Center an auto-width div?

for parent block or body – text-align:center;
for centerd block- display:inline-block;

.center {
    display: inline-block;
    background: red;
}

body {
    text-align: center;
}
    
<div class="center">
    <p contenteditable="true"> write text </p>
</div>

DEMO http://jsfiddle.net/RXP4F/

Content Editable MDN