CSS1 Test Suite
- Historical W3C CSS tests
- A hodgepodge of tests and examples, some of which made their way into the official Test Suite.
- NIST CSS test pages
- Neither for the faint of heart nor the impatient of mind, these tests are nonetheless an amazing resource.
- CSS Pointers Group
- A good collection of links to tips, tricks, tutorials, and other resources, all managed by CSS mavens Sue Sims and Jan Roland Eriksson.
- The primary newsgroup for stylesheet authors. If the residents here don't know the answer, you've probably found something new. Note: in order for this link to work, you'll need a newsreader with access to a server that carries the group.