Text align: center on list item block - html

Question

I've created simple responsive navigation menu with media queries. I faced the weird situation. After applying text-align:center to center text in blocks, the first li element is moved slightly to left, others are centered fine. I can't figure out what's the issue. I tried margin: 0 auto, it doesn't work for me.
This is what's happening:
Here's the code:
<header>
<div class="logo">Logo</div>
<div class="menu" role="button">
<span></span>
<span></span>
<span></span>
</div>
<nav class="navigation">
<ul>
<li>home</li>
<li>blog</li>
<li>team</li>
<li>contact</li>
</ul>
</nav>
</header>
CSS:
header{
background:grey;
.logo{
font-size:40px;
color:white;
background:blue;
width:200px;
display:inline-block;
}
.menu{
display:inline-block;
float:right;
}
nav{
display:inline-block;
ul{
margin:0;
padding:0;
li{
display:inline-block;
margin: 0 20px;
background:orange;
}
}
}
}
#media screen and(max-width:600px){
header{
.menu{
display:inline-block;
height: 40px;
width: 40px;
margin:10px;
span{
border-top: 5px solid #fff;
display: block;
margin: 5px 0;
}
}
.navigation{
display:block;
ul{
margin:0;
padding:0;
text-align: center;
li{
width:100%;
display:block;
background:orange;
margin:0;
}
}
}
}
}