How I can center a block vertically and horizontally with Bootstrap?

Question

I have this form:

<div class="container-fluid">
<div class="span5 well">
<h2>Authentification</h2>
<form method="POST">...</form>
</div>
</div>

How I can center that block (div span5 well) vertically and horizontally? Thank you.

Answer 1

Horizontal centering can be done by adding margin: 0 auto to an element that has no siblings.

Answer 2

<style>
.well
{       
    position:absolute;      
    width:200px;    
    height:200px;
    top: 50%;
    left: 50%;
    margin-top:-100px; /* negative number 1/2 height */
    margin-left:-100px; /* negative number 1/2 width */
    outline:1px solid #CCC;
}
</style>

<div class="container-fluid">
<div class="span5 well">
<h2>Authentification</h2>
<form method="POST">...</form>
</div>
</div>