Submenu size in navigation bar HTML CSS : I am trying to create a website, but i'm having a strange problem wiht my submenu in nav bar as you can see in this picture: 
[submenu problem][1]


  [1]: https://i.stack.imgur.com/LkMki.png

What i want is that my submenus elements have the same size, so i mean the same height. 

This is my html part:

    <header>
    			<div class="menu_bar">
    				<a href="#" class="bt-menu"><span class="icon-menu"></span>Menu</a>
    			</div>
    			
    			<div class="logo">
    				<img src="logo.png"> 
    			</div>
    			
    			<div class="box">
    				<form>
    					<input type="text" name="" placeholder="Type...">
    					<input type="submit" name="" value="Search">			
    				</form>
    			</div> 
    	 
    			<nav>
    				<ul>
    					<li><a href="#"><span class="icon-home"></span>Acceuil</a></li>
    					<li><a href="#"><span class="icon-briefcase"></span>Cities</a></li>
    					<li class="tete">
    						<a href="#"><span class="icon-rocket"></span>Activites<span class="flash icon-circle-down"</a>
    						<ul class="sousmenu">
    							<li><a href="#">Venice</a></li>
    							<li><a href="#">Rome</a></li>
    							<li><a href="#">Pisa</a></li> 
    						</ul>
    					</li>
    					<li><a href="#"><span class="icon-earth"></span>Services</a></li>
    					<li><a href="#"><span class="icon-envelop"></span>Contacter</a></li>
    				</ul>
    			</nav>
    		</header>


And this is CSS part for the submenu:

  

      header nav ul li:hover .sousmenu {
    	display:block;}
    
        header nav ul li .sousmenu {
    	display: none;
    	background:rgba(255, 0, 0, 0.2); 
    	margin-left: 0px; 
    	margin-top: 0px; 
    	position: absolute;
    	width: 150%;
    	z-index:1000;}
        
        header nav ul li .sousmenu li {
    	display:block;
    	overflow: hidden; 
    	border-bottom: 1px solid rgba(255,255,255,.5); }
     
    
        header nav ul li .sousmenu li a {
    	display: block;}

Can anyone help me plz? It's really urgent! Thanks! 

