Jquery delay

Jquery delay


i want to apply a style to div with a class="project-hover" for a delay of 3 secondes, then remove the style :
i use this syntax, but it seems incorrect, plz help: 




/************************** HTML Code ************************************/
<li class="project-hover activer">
<a href="#"  class="show-actualite"><img src="./images/actualites.jpg" alt=""></a>
      <div class="details">
        <p>Nostrud nostrud quidne pneum imputo, capio quis. </p>