body {
margin: 0;
background: url(../img/fdo2.jpg) no-repeat left top;
font: 12px/14px Arial, Helvetica, sans-serif;
color: #333
}

#header {
width: 978px;
height: 158px;
padding: 10px 0 0 10px;
background: url(../img/trans.png) repeat left top;
position: absolute;
left: 0;
overflow: hidden;
margin-top: -64px;
top: 50%; 
}

#logo {
width: 336px;
height: 148px;
background: #000;
float: left;
diplay: inline;
margin: 0 10px 0 0;
 
}

#logo img {
display: block;
margin: 16px 0 0 21px
}

#header ul {
list-style: none;
margin: 0;
padding: 0;
}

#header ul li {
width: 148px;
height: 148px;
background: #000;
float: left;
display: inline;
margin: 0 10px 0 0;
}

#header ul li span {
display: none;
}

#header ul li a {
display: block;
width: 148px;
height: 148px;
}

#header ul li.servicios a {
display: block;
width: 148px;
height: 148px;
background: url(../img/tab-01ser.png) no-repeat 56px 96px;
_background: url(../img/tab-01ser.gif) no-repeat 56px 96px;

}

#header ul li.portfolio a {
display: block;
width: 148px;
height: 148px;
background: url(../img/tab-02port.png) no-repeat 56px 96px;
_background: url(../img/tab-02port.gif) no-repeat 56px 96px;
}

#header ul li.clientes a {
display: block;
width: 148px;
height: 148px;
background: url(../img/tab-03cli.png) no-repeat 56px 96px;
_background: url(../img/tab-03cli.gif) no-repeat 56px 96px;
}

#header ul li.contacto a {
display: block;
width: 148px;
height: 148px;
background: url(../img/tab-04cont.png) no-repeat 56px 96px;
_background: url(../img/tab-04cont.gif) no-repeat 56px 96px;
}

#header ul li.servicios a:hover {
background-color: #2ed118;
height: 158px;
}

#header ul li.portfolio a:hover {
background-color: #0098e8;
height: 158px;
}

#header ul li.clientes a:hover {
background-color: #ff0078;
height: 158px;
}

#header ul li.contacto a:hover {
background-color: #ffd800;
height: 158px;
}