Spry Menu - getting it to go fully across the page

Question

Hi Everyone,
I'm making pretty good progress with DW CS4 to create my own business website, using a MacBook Pro. I've created a Spry Horizontal Menu Bar on the homepage, and have managed to get it how I want it to look (colours, position etc.) except that I would like the menu to go across the whole width of page. At the moment it leaves a small gap at the right of the menu which looks unprofessional. I had to change the font size to 95% so that the menu doesn't extend onto another line, but I just can't get it to fit exactly the 46em page width. (I am not using any submenus).
Here is the code below. Would be very grateful for any help.
Justin
@charset "UTF-8";
/* SpryMenuBarHorizontal.css - version 0.6 - Spry Pre-Release 1.6.1 */
/* Copyright (c) 2006. Adobe Systems Incorporated. All rights reserved. */
LAYOUT INFORMATION: describes box model, positioning, z-order
/* The outermost container of the Menu Bar, an auto width box with no margin or padding */
ul.MenuBarHorizontal
     margin: auto;
     padding: 0;
     list-style-type: none;
     font-size: 95%;
     cursor: default;
     width: auto;
     min-height: 1em;
/* Set the active Menu Bar with this class, currently setting z-index to accomodate IE rendering bug: http://therealcrisp.xs4all.nl/meuk/IE-zindexbug.html */
ul.MenuBarActive
     z-index: 1000;
/* Menu item containers, position children relative to this container and are a fixed width */
ul.MenuBarHorizontal li
     margin: 0;
     padding: 0;
     list-style-type: none;
     font-size: 100%;
     position: relative;
     text-align: left;
     cursor: pointer;
     width: auto;
     float: left;
     white-space: nowrap
/* Submenus should appear below their parent (top: 0) with a higher z-index, but they are initially off the left side of the screen (-1000em) */
ul.MenuBarHorizontal ul
     margin: 0;
     padding: 0;
     list-style-type: none;
     font-size: 100%;
     z-index: 1020;
     cursor: default;
     width: auto;
     position: absolute;
     left: -1000em;
/* Submenu that is showing with class designation MenuBarSubmenuVisible, we set left to auto so it comes onto the screen below its parent menu item */
ul.MenuBarHorizontal ul.MenuBarSubmenuVisible
     left: auto;
/* Menu item containers are same fixed width as parent */
ul.MenuBarHorizontal ul li
     float: none;
     background-color: transparent;
/* Submenus should appear slightly overlapping to the right (95%) and up (-5%) */
ul.MenuBarHorizontal ul ul
     position: absolute;
     margin: -5% 0 0 95%;
/* Submenu that is showing with class designation MenuBarSubmenuVisible, we set left to 0 so it comes onto the screen */
ul.MenuBarHorizontal ul.MenuBarSubmenuVisible ul.MenuBarSubmenuVisible
     left: auto;
     top: 0;
DESIGN INFORMATION: describes color scheme, borders, fonts
/* Submenu containers have borders on all sides */
ul.MenuBarHorizontal ul
     border: none;
/* Menu items are a light gray block with padding and no text decoration */
ul.MenuBarHorizontal a
     display: block;
     cursor: pointer;
     background-color: #83B02B;
     padding: 0.5em 1.54em;
     color: #FFFFFF;
     text-decoration: none;
/* Menu items that have mouse over or focus have a blue background and white text */
ul.MenuBarHorizontal a:hover, ul.MenuBarHorizontal a:focus
     background-color: #E50000;
     color: #FFF;
     font-size: 100%;
/* Menu items that are open with submenus are set to MenuBarItemHover with a blue background and white text */
ul.MenuBarHorizontal a.MenuBarItemHover, ul.MenuBarHorizontal a.MenuBarItemSubmenuHover, ul.MenuBarHorizontal a.MenuBarSubmenuVisible
     background-color: #E50000;
     color: #FFF;
#here { background-color: #7F7F7F; }
SUBMENU INDICATION: styles if there is a submenu under a given menu item
/* Menu items that have a submenu have the class designation MenuBarItemSubmenu and are set to use a background image positioned on the far left (95%) and centered vertically (50%) */
ul.MenuBarHorizontal a.MenuBarItemSubmenu
     background-image: url(SpryMenuBarDown.gif);
     background-repeat: no-repeat;
     background-position: 95% 50%;
     font-family: Verdana, Arial, sans-serif;
/* Menu items that have a submenu have the class designation MenuBarItemSubmenu and are set to use a background image positioned on the far left (95%) and centered vertically (50%) */
ul.MenuBarHorizontal ul a.MenuBarItemSubmenu
     background-image: url(SpryMenuBarRight.gif);
     background-repeat: no-repeat;
     background-position: 95% 50%;
/* Menu items that are open with submenus have the class designation MenuBarItemSubmenuHover and are set to use a "hover" background image positioned on the far left (95%) and centered vertically (50%) */
ul.MenuBarHorizontal a.MenuBarItemSubmenuHover
     background-image: url(SpryMenuBarDownHover.gif);
     background-repeat: no-repeat;
     background-position: 95% 50%;
/* Menu items that are open with submenus have the class designation MenuBarItemSubmenuHover and are set to use a "hover" background image positioned on the far left (95%) and centered vertically (50%) */
ul.MenuBarHorizontal ul a.MenuBarItemSubmenuHover
     background-image: url(SpryMenuBarRightHover.gif);
     background-repeat: no-repeat;
     background-position: 95% 50%;
BROWSER HACKS: the hacks below should not be changed unless you are an expert
/* HACK FOR IE: to make sure the sub menus show above form controls, we underlay each submenu with an iframe */
ul.MenuBarHorizontal iframe
     position: absolute;
     z-index: 1010;
     filter:alpha(opacity:0.1);
/* HACK FOR IE: to stabilize appearance of menu items; the slash in float is to keep IE 5.0 from parsing */
@media screen, projection
     ul.MenuBarHorizontal li.MenuBarItemIE
          display: inline;
          f\loat: left;
          background: #FFF;

Answer 1

Justin,
I had the exact same question a few days ago.  I did what Ben suggested at first.  I wrapped the entire menu (or ul) in a div and applied an id with a bgcolor the same as the menu.  I was totally dumbfounded when it wouldn't span the entire page.  I div should be a block element and therefore span edge of the page.  I then set the width of the div trying to get it to go across the full 1000 pixel space I wanted covered.  Still nothing!
Then I had an insight.  The styles on the ul that build the menu position is absolutely, with basically takes it out of the page flow.  Have you ever seen a div with nothing it in...no you  haven't because they always collapse, just like an empty td.  Sooo, I went back and set the HEIGHT of the div and removed the width and guess what?  It worked perfectly.  I did have to set the height in ems and played around with it as I decreased the font size of the menu.  Currently my menu is set to 80% in the .MenuBarHorizontal and my background div is set to 1.8 ems.
To sum up:
1.     Wrap the menu in a div with some id (or class) applied to it.
<div id="navbg">
    <ul id="MenuBar1" class="MenuBarHorizontal">
    </ul>
</div>
2.     Build an id (or class) that sets the bgcolor and height
#navbg {
            background-color: #23A6DC;
            height: 1.8em; (because my menu is at 80%, otherwise 2 em seemed to work fine)
DONE!