right navigation problem

https://www.sketchygrid.com
for some reason my right navigation bar bleeds over into my left. Everything within my second widget div class is moved over like there isn’t enough space but i never specified the hieght and when i do it screws everything up. I’ve also tried adding a div that clears but that just pushes stuff all around the page. I can’t figure out why.

<!-- begin sidebar right -->
<div class="sidemain">

<ul>

<?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar(1) ) : ?>

<div class="widget">
<div class="widget_top">
<h3>Sponsored Links</h3></div><!--/.widget_top-->
<div class="widget_center">
<!--Stuff-->
</div>
<div class="widget_bottom"></div><!--/.widget_bottom-->
</div><!--/.widget-->

<div class="widget">
<div class="widget_top">
<h3>Bookmarks</h3></div>
<?php wp_list_bookmarks('title_li=&categorize=0' ); ?>
<div class="widget_bottom"></div><!--/.widget_bottom-->
</div><!--/.widget-->

<?php endif; ?>

</ul>

</div>

<!-- end sidebar -->

.widget {
	width: 180px;
	background-color: #0F0;
	margin-left: 10px;
	float: left;
}

.widget_top {
	width: 180px;
	background-color: #00F;
	float: left;
}

.widget_bottom {
	width: 180px;
	background-color: #FF0;
	float: left;
}
.widget_center{
	padding-right: 10px;
}