IE7 Z-index problem

Problem site: www.basing.com/problem/index.html

If you hover over the items in the list on the left you should see a nice popup showing the remaining characters of the text.

However, this doesn't work in IE 7. Does anyone have any ideas why not, or suggestions开发者_StackOverflow中文版 on how I could go about fixing this? Thanks.

There is a known bug about z-index on IE <= 7, when you use z-index when you mix absolute and relative positionned DOM elements you have to invert the z-index properties so that the lower will appear on top of the higher.

See http://brenelz.com/blog/squish-the-internet-explorer-z-index-bug or http://www.shawnpreisz.com/css/z-index-internet-explorer-7-ie7 for another solution.

There is about a million post about this bug on the internet.