Center Align Navigation Bar - html

Question

I'm having a hard time centering the navigation bar I've created.
HTML Code:
<div class="menu">
<ul>
<li>Home</li>
<li>About Mr. A</li>
<li>Intro
<ul>
<li>Daily Agenda</li>
<li>Handouts</li>
<li>Student Work</li>
</ul>
</li>
<li>Digital Design
<ul>
<li>Daily Agenda</li>
<li>Handouts</li>
<li>Student Work</li>
</ul>
</li>
<li>Web Design
<ul>
<li>Daily Agenda</li>
<li>Handouts</li>
<li>Student Work</li>
</ul>
</li>
<li>AP Computer Science
<ul>
<li>Daily Agenda</li>
<li>Handouts</li>
</ul>
</li>
<li>FBLA
<ul>
<li>Membership</li>
<li>Competitions</li>
<li>Conferences</li>
</ul>
</li>
</ul>
</div>
</body>
CSS Code:
html {
background-color:#2f2f4f;
}
div {
position:relative;
}
.menu {
position:absolute;
}
.menu ul {
padding:0;
margin:0;
line-height:30px;
}
.menu li {
position:relative;
float:left;
list-style:none;
border-bottom-style:solid;
border-top-style:solid;
border-color:#c5b358;
border-width:1px;
}
.menu ul ul {
position:absolute;
visibility:hidden;
padding:0;
margin:0;
}
.menu ul li a {
text-align:center;
font:"Georgia", serif;
font-size:18px;
color:#c5b358;
width:250px;
height:50px;
display:table-cell;
text-decoration:none;
vertical-align:middle;
}
.menu ul li:hover {
background-color:#2f4f2f;
text-decoration:none;
}
.menu ul li:hover ul {
visibility:visible;
z-index:1;
}
.menu ul li:hover ul li a {
background:#2f4f2f;
z-index:1;
border-bottom:none;
opacity:0.9;
text-decoration:none;
}
.menu ul li ul li:hover {
background:#2f4f2f;
opacity:0.8;
text-decoration:underline;
}
Nothing I do seems to work. I've tried several different options and can't find a solution. I'm fairly new to web design and it took me a while to get to this point.

Answer 1

I am expecting that I understood your question correctly. and on that basis I have modified your css code to get the desired result. please check the fiddle:https://jsfiddle.net/nileshmahaja/0k76hxc1/
Modified CSS
.menu ul {
text-align:center; /* Added */
}
.menu li {
/*float:left; Removed */
display:inline-block; /* Added */
}