This report was prepared to document the current implementation status of the CSS Basic User Interface Module Level 3 (CSS User Interface 3) specification as of 19 September 2018 and is based on current test results available in the W3C Conformance Test Harness.
Ten user agents, built from six rendering implementations, were tested across six operating systems.
The 19 September 2018 revision of the CSS User Interface 3 test suite was used. The test suite consists of 257 tests, 34 of which test for optional behavior.
These tests are available in several host language variants:
Some tests only apply to certain language variants; the results for each tested implementation are reported for each tested language variant. Also, not all tests are applicable to each implementation; for example, a browser which implements HTML but not XHTML is not tested for XHTML.
In summary, the results show that 213 of 223 tests for required behavior were passed by at least two of the tested implementations. In addition, 16 of 34 tests for optional behavior were passed by at least two of the tested implementations.
Results were gathered from implementation reports submitted by user agent vendors as well as the general public via the W3C Conformance Test Harness.