Hi Andy,
If you want to resize to like 140px, you need to replace some tag in file template_css.css of template:
1. You decrease width of side bar:
<blockquote>
#ja-sidecol {
width: 140px; <– 190px
float: right;
margin-bottom: 10px;
}
</blockquote>
2. You increase width of content:
<blockquote>
#ja-content {
width: 588px; <– 538px
float: left;
}
</blockquote>
3. Decrease width of text box:
<blockquote>
#mod_login_password, #mod_login_username {
width: 100px; <– 140px
}
</blockquote>
4. Set again property h3.
<blockquote>
background: url(../images/h3-bg.gif) bottom left no-repeat #E1E1E1;
</blockquote>
5. Resize width of content ( Wide layout )
<blockquote>
.wide #ja-content {
width: 738px; <– 688px
float: left;
}
</blockquote>
6. You copy overwrite two images main-bg.gif and main-wide-bg.gif in images folder. You can download two images at: http://www.joomlart.com/images/support/img_zibal.zip
wish success !