Боксы рядом должны плавать влево, а затем за ними должен стоять прозрачный элемент.
Вот, пожалуйста,
<style>
html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, font, images, ins, kbd,q, s, samp, small, strike, strong, sub, sup, tt, var, dl, dt, dd, ol, ul, li, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td { margin: 0; padding: 0; border: 0; outline: 0; font-weight: inherit; font-style: inherit; font-size: 100%; font-family: inherit; vertical-align: baseline; }
body {
background-color: #c0cdd7;
color: #444444;
background-repeat: no-repeat;
margin: 0px;
padding: 0px;
text-align: left;
font: normal normal 13px Arial, 'Lucida Grande', Verdana, Sans-Serif;
}
div {
border: 1px solid red;
margin:-1px;
}
.wrapper {
width: 960px;
margin-left: auto;
margin-right: auto;
}
#logo {
position: absolute;
background-color: white;
margin-left: 30px;
z-index: 10;
background-position: 0px 0px;
background-repeat: no-repeat;
background-image: url(../images/logo.gif);
height: 100px;
width: 300px;
}
#header {
background-color: white;
height: 50px;
text-align: right;
width: 100%;
}
#navigation {
margin-left: 330px;
position: absolute;
margin-right: 30px;
font-weight: bold;
letter-spacing: 1px;
word-spacing: 5px;
font-size: 11px;
color: #6caddf;
margin-top: 25px;
text-transform: uppercase;
text-align: right;
padding-bottom: 5px;
padding-top: 5px;
width: 600px;
}
#navigation li {
padding-left: 10px;
padding-right: 10px;
border-right-color: #cccccc;
border-right-width: 1px;
border-right-style: solid;
list-style-type: none;
display: inline;
}
#navigation li.last {
border-right-style: none;
list-style-type: none;
}
#navigation li.active a {
font-weight: bold;
color: #6caddf;
list-style-type: none;
}
#mainImage {
position: relative;
height: 400px;
width: 960px;
z-index: 1;
margin-top: 0px;
background-color:red;
}
#content {
position: relative;
padding: 30px;
margin-top: -60px;
width: 840px;
margin-left: 30px;
margin-right: 30px;
background-color: white;
z-index: 15;
}
#content .col1 {
text-overflow: ellipsis;
z-index: 0;
width: 250px;
background-color:red;
float:left;
border:0;
height:300px;
}
#content .col2 {
z-index: 0;
width: 570px;
background-color:green;
float:left;
margin-left:20px;
border:0;
height:300px;
}
#footer {
border-top-color: #888888;
border-top-width: 1px;
border-top-style: dotted;
color: #888888;
padding: 30px;
clear: both;
}
#copyright {
color: #888888;
padding: 30px;
clear: both;
text-align: left;
font-size: 9px;
}
.clr {clear:both;}
</style>
<div id="header">
<div class="wrapper">
<div id="logo"></div>
<ul id="navigation">
<li><a href="#">Item</a></li>
<li><a href="#">Item</a></li>
<li><a href="#">Item</a></li>
<li><a href="#">Item</a></li>
</ul>
</div>
</div>
<div class="wrapper">
<div id="mainImage"></div>
<div id="content">
<div class="col1"> </div>
<div class="col2"> </div>
<div class="clr"></div>
</div>
<div id="footer"></div>
<div id="copyright"></div>
</div>
Код все еще грязный, но ваша проблема была решена.