I assure you I tried to find it
I did that before too..but I'm kind of a newbie! So, I appreciate your help even more

I didn't know Firebug. I use Chrome so thank you for showing me this debugging which is much more simple and easy to read!
So the HTML is:
<body class="home page page-id-2 page-template-default">
<div id="wrapper">
<div id="container">
<table id="layout" cellspacing="0" cellpadding="0" border="0">
<colgroup>
<col class="coltwo">
</colgroup>
<tbody>
<tr>
<td id="header" colspan="1">
<div id="header1" class="bfa_widget_area">
<div id="widget_sp_image-2" class="widget widget_sp_image">
<img class="attachment-full" width="800" height="111" src="http://protocolos.mdsinsure.com/redunicre/files/2013/03/redunicre.png" style="max-width: 800px;max-height: 111px;" alt="">
</div>
</div>
<div class="horbar1"> </div>
<div id="menu1">
<ul id="rmenu2" class="clearfix rMenu-hor rMenu">
<li class="page_item page-item-2 current_page_item">
<a href="http://protocolos.mdsinsure.com/redunicre/">
<span>Home</span>
</a>
</li>
<li class="page_item page-item-23">
<a href="http://protocolos.mdsinsure.com/redunicre/subscricao-mr-comercio-servicos/">
<span>Subscrição MR Comércio & Serviços</span>
</a>
</li>
<li class="page_item page-item-25">
<a href="http://protocolos.mdsinsure.com/redunicre/subscricao-acidentes-de-trabalho/">
<span>Subscrição Acidentes de Trabalho</span>
</a>
</li>
</ul>
</div>
</td>
</tr>
And the style is:
.clearfix:after {
clear: both;
content: ".";
display: block;
height: 0;
visibility: hidden;
}
div#menu1 ul.rMenu {
background: none repeat scroll 0 0 #D1D0D0;
border: 1px none #D1D0D0;
}
ul.rMenu-hor {
padding-left: 1px;
}
ul.rMenu, ul.rMenu li, ul.rMenu ul {
list-style: none outside none;
}
ul.rMenu, ul.rMenu ul, ul.rMenu li, ul.rMenu a {
display: block;
margin: 0;
padding: 0;
}
.clearfix {
display: block;
min-width: 0;
}
ul, ol, dl, p, h1, h2, h3, h4, h5, h6 {
margin-bottom: 10px;
margin-top: 10px;
padding-bottom: 0;
padding-top: 0;
}