CSS Selector Shell Released

By Lindsey Simon, Google User Experience Team

Most web developers have felt the pain of discovering or remembering ways in which different browsers interpret and/or render their Cascading Style Sheets (CSS). Our newly released CSS Selector Shell is a simple Javascript tool for testing how a given browser parses CSS text by inserting a style element into the document and then reading the cssText back programmatically. You can already check out the CSS Selector Shell code base in action on Google AppEngine.

So far this tool has proven quite useful by showing what happens when developers try to make use of CSS selector syntax that may not be supported in a particular browser. Specifically, it can show how and perhaps why a particular CSS hack works in some browsers and how it is ignored in others. It can also demonstrate the potential for harm when using unsupported CSS syntax in some browsers. For instance, when testing a combined selector ".class1.class2" in Internet Explorer 6, it becomes active as ".class2", which may not at all be the goal of the CSS author. Another detail the CSS Selector Shell demonstrates is that shorthand property/values sometimes expand much further than you may have suspected. On the test page itself, there are two visible test elements that you can use to target and experiment. The code itself makes use of the Dojo Tooklit as well as the Django framework.

We hope this tool will be useful to you in diagnosing problems or understanding the differences between browsers when interacting with your Cascading Style Sheets. We always welcome your feedback, so check out the code and let us know what you think in our discussion group.