how to set a background image as width:100%

[suavedesign]

my url is http://www.chailifeline.org/events/letourdesimcha-new/index.php
How can i get the background image on top to stay as a full background border, no matter how much a user zoom out?
it's width is set as 100%. I dont want to see any black background when I zoom out. How do i do that?
my html:

<div class="top">
                <div class="padding">
                <div class="buttons">
            <div class="but first"><a href="mt-register">Register</a></div>
            <div class="but"><a href="sponsors.php">Sponsor</a></div>
            <div class="clear"></div>
                </div><!--end buttons-->

                </div><!--end padding-->
        </div><!--end top-->

my css:

#home .top{
    background: url(images/home_top.jpg) no-repeat;
    width:100%;
}

#home .padding{
    width:1200px;
    margin:0 auto;
}

thank you

[minitauros]

Have you tried what has been posted here (StackOverflow)?

[suavedesign]

thanks, that helped!