I suspect this is due to a bug in cssQuery, which Selenium currently uses to locate elements by CSS. Details of the issue and a patch can be found in the comments of the following issue: http://jira.openqa.org/browse/SEL-698
Hope that helps - I believe Selenium 2 will be using a different library for CSS locators - possibly JQuery's Sizzle (http://sizzlejs.com/), which should solve this problem.
Dave.
Answer from Dave Hunt on Stack OverflowVideos
Why Use CSS Selectors in Selenium?
How do CSS Selectors improve test script maintainability in Selenium?
How can you verify whether a CSS Selector correctly identifies an element before using it in Selenium?
I suspect this is due to a bug in cssQuery, which Selenium currently uses to locate elements by CSS. Details of the issue and a patch can be found in the comments of the following issue: http://jira.openqa.org/browse/SEL-698
Hope that helps - I believe Selenium 2 will be using a different library for CSS locators - possibly JQuery's Sizzle (http://sizzlejs.com/), which should solve this problem.
Dave.
To avoid painful CSS issues like this, I've installed jQuery as a user extension. It gives the ability to define a locator String similar to CSS ("jquery=td.dt-col-status div.dt-liner:contains('Complete')") that is much more powerful. I can expand on how I did it for the Java RC if you'd like.