CSS2.1 Conformance Test Suite

This is a version of the CSS2.1 Test Suite.

It contains unreviewed tests and should not be used for testing CSS conformance. This build exists to aid in test development only. Please check the latest version of the CSS2.1 specification and the errata list before assuming a failure is due to an implementation bug and not a test suite bug.

In time we hope to correct all errors and extend this test suite to cover all of CSS2.1. Your help is welcome in this effort. The appropriate mailing list for submitting tests and bug reports is public-css-testsuite@w3.org. More information on the contribution process and test guidelines is available on the wiki page.

Tests are currently available in three formats:

XHTML 1.1 tests sent as application/xhtml+xml
HTML 4.01
HTML 4.01 tests sent as text/html
XHTML 1.1 for Printers
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.

Note that many of the tests require the Ahem font to be installed. Without the Ahem font installed, these tests are of no value.

Common Assumptions

Most of the test suite makes the following assumptions:

Uncommon Assumptions

In addition, some of the tests make one or more of the following assumptions:

The tests that need these assumptions to be true have not yet been marked, but it is likely that we will add a way to identify these tests in due course.


This test suite is licensed under both the W3C Test Suite License and the W3C 3-clause BSD License. See W3C Legal's explanation of the licenses.


Many thanks to the following for their contributions:

...and all the contributors to the CSS1 test suite.