vertical align NAV into HEADER - html

Question

I have a fixed header with a <nav> into it. The problem is that I tried a lot of things, but my elements don't vertically align on middle. I cannot use line-height because it depends on screen resolution.
CSS
header {
width: 100%;
height: 15%;
background-color: rgba(30, 30, 30, 0.75);
color: white;
font-family: 'Roboto', sans-serif;
font-weight: bold;
text-align: center;
position: fixed;
text-transform: uppercase;
overflow: hidden;
}
header nav {
text-align: center;
display: inline-block;
position: absolute;
top: 0;
bottom: 0;
right: 0;
left: 0;
margin: 0;
}
header nav a {
/*line-height: 6;*/
color: white;
padding: 14px 16px;
text-align: center;
display: inline;
text-decoration: none;
-webkit-transition: all 0.3s;
-moz-transition: all 0.3s;
-ms-transition: all 0.3s;
-o-transition: all 0.3s;
transition: all 0.3s;
}
HTML
<header>
<div>
<nav>
<a class="active" href="">Home</a>
News
Info
Contact
</nav>
</div>
</header>
Demo: http://jsfiddle.net/JJ8Jc/4082/

Answer 1

You can use display flex method to align elements vertically and/or horizontally
I just added
header nav {
display:flex;
justify-content: center;
align-items: center;
}
so you example now become:
header {
width: 100%;
height: 15%;
background-color: rgba(30, 30, 30, 0.75);
color: white;
font-family: 'Roboto', sans-serif;
font-weight: bold;
text-align: center;
position: fixed;
text-transform: uppercase;
overflow: hidden;
display:flex;
}
header nav {
text-align: center;
display:flex;
position: absolute;
top: 0;
bottom: 0;
right: 0;
left: 0;
margin: 0;
justify-content: center;
align-items: center;
}
header nav a {
/*line-height: 6;*/
color: white;
padding: 14px 16px;
text-align: center;
display: inline;
text-decoration: none;
-webkit-transition: all 0.3s;
-moz-transition: all 0.3s;
-ms-transition: all 0.3s;
-o-transition: all 0.3s;
transition: all 0.3s;
}
<header>
<div>
<nav>
<a class="active" href="">Home</a>
News
Info
Contact
</nav>
</div>
</header>

Answer 2

on your .nav css, change top: 0; for top: 50%; then add these lines:
-webkit-transform: translateY(-50%);
-ms-transform: translateY(-50%);
transform: translateY(-50%);
and remove bottom: 0;
jsfiddle
Alternatively, you could use padding-bottom and padding-top to increase the header size keeping the content on the middle. Or, yet, let it flex like the other answer has already suggested.
header {
width: 100%;
height: 15%;
background-color: rgba(30, 30, 30, 0.75);
color: white;
font-family: 'Roboto', sans-serif;
font-weight: bold;
text-align: center;
position: fixed;
text-transform: uppercase;
overflow: hidden;
}
header nav {
text-align: center;
display: inline-block;
position: absolute;
top: 50%;
-webkit-transform: translateY(-50%);
-ms-transform: translateY(-50%);
transform: translateY(-50%);
right: 0;
left: 0;
margin: 0;
}
header nav a {
/*line-height: 6;*/
color: white;
padding: 14px 16px;
text-align: center;
display: inline;
text-decoration: none;
-webkit-transition: all 0.3s;
-moz-transition: all 0.3s;
-ms-transition: all 0.3s;
-o-transition: all 0.3s;
transition: all 0.3s;
}
<header>
<div>
<nav>
<a class="active" href="">Home</a>
News
Info
Contact
</nav>
</div>
</header>