need top menu nav bar fixing, help!

Hi
Please see https://www.giuliojossa.com
The top nav bar is giving me grief, as you can see its all bunched together and not in line with the content below.

Code is as follows:

#top {
background: #ffffff;
border-bottom: 0px solid #ffffff;
height: 50px;
margin: 0 auto;
width:100%;
text-align: center;
overflow: hidden;
}

#topbar { height: 50px;
width:100%;
margin: 15px;
padding: 0;
text-align: center;
}

ul.topmenu {
background: transparent;
float: none;
margin: 0px 150px 0px 0px;
padding: 0;
list-style-type: none;
}

ul.topmenu li {
float: left;
}

ul.topmenu li a {
float: left;
display: block;
height: 50px;
padding: 0px 0px 0 0px;
color: #000000;
}

ul.topmenu li a:hover {
color: #000000;
text-decoration: bold;
}

any help greatly appreciated ??