absolute positioning with bottom doesn't work. I just revised my test (there were some serious errors). I don't think it did anything on the old version either, but I'm not sure. However, the new version should be correct (I was missing needed margin-top: auto 's).

Here's why I think the test is wrong. Take this part of the test, for example: <div class="contain abs"> <p class="six">This paragraph should be 70px high and has 50px below it and 30px above it.</p> </div> Even though you want the P to have a 'margin-top' of 'auto': p.six { position: absolute; bottom: 50px; height: 70px; margin-top: auto; } It doesn't, because this rule has a higher specificity and so the computed 'margin-top' is 0: div.contain p { background-color: yellow; margin: 0 20px; padding: 0; border: none; }

Yup. Verified invalid. Sorry. You mentioned that before, and for some reason I fixed it on only one of the 4 tests. It should be OK now.