O.o Canary, huh? Odd as it works in the stable version of Chrome and is done using a z-index... you sure this isn't an issue with Canary itself? I will look into it and try to fix it. Thanks for the bug report either way, and thanks for the compliments.
And I feel I must apologize for the small width on your large monitor.
I don't have a monitor large enough to know... how often do you come across fixed-width small layouts? Again, I wasn't a part of the initial CSS process, so I didn't have a lot of control over that, but I <3 fluid layouts.