d.clixer on "[Plugin: Contact Form 7] How can I add custom atts to contact form shortcode"

How can I add custom atts to contact form shortcode

[contact-form-7 id="108" title="Contact form 1" bg_color="red"]

       // custom background
       add_filter( 'wpcf7_form_elements','mycustom_wpcf7_form_elements');

       function mycustom_wpcf7_form_elements( $form ) {
          extract(shortcode_atts(array(
                'id' => '',
                'title' => '',
		'bg_color' => ''
   	  ), $atts));
          echo "<style> #{$id} { background : $bg_color } </style>";

	  $form = do_shortcode( $form );
	  return $form;
       }

how should I do
if there is more than one form in one page

thanks before..

http://wordpress.org/plugins/contact-form-7/