SO input-block-level
class="input-block-level" for form inputs. see http://is.gd/5gFrME
by panchroma
HTML
<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.2.2/css/bootstrap-combined.min.css">
<script src="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.2.2/js/bootstrap.min.js"></script>
<div class="container">
<div class="row">
<div class="span4 formWrapper">
<h3>Newsletter</h3>
<input type="text" name="name" placeholder="Name" class="input-block-level" />
<input type="text" name="surname" placeholder="Surname" class="input-block-level" />
<input type="text" name="email" class="input-block-level" placeholder="Email" />
<button type="submit" class="btn btn-inverse pull-right"><i class="icon-envelope icon-white"></i>Subscribe</button>
</div>
</div> <!-- end row -->
</div><!-- end container -->
CSS
.formWrapper {
-moz-box-sizing: border-box;
-webkit-box-sizing: border-box;
box-sizing: border-box;
padding: 0px;
border: 1px solid #ccc;
background-color: white;
}
.formWrapper input{
width:100%;
}