Title: Invalid CSS
Last modified: June 11, 2026

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# Invalid CSS

 *  [bagnall](https://wordpress.org/support/users/bagnall/)
 * (@bagnall)
 * [3 days, 8 hours ago](https://wordpress.org/support/topic/invalid-css-4/)
 * When running w3c validator on our WordPress site using Sydney theme, we get a
   lot of errors relating to the CSS (in our case at line 68).
 * ![](https://wordpress.org/da7b18f1-fefa-4dad-ac8d-c22fe4833ba2)
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Finvalid-css-4%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

Viewing 2 replies - 1 through 2 (of 2 total)

 *  [Rajab Said](https://wordpress.org/support/users/snrjosh/)
 * (@snrjosh)
 * [1 day, 20 hours ago](https://wordpress.org/support/topic/invalid-css-4/#post-18937011)
 * Hi [@bagnall](https://wordpress.org/support/users/bagnall/),
 * Thanks for contacting us!
 * W3C validator errors on CSS files can be concerning, but let’s walk through this
   together to identify what’s happening. Here are a few clarifications:
    - The Sydney theme uses vendor prefixes like `-webkit-`, `-ms-`, and `-moz-`
      in its CSS. These are entirely valid and necessary for cross-browser compatibility.
      Most modern CSS employs them, and they shouldn’t affect how your site displays
      or functions.
 * To get the full context of what you’re seeing:
    1. **Can you share the exact error message** from the W3C validator? Just copy 
       and paste the full error (including what property/value it’s complaining about).
       The line number can vary depending on how CSS is loaded, so the actual error
       text is more helpful.
    2. Please let me know if the issue appears when you validate your homepage versus
       inside pages.
 * Typically, most W3C “errors” in WordPress themes are related to standard vendor
   prefixes. However, if they affect functionality or appearance, that’s something
   we’d definitely investigate further.
 * Once I get these details, I can provide a more targeted advice!
 * Thanks.
 *  Thread Starter [bagnall](https://wordpress.org/support/users/bagnall/)
 * (@bagnall)
 * [1 day, 12 hours ago](https://wordpress.org/support/topic/invalid-css-4/#post-18937108)
 * Hi Rajab, Thank you for getting back to me. I’m on leave for a week but will 
   give more detail when I’m back at work, but IIRC there were rules such as “color:;”
   with no color value. I tried to attach a screenshot with my original post but
   was unable to. When I’m back at work, perhaps I could email directly? In the 
   meantime, you can probably see the errors yourself if you run our front page 
   [https://podcast.langcen.cam.ac.uk/](https://podcast.langcen.cam.ac.uk/) through
   w3c validation filtering on errors.

Viewing 2 replies - 1 through 2 (of 2 total)

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 * ![](https://i0.wp.com/themes.svn.wordpress.org/sydney/2.68/screenshot.png)
 * Sydney
 * [Support Threads](https://wordpress.org/support/theme/sydney/)
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 * 2 replies
 * 2 participants
 * Last reply from: [bagnall](https://wordpress.org/support/users/bagnall/)
 * Last activity: [1 day, 12 hours ago](https://wordpress.org/support/topic/invalid-css-4/#post-18937108)
 * Status: not resolved