Twitter bootstrap responsove input width incorrect

Question

recently i started to create my first responsive design with twitter bootstrap.

My problem is i tried a few things still not working, if i wrapp my from around with a class of span, the input widths are incorrect

code

<div class="container">
    <div class="row-fluid">

    <form class="span4" method="POST" action="http://localhost/mjb/index.php/" accept-charset="UTF-8">
        <label for="username">Username</label>      <input class="span4" type="text" name="username" value="" id="username">
        <label for="password">Password</label>      <input class="span4" type="password" name="password" id="password">
        <button class="btn btn-block btn-success">Login</button>
    </form>
</div>
</div>

Could someone please point out what im doing wrong?

Answer 1

Solved.

Needed to add class="input-block-level" to the input field