HTML css of sorts

<!DOCTYPE html>
<html>
<head>
<style>
body {
    margin-left: 200px;
    background: #5d9ab2 url("http://i.imgur.com/tDWZK5p.png") no-repeat top left;
}

.center_div {
    border: 5px solid gray;
    margin-left: auto;
    margin-right: auto;
    width: 90%;
    background-color: #d0f0f6;
    text-align: left;
    padding: 8px;
}
</style>
</head>
<body>

<div class="center_div">
  <h1>Hello World!</h1>
  <p>In this example, note that the tree image itself does not have a background overlay</p>
</div>

</body>
</html>