called vendor-proprietary) which resemble the valid W3C properties (that are not yet implemented in the given browser for some reason). For example - the old versions of FireFox implemented the -moz-opacity property which does the the same as the CSS3 opacity property. On the other hand, in the early 90s, Internet Explorer 5 was the first browser to support element opacity. However, the Microsoft CSS opacity is achieved with the filter (that became -ms-filter in IE8) property, i.e - element { filter: alpha(opacity=50) }. The filter is an ActiveX CSS implementation from Microsoft that can be used for adding cool effect and transitions a la <canvas />. As Internet Explorer still does not support the valid opacity property, we are forced to use filter or -ms-filter. This is why you are getting these CSS errors, and unfortunately we cannot fix them until there are users with older FF (1x / 2x) versions and until IE does not support CSS opacity.

    You may read more about CSS filters at MSDN:


    Also, you may take a look at the following articles about the new -ms-properties:


    And finally - about the -moz-, -khtml-, -o- and other vendor-specific properties:


    Sincerely yours,
    Martin Ivanov
    the Telerik team

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