Cascading Style Sheets Working Group

W3C CSS 2.1 Conformance Test Harness

This is a development version of a test harness for conducting CSS 2.1 conformance testing using the CSS 2.1 Conformance Test Suite.

The W3C CSS 2.1 Conformance Test Harness, adapted from the Mobile Test Harness by the CSS WG (Cascading Style Sheets Working Group), provides navigation and results recording controls for assessing efficiently browser-based CSS test cases, allowing anyone to submit easily pass/fail data in CSS conformance testing.

Currently, you can provide test data or review the testing results for the following test suites:

XHTML 1.1 for Printers ( Enter Data , Review Results )
XHTML 1.1 tests with all images converted from PNG to JPEG and formatted with headers and footers to ease testing of embedded printer software. This is not a canonical format, and some tests may fail due to the format conversion that would otherwise pass in the above XHTML 1.1 format.
XHTML 1.1 ( Enter Data , Review Results )
XHTML 1.1 tests sent as application/xhtml+xml
HTML 4.01 ( Enter Data , Review Results )
HTML 4.01 tests sent as text/html

Note that many of the tests require the client to be properly configured. For example, many of the tests require the Ahem font to be installed. For a particular test any specific client requirements will be noted by the harness interface. Tests on clients not meeting listed configuration requirements are of no value

Developed and maintained by:
Dominique Hazael-Massieux (
David M. Berfanger (