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Fix 'r.p. punch' by changing:

Content box
Remove position:relative.
Inner floats
Remove float from either.
Clearer
Remove clearing element from HTML below inner floats.
 

Disappearing content in IE 7b2 - 'r.p. punch'

If you can see anything here, you probably aren't using Internet Explorer 7.

The content box in the middle has position:relative, originally for IE6, and also partly to position a box within it at the bottom.

The floated elements in the middle seem to trigger the peekaboo bug, a new bug in IE 7, in combination with the parents relative position.

Ingo Chao wrote it up in IE/Win: relatively positioned parent and floated child - disappearance.

This is the minimal version, with only enough element and CSS to trigger the bug. The original test case is probably better to test with once it has been fixed here.