如何在使用CSS的同时使导航栏链接居中，同时保持侧面为灰色？

Question

How do I center my navigation bar links using CSS while keeping the sides grey?

Blogs and History have a drop a down menu. Here is a screenshot:

_{(source: gyazo.com )}

CSS:

.navbar ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

.navbar li {
    float: left;
    width: 100px;
    background-color: #444444;
    text-align: center;
    border-right: 1px solid white;
    position: relative;
    height: 30px;
    line-height: 30px;
}

.navbar li ul li {
    float: none;
    width: 150px;
    text-align: left;
    padding-left: 5px;
    border-top: 1px solid white;
}

.navbar a {
    text-decoration: none;
    color: white;
}

.navbar li ul {
    position: absolute;
    top: 30px;
    left: 0;
    visibility: hidden;
}

.navbar li:hover ul {
    visibility: visible;
}

.navbar li:hover {
    background-color: maroon;
}

Answer 1

Edited my answer.. I've made your Container div clear the float, and set a defined width to navbar.

http://jsfiddle.net/jFdhM/

#container {
    border-radius: 10px;
    box-shadow: 3px 3px 4px;
    padding: 8px;
    background-color: #FFFFFF;
    width: 748px;
    margin: 0 auto;
}
#top {
    width: 748px;
}
.navbar {
    width: 505px;
    margin:0 auto;
}
.navbar ul {list-style:none; padding:0; margin: 0 auto;text-align: center;}
.navbar li {float:left; width:100px; background-color:#444444; text-align:center;
         border-right:1px solid white; position:relative;
         height:30px; line-height:30px;}
.navbar li ul li {float:none; width:150px; text-align:left; padding-left:5px;
         border-top:1px solid white;}
.navbar a {text-decoration:none; color:white;}
.navbar li ul {position:absolute; top:30px; left:0; visibility:hidden;}
.navbar li:hover ul {visibility:visible;}

.navbar li:hover {background-color:maroon;}

#maincontent {
    clear: both;
    padding: 10px;
    font-family: "Microsoft Sans Serif";
    font-size: medium;
}