How to add in title a date but with other color, like in iMDb titles?

add this code in functions.php file

add_filter( 'the_title', 'ta_modified_post_title');
function ta_modified_post_title ($title) {
    global $post;   
    $mynewdate = strtotime($post->post_date); 
    $title = $title.'<span class="modified">'.date('Y',$mynewdate).'</span>'.'-<span class="modified">'.date('d',$mynewdate).'</span>-'.'<span class="modified">'.date('m',$mynewdate).'</span>';
  return $title;
}

modify date by your own way.