Styling a Featurific plugin window

[fscinico]

On my homepage at http://www.scinico.org, I have a Featurific window 322w x 305h on the top-left side of the content area. The window has a 1px black border that I want to replace with a lighter blue one (color #B1C3D4). I asked the Featurific team how i can do that. This is what they replied:

The easiest thing to do is to remove the border entirely, and then add your own custom border. It's a bit complicated, though... You can edit your wordpress template so that Featurific appears within a <div> that is two pixels smaller than the Featurific slideshow in both dimensions (width and height). Then, when you center the contents of the <div> the border disappears, since it is only a one pixel border. Then, you can add your own border (by either styling the <div>, or adding a new <div> around the first <div>).

Any suggestions on how I could implement this?
Thank you very much,
Francesco