I'm having a design issue with my css vertical menu.

It's working but it does not have the effect i would like to have when I do a mouse hover on a category

Below, you will see a simple vertical menu which appears when you hover your mouse over the main category

However I would like to have a small effect :
When the mouse is hover a category, i would like to add a background color (black).

It's working but I would like that the height and the width of the background to stick exactly to the same height and width of the text. Currently, I dont know why; the height of the background is more than the height of my text.
Here is some pictures of how it's right now and how i would like to be be.

How it 's now:
![How it i snow](https://i.stack.imgur.com/11sCH.png)

How I would like it to be:
![How I would like it to be](https://i.stack.imgur.com/JmVJW.png)

Here is my code Html code

```
<div id="menu">
                    <ul id="MenuDeroulant">
                        <li style="margin-left:-10px;"><a href="#" style="">Main categorie</a>
                            <ul>            
                                <li><a href="" >Subcat 1</a></li>
                                <li><a href="" >Subcat 2</a></li>

                            </ul>
                        </li>
                    </ul>

```

Here is my css code:

```
    #MenuDeroulant
{
    margin: 0;
    padding: 0
}
#MenuDeroulant li
{    
    float: left;
    list-style: none;
}
#MenuDeroulant li a
{    
    display: block;
    padding: 0px 0px;
    text-decoration: none;
    color: #000; 
    white-space: nowrap;
    text-align:center;
}

#MenuDeroulant li a:hover
{    
    background: #000;
    color: #FFF;
} 

#MenuDeroulant li ul
{   visibility: hidden;
    padding: 0px 0px;
}

#MenuDeroulant li ul li
{    
    float: none;
    display: inline;
}

#MenuDeroulant li ul li a
{    
width: auto;
padding: 0px 0px;
} 

#MenuDeroulant li ul li a:hover
{    
background: #0000;
padding: 0px 0px;
} 

```

Thanks in advance for your help and I wish you a very nice day,

Anselme