How can I have vertical lines on my site

i had a quick look at your html code and css. I suggest you add an extra <div> surrounding your right column parts. Put border on the left and right side of it and remove the borders of div with <div id="rightwide">

Thank you, but that is not unsimilar as to how its done now. If I put divs around these columns, they will only go as deep as the containing text, while I want the middle, main, column to dictate that length.

Actually for your website that's particularly easy. Since the .centerpage element already has overflow:hidden, yours is a perfect page to abuse an equal column technique with a padding/margin combination! See more: http://www.positioniseverything.net/articles/onetruelayout/equalheight

Example, add the following:
#left {
margin:0 0 -5000px;
padding:0 5px 5005px;
}

As you can see I kept the padding 5px larger than the negative margin, this is to keep the existing padding of 5px...

Sorry, I misunderstood you. Never scrolled down. I thought the problem was something else.
Now I know what you mean.

Maybe if you have a container under the header which covers your left, center and right columns and then set all the outer columns div height to 100% with a top and bottom margin to get some space up and down.

http://www.ejeliot.com/blog/61

@mreuring
Thanks: I managed to create the left line, but on the right side it is more complicated. I tried:

#right2 {
  background: #FFFFFF;
  color: #000000;
  float: left;
  padding: 0px 5px 5px;
  border-right: 1px solid #006600;
  font-family: Tahoma,Verdana,Arial,Helvetica,sans-serif;
  font-size: 1em;
  margin: 0;
  width: 158px;
  overflow: hidden;
}
  #right2 {
margin:0 0 -5000px;
padding:0 5px 5005px;
}


But it didnt produce anything.

You don't have an element with and ID of right2 in your site's theme.

Well, since you have no single right-hand element, picking up the first element and performing the same trick worked for me, in FF3.something, using firebug on OSX...

#right1 {
border-right:1px solid black;
margin:0 0 -5000px;
padding:0 0 5005px 5px;
width:325px;
}

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@mreuring: Thanks but  applying this setting also sets the block in region right1 at another  width (right1 is supposed to be 150, not the 325 you set here, right2 158)..
I have applied the setting to right2 where it works. Only on long pages it doesnt go to the bottom, not even after I change it to 15.000px and even 2500px (after clearing the cache). See www.groenerekenkamer.nl/windenergie

If I use the setting you supplied for right1 with its regular width (150px) than this is interpreted as the right end of the page (nothing thereafter is shown anymore).

So to summarise I manage line 1,2,3 and 5, though the latter is not long enough and how about line 4?