I am trying to style sister div but not by using this id #rooms-booking-manager-change-search-form
Example
div + #rooms-booking-manager-change-search-form { padding:10px; font-size:18px; }
<div>Arrival Date: 19/09/2013</div>
<div>Departure Date: 21/09/2013</div>
<div>Nights: 2</div>
<form id="rooms-booking-manager-change-search-form"></form>
Solution:
div ~ #rooms-booking-manager-change-search-form {
background: red;
}