Un peu d'animation

page.css

.affiche {
  position: relative;
  height: 260px;
  overflow:hidden;
  padding: 0;
}

.affiche img {
    margin: 0;
    padding: 0;
    position: relative;
  }

page.html

<div class="affiche">
  <img id="pic" src="http://placehold.it/940x560" />
  <div class="container">
    <h1>Mon Super Site</h1>
    <p>ou on y cause de tout et de rien...</p>
  </div>
</div>

page.js

$(document).ready(function() {
    function up() {
        $("#plop").animate({"top": "-=200px"}, 1000, "linear", down);
    }
    
    function down() {    
        $("#plop").animate({"top": "+=200px"},1000, "linear", up);
    }

    up();
});