Whilst invetstigating transparent borders for IE5.x and IE6 and producing the previous demonstration, I came across the fact that IE7 has a different interpretation of transparent borders to all the other browsers that understand border transparency.
If you are viewing the above demonstration in any browser but IE you will see a rectangle with a transparent top border showing the grey background color under the transparent border.
If you are viewing this in IE5.x or IE6 you will see a black top border as these browsers are unable to style transparent borders and just use the foreground color.
However, if you are using IE7 then you note that the background color does not extend under the borders and you will see the background image of the containing 'outer' div. through the top transparent border.
Whilst I have no doubt that Firefox and the rest are correct, I do like the IE7 version better.
IE8 get it right and has the background color extending to the top of the rectangle.
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