This is the entire CSS that I used to center the lower menu bar on the Pitch theme. Originally it didn’t support child themes, so I made changes to the actual code. I’m working on updating with a child theme, which would actually be your best option. Good luck.
/* =Main Menu
————————————————————– */
#mainmenu {
margin: 10px 0;
margin-bottom: 0;
word-wrap: break-word;
}
ul#mainmenu-menu {
height: 42px;
background: rgb(247,247,247);
background: -moz-linear-gradient(top, rgba(247,247,247,1) 0%, rgba(244,244,244,1) 100%);
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(247,247,247,1)), color-stop(100%,rgba(244,244,244,1)));
background: -webkit-linear-gradient(top, rgba(247,247,247,1) 0%,rgba(244,244,244,1) 100%);
background: -o-linear-gradient(top, rgba(247,247,247,1) 0%,rgba(244,244,244,1) 100%);
background: -ms-linear-gradient(top, rgba(247,247,247,1) 0%,rgba(244,244,244,1) 100%);
background: linear-gradient(top, rgba(247,247,247,1) 0%,rgba(244,244,244,1) 100%);
border: 1px solid #E2E2E2;
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr=’#f7f7f7′, endColorstr=’#f4f4f4′,GradientType=0 );
text-align: center;
}
ul#mainmenu-menu li.menu-item {
position: relative;
display: inline-block;
font-size: 12px;
font-weight: bold;
}
ul#mainmenu-menu li.menu-item a {
color: #5e5e5e;
display: block;
padding: 15px 20px;
text-decoration: none;
}
ul#mainmenu-menu li.menu-item a:hover {
background: #C9C9C9;
}
ul#mainmenu-menu ul.sub-menu {
position: absolute;
top: 42px;
left: 0px;
width: 160px;
background: white;
border: none;
box-shadow: 0 1px 2px rgba(0,0,0,0.25);
display: none;
z-index: 99;
}
ul#mainmenu-menu li:hover ul.sub-menu {
display: block;
}
ul#mainmenu-menu ul.sub-menu li {
border: none;
font-weight: normal;
}
ul#mainmenu-menu ul.sub-menu li a {
line-height: 15px;
padding: 15px 15px 15px 15px;
}