Horizontally align LI - html

Question

I've got 5 li on my page.
One of theme (the third) is higher than the other. I would like them to horizontally align to the center of this biggest LI. However, it's aligning on the top of it.
I've tried to use "Vertical-align: middle" but it doesn't work.
Here is my actual code:
<link rel="stylesheet" href="style2015.css" />
<div id="menu">
<ul>
<li>Portfolio
<ul>
<li>Sous-item 1</li>
<li>Sous-item 2</li>
<li>Sous-item 3</li>
</ul>
</li>
<li>Projets
</li>
<li id="logo"></li>
<li>A propos</li>
<li>Contact</li>
</ul>
</div>
Css:
#menu ul {
margin:0;
padding:0;
list-style-type:none;
text-align:center;
}
#menu li {
float:left;
margin:auto;
padding:0;
background-color:black;
display: inline;
vertical-align: middle;
}
#menu li a {
display:block;
width:100px;
color:white;
text-decoration:none;
}
#menu li a:hover {
color:#FFD700;
}
#menu ul li ul {
display:none;
}
#menu ul li:hover ul {
display:block;
}
#menu li:hover ul li {
float:none;
}
#menu li ul {
position:absolute;
}
#menu {
height:30px;
}
/* Logo */
#logo{
height: 190px;
width: 266px;
background-color:black;
}

Answer 1

#menu ul {
margin: 0;
padding: 0;
list-style-type: none;
text-align: center;
width: 700px;
/* some fixed width so, menu doesn't fall on next line*/
}
#menu li {
/* float: left; you can't align a floated element easily */
margin: auto;
padding: 0;
background-color: black;
display: inline-block;
vertical-align: middle;
}
#menu li a {
display: block;
width: 100px;
color: white;
text-decoration: none;
}
#menu li a:hover {
color: #FFD700;
}
#menu ul li ul {
display: none;
}
#menu ul li:hover ul {
display: block;
}
#menu li:hover ul li {
float: none;
}
#menu li ul {
position: absolute;
}
#menu {
height: 30px;
}
/* Logo */
#logo {
height: 190px;
width: 266px;
background-color: black;
}
<div id="menu">
<ul>
<li>Portfolio
<ul>
<li>Sous-item 1
</li>
<li>Sous-item 2
</li>
<li>Sous-item 3
</li>
</ul>
</li>
<li>Projets
</li>
<li id="logo"></li>
<li>A propos
</li>
<li>Contact
</li>
</ul>
</div>
If i got your question correct, then this is what you need to do. I have just made the required changes, rest of code is all yours.