unable to centralize dropdownmenu using CSS - css

Question

I know there are many posts on centralizing a drop down menu. However, after trying all the various solutions, it seems that I'm still missing something. I got the code of a dropdownmenu from some free website as follows:
#nav {
margin: 0;
padding: 7px 6px 0;
line-height: 100%;
border-radius: 2em;
-webkit-border-radius: 2em;
-moz-border-radius: 2em;
-webkit-box-shadow: 0 1px 3px rgba(0, 0, 0, .4);
-moz-box-shadow: 0 1px 3px rgba(0, 0, 0, .4);
background: #000080; /* for non-css3 browsers */
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#3090C7', endColorstr='#000080'); /* for IE */
background: -webkit-gradient(linear, left top, left bottom, from(#3090C7), to(#000080)); /* for webkit browsers */
background: -moz-linear-gradient(top, #3090C7, #000080); /* for firefox 3.6+ */
border: solid 1px #6d6d6d;
}
#nav li
{
margin: 0 5px;
padding: 0 0 8px;
float: left;
position: relative;
list-style: none;
}
/* main level link */
#nav a {
font-weight: bold;
color: #e7e5e5;
text-decoration: none;
display: block;
padding: 8px 20px;
margin: 0;
-webkit-border-radius: 1.6em;
-moz-border-radius: 1.6em;
text-shadow: 0 1px 1px rgba(0, 0, 0, .3);
}
/* main level link hover */
#nav .current a, #nav li:hover > a {
background: #d1d1d1; /* for non-css3 browsers */
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ebebeb', endColorstr='#a1a1a1'); /* for IE */
background: -webkit-gradient(linear, left top, left bottom, from(#ebebeb), to(#a1a1a1)); /* for webkit browsers */
background: -moz-linear-gradient(top, #ebebeb, #a1a1a1); /* for firefox 3.6+ */
color: #444;
border-top: solid 1px #f8f8f8;
-webkit-box-shadow: 0 1px 1px rgba(0, 0, 0, .2);
-moz-box-shadow: 0 1px 1px rgba(0, 0, 0, .2);
box-shadow: 0 1px 1px rgba(0, 0, 0, .2);
text-shadow: 0 1px 0 rgba(255, 255, 255, .8);
}
/* sub levels link hover */
#nav ul li:hover a, #nav li:hover li a {
background: none;
border: none;
color: #666;
-webkit-box-shadow: none;
-moz-box-shadow: none;
}
#nav ul a:hover {
background: #0399d4 !important; /* for non-css3 browsers */
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#04acec', endColorstr='#0186ba'); /* for IE */
background: -webkit-gradient(linear, left top, left bottom, from(#04acec), to(#0186ba)) !important; /* for webkit browsers */
background: -moz-linear-gradient(top, #04acec, #0186ba) !important; /* for firefox 3.6+ */
color: #fff !important;
-webkit-border-radius: 0;
-moz-border-radius: 0;
text-shadow: 0 1px 1px rgba(0, 0, 0, .1);
}
/* level 2 list */
#nav ul {
background: #ddd; /* for non-css3 browsers */
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffff', endColorstr='#cfcfcf'); /* for IE */
background: -webkit-gradient(linear, left top, left bottom, from(#fff), to(#cfcfcf)); /* for webkit browsers */
background: -moz-linear-gradient(top, #fff, #cfcfcf); /* for firefox 3.6+ */
display: none;
margin: 0;
padding: 0;
width: 185px;
position: absolute;
top: 35px;
left: 0;
border: solid 1px #b4b4b4;
-webkit-border-radius: 10px;
-moz-border-radius: 10px;
border-radius: 10px;
-webkit-box-shadow: 0 1px 3px rgba(0, 0, 0, .3);
-moz-box-shadow: 0 1px 3px rgba(0, 0, 0, .3);
box-shadow: 0 1px 3px rgba(0, 0, 0, .3);
}
/* dropdown */
#nav li:hover > ul {
display: block;
}
#nav ul li {
float: none;
margin: 0;
padding: 0;
}
#nav ul a {
font-weight: normal;
text-shadow: 0 1px 1px rgba(255, 255, 255, .9);
}
/* level 3+ list */
#nav ul ul {
left: 181px;
top: -3px;
}
/* rounded corners for first and last child */
#nav ul li:first-child > a {
-webkit-border-top-left-radius: 9px;
-moz-border-radius-topleft: 9px;
-webkit-border-top-right-radius: 9px;
-moz-border-radius-topright: 9px;
}
#nav ul li:last-child > a {
-webkit-border-bottom-left-radius: 9px;
-moz-border-radius-bottomleft: 9px;
-webkit-border-bottom-right-radius: 9px;
-moz-border-radius-bottomright: 9px;
}
/* clearfix */
#nav:after {
content: ".";
display: block;
clear: both;
visibility: hidden;
line-height: 0;
height: 0;
}
#nav {
display: inline-block;
margin-left: 15%;
margin-top: 20px;
}
html[xmlns] #nav {
display: block;
}
* html #nav {
height: 1%;
}
I tried to embed the menu with div having style of using margin-left and margin-right as auto but it still could not work probably due to the use of float:left.
Sorry if it this question seems repeated. I'm still new to CSS so I hope some kind soul can help me out here! Thanks!

Answer 1

Try:
#nav {
margin: 0;
}
#menu {
text-align: center;
}
Your updated fiddle.

Answer 2

not sure what the desired effect is, but using your #menu style, you can move that nav wherever you want:
#menu {
width:600px;
height:50px;
background-color:red;
padding-left:10px;
}
I just did a background color so you can see where your nav is in relation to the div. Post any other HTML you have so I can make changes if this isn't what you want.