Thank you for your help!
After so many coffees and sleep deprivation I’m having a hard time making a easy “nav bar” with images.
the problem: There is a space on top of icons, why??? 
my css code:
<style>
* {
box-sizing: border-box;
}
body {
margin: 0;
padding: 0;
background-color: aqua
}
.navigation {
background-color: aliceblue;
position: fixed;
width: 100%;
height: 100px;
top: 0;
margin: 0;
padding: 0;
}
.navigation li {
list-style-type: none;
float: left;
top: 0;
margin: 0;
width: 100px;
border: 0;
}
</style>
</head>
<body>
<header class="navigation">
<nav>
<ul>
<li><a href="#">Link #1</a></li>
<li><a href="#">Link #2</a></li>
<li><a href="#">Link #3 </a></li>
<li><a href="#"><img src="images/home.jpg"></a></li>
<li><a href="#"><img src="images/home.jpg"></a></li>
<li><a href="#"><img src="images/home.jpg"></a></li>
</ul>
</nav>
