<!DOCTYPE html>
<html>
<head>
<title>Test</title>
<style>
.parent { 100%;
margin:0 auto;
text-align:center;
background-color:#ccc;
}
.children {
height: 45px;
60px;
margin: 5px;
text-align: center;
line-height: 45px;
border: 1px solid #006fc2;
color: #006fc2;
border-radius: 5px;
display:inline-block;
}
</style>
</head>
<body>
<div class="parent">
<div class="children">100</div>
<div class="children">200</div>
<div class="children">500</div>
<div class="children">1000</div>
</div>
</body>
</html>