Centering div

HTML

<div class="headerContainer">
    <div id="header">
        <p>John Doe</p>
        <p>email</p>
    </div>
</div>

CSS

body {
    background-color: #f0f0f0;
}
div {
    border-radius: 5px;
}
#header {
    /* position: fixed; */
    background-color: #3399ff;
    color: white;
    width: 60%;
    margin: auto;
}
#header p {
    display: inline;
}