Centering navmenu within a div

Centering navmenu within a div

I have a drop down nav menu that I need to be centered within a div but
text-align: center isn't working for me.
The site is at http://www.joekellywebdesign.com/churchsample1/index.html
<div id="navmenudiv">
`<ul id="navmenu">`
`<li><a href="index.html">Home</a></li>`
`<li><a href="about.html">About Us</a>`
`<ul class="sub1">`
`<li><a href="introduction.html">Introduction</a></li>`
` <li><a href="whoweare.html">Who We Are</a></li>`
`<li><a href="staff.html">Staff</a></li>`
`</ul>`
`</li>`
`<li><a href="services.html">Services</a>`
`<ul class="sub1">`
`<li><a href="sundaymorning.html">Sunday
Morning</a></li>`
`<li><a href="sundayevening.html">Sunday
Evening</a></li>`
`<li><a href="wednesday.html">Wednesday Evening</a></li>`
`</ul> `
`</li>`
`<li><a href="resources.html">Resources</a></li>`
`<li><a href="contact.html">Contact Us</a></li>`
`<li><a href="news.html">News and Events</a></li>`
`</ul>`
`</div>`
The css is at http://www.joekellywebdesign.com/churchsample1/css/styles.css
navmenudiv {
z-index:60;
margin: -30px 0;
height:50px;
background-color:#5340BF;
top:40;position:
relative;
text-align:center;
}