Background image black in Konqueror

[Charles A. Landemaine]

I designed a standard-compliant mockup for PC-BSD's web site. The page
is displayed properly in the following browsers:

 - IE7
 - Opera 9
 - FF2
 - Seamonkey

But when I open it in Konqueror 3.5.5, the upper part of the page
where there is a grey gradient used as a background, is all black:
http://dev.pcbsd.org/site/

The page is valid:
http://validator.w3.org/check?uri=http%3A%2F%2Fdev.pcbsd.org%2Fsite%2F
http://jigsaw.w3.org/css-validator/validator?uri=http%3A%2F%2Fdev.pcbsd.org%2Fsite%2Fstyle.css&warning=1&profile=css21&usermedium=all

It may be a Konqueror bug. How could I circumvent this problem?
Thanks,

-- 
Charles A. Landemaine.