I have a website with a background image but when I add a css navigation bar the hover tag doesn't work. the hover element works with out the back ground image but when i add the background image it dosent

here's my code

html

```
<!DOCTYPE html>
<html>
<head>
    <title>Cool</title>
    <link href="stylesheet.css" "type= "text/css" rel= "stylesheet">
    <link rel="icon" type="image/png" href="icon2.jpg"/>
</head>
<body>
    <div id="background-image">
    <div id="background-overlay">
    <h1>Cool</h1>
            <h2>Vertical Navigation Bar</h2>

            <ul>
            <li><a href="#home">Home</a></li>
            <li><a href="#news">News</a></li>
            <li><a href="#contact">Contact</a></li>
            <li><a href="#about">About</a></li>
            </ul>

            <p>hi</p>
    </div>
    </div>  
</body>
</html>

```

CSS

```
*{
z-index:-8;
}
body{
margin:0px;
}
#backround-image{
background-image:url("background.jpg");
background-size:cover;
background-position:center center;
position:relative;
top: 0;
bottom :0;
height: 100vh;
z-index: -10;
}
#backround-overlay{
position: absolute;
background-color: rgba(0,0,0,0.5);
top: 0;
bottom: 0;
height: 100%;
width: 100%;
z-index:-9;
}
h1{
text-align:center;
font-family:arial black;

}
l{
float:left;
}
ul {
list-style-type: none;
margin: 0;
padding: 0;
width: 200px;
background-color: #f1f1f1;
}

li a {
display: block;
color: #000;
padding: 8px 16px;
text-decoration: none;
}

/* Change the link color on hover */
li a:hover{
background-color: red;
color: black;
}

```

thanks for any help

Thomas