100%-10px?

There are a few scenarios to consider here. If you have a fixed width layout, then you'll probably have a wrapper div set to hold all of the content, the meat of the site. In this case, you would specify this rule on the div in question:

#yourdiv { margin-right: 10px; }

This would push #yourdiv 10 pixels away its parent edge. If your layout is a liquid and spans the whole page, you won't know the exact width in pixels, so you could set your margin at the body level.

body { padding: 0; margin-right: 10px; }

Without knowing the kind of layout you've chosen, it's pretty tough to give you a single answer. Hopefully this has given you a slightly better understanding.

Antibland

i've tried that, but it doesn't work...... in the box model the padding and margin are outside the measurements of the widht.... so adding a 10px margin wouldn't move it at all... take a look at this diagram:

Don't specify a width. The default behavior for a block level elements is to take all the available width. If you do {margin-right: 10px;}, the element will be 100%-10px wide. That's just The Way Things Work.

cheers,

gary

thanx for the replies and it really worked like you said... however when i tried to apply it to the layout i'm creating i ran into a lot of issues and couldn't figure it out after an hour of trying... i would really appreciate it if you told me how can i accomplish my layout... here's a pic of wat i want to do:

thank you....

This should do it.

CSS - 
#holder{}
#green {margin-right: 350px}
#red {float:right; width:250px;}
#blue {float:right; width:100px;}

* html #green {height:1%}   /* to get IE into its box model */

HTML -
<div id='holder'>
  <div id='red'> red content</div>
  <div id='blue'>blue content</div>
  <div id='green'> the rest</div>
</div>

If you need holder to wrap around the three divs, then checkout http://www.positioniseverything.net/easyclearing.html

If you want a background to make it look like each column is extending the full length of the longest column, then checkout http://www.alistapart.com/articles/fauxcolumns/