Shadow-looking border at the sides of a page

[WebEmperess]

Hello all you there, Im currently working on a website for my youth company's webpage (school project). The theme is rather white & blue and therefor I'd like to know how others create that shadowy design to the right & left of a page.

I apologise for my poor English.

Here is a link on what I mean (look at the sides of the white main-content - its black/shadowy).

http://www.welive.se/

Is it even a CSS matter? perhaps its graphical? like a bakground where they have designed it to be shadow-looking just next to the actual page? I don't know but would really like to :o

Thanks in advance!

[KDLA]

They use two background images:
http://www.welive.se/templates/ja_drimia/images/shadow-right.gif
http://www.welive.se/templates/ja_drimia/images/shadow-left.gif

Then create two divs:
#ja-wrapper2 {
background: url(../images/shadow-left.gif) repeat-y top left;
padding-left: 15px;
}

#ja-wrapper3 {
background: url(../images/shadow-right.gif) repeat-y top right;
padding-right: 15px;
}

which are nested:

<div id="ja-wrapper2">
<div id="ja-wrapper3">
...
</div>
</div>

[WebEmperess]

Thanks alot I will try it =)