<div class="modal-body">
<form class="form-signin" action="index.php" method="post">
<input name="username" id="username" type="text" class="input-block-level" placeholder="Username">
<input name="password" type="password" id="password" class="input-block-level" placeholder="Password">
<button class="btn btn-medium btn-primary" type="submit" style="width:300">Login</button>
</form>