farsite281 on "[Plugin: Jetpack by WordPress.com] Jetpack CSS overriding Custom CSS"

I have the same problem. I tried to add

#content .slideshow-window, .jetpack-slideshow {
background-color: #FFFFFF;
}

to change de the styling of background of slideshow (#000000 - #FFFFFF) but background is still black instead of white.

http://wp.me/p3sPNo-k

I use Athaualpa theme.

Any idea without modifying the css file?

Thank you!