* {
  margin:0;
  padding:0;
}

.menu {
  overflow: hidden;
  display: inline-block;
}

.menu li {
  position:relative;
  float: left;
  list-style: none;
  margin-top: 51px;
}

.home_link {
  background-image: url("../images/menu/home_a.png");
  background-repeat: no-repeat; display:block;
  height:40px;
  width:41px; 
}
.home_link:hover { background-image: url("../images/menu/home_b.png"); }

.institucional_link  {
  background-image: url("../images/menu/institucional_a.png");
  background-repeat: no-repeat; display:block;
  height:40px;
  width:143px;
}
.institucional_link:hover { background-image: url("../images/menu/institucional_b.png"); }

.servicos_link  {
  background-image: url("../images/menu/servicos_a.png");
  background-repeat: no-repeat; display:block;
  height:40px;
  width:123px; 
}
.servicos_link:hover { background-image: url("../images/menu/servicos_b.png"); }

.clientes_link  {
  background-image: url("../images/menu/clientes_a.png");
  background-repeat: no-repeat; display:block;
  height:40px;
  width:120px; 
}
.clientes_link:hover { background-image: url("../images/menu/clientes_b.png"); }

.cases_link  {
  background-image: url("../images/menu/cases_a.png");
  background-repeat: no-repeat; display:block;
  height:40px;
  width:109px; 
}
.cases_link:hover { background-image: url("../images/menu/cases_b.png"); }

.contato_link  {
  background-image: url("../images/menu/contato_a.png");
  background-repeat: no-repeat; display:block;
  height:40px;
  width:119px; 
}
.contato_link:hover { background-image: url("../images/menu/contato_b.png"); }

.restrita_link  {
  background-image: url("../images/menu/restrita_a.png");
  background-repeat: no-repeat; display:block;
  height:40px;
  width:40px; 
}
.restrita_link:hover { background-image: url("../images/menu/restrita_b.png"); }