Martyer

wrapper {
  display: block;
  width: 1000px;
  margin: 0 auto;
  padding: 0;
  overflow: hidden;
  background-color: white;
}

#main-navigation li:last-of-type a {
    border-right: none;
}

.no-select {
  -webkit-user-select: none;
  -moz-user-select: none;
  user-select: none;
}

[].forEach.call(document.querySelectorAll(".no-context"), function(element) {
  element.addEventListener("contextmenu", function(event) {
    event.preventDefault();
  });
});

wrapper {
    height: 100%;
}

wrapper:after {
    display: block;
    content: '';
    clear: both;
}

wrapper {
	display: block;
}

.jcarousel-skin-tango .jcarousel-item {  height: 75px;  width: 75px;}

<ul style="margin: 0px; overflow: hidden; position: relative; top: 0px; padding: 0px; left: 0px; width: 525px;" class="jcarousel-list jcarousel-list-horizontal" id="mycarousel">

<header>
<div></div>
<div></div>
<div></div>
</header>

header {
width: 75%;
margin: 0 auto;
}
div {
float: left;
width: 33%;
}
header::after {
content: "";
display: block;
clear: both;
}