/**
  * Gera um botão que dará submit a um formulário.
  * 
  * @return <string>
  */
 static function post_button($form_content, $url = null, $attrs = '')
 {
     $html = '<form action="' . url($url) . '" method="post" class="m-t" ' . $attrs . ' style="display: inline;">';
     $html .= $form_content;
     $html .= input_csfr();
     return $html .= '</form>';
 }
<div class="row">
    <!-- l:desktop m:tablet s:mobile -->
    <div class="col s0 l2 m1">
        &nbsp;
    </div>

    <div class="col s12 l8 m10">
        <form action="<?php 
echo url();
?>
" method="POST">
            <?php 
echo input_csfr();
?>

            <div class="row">
                <div class="col s12">
                    <?php 
echo element('page/back');
?>

                    <br/>

                    <h4>
                        <b class="grey-text text-darken-3">
                            Criar Conta
                        </b>
                    </h4>
                </div>
            </div>
 /**
  * 
  * @param type $options
  */
 static function open($action = null, $multipart = false)
 {
     $action = $action ? url($action) : url();
     return '<form action="' . $action . '" method="POST" enctype="multipart/form-data">' . input_csfr();
 }