Rhye theme: smooth element appearance in overlay menu

/* Say your logo is inserted with #overlay-menu-logo ID like this:
   <img id="overlay-menu-logo" src="#" alt="">
*/

#overlay-menu-logo {
  transition: opacity 0.3s ease;
}

.header.opened #overlay-menu-logo {
  opacity: 1;
}

.header #overlay-menu-logo {
  opacity: 0;
}