h1 {
    text-align: center;
    background: aqua;
}

body {
    background-size: cover;
    background-image: url("http://cdn.pcwallart.com/images/ocean-sand-underwater-wallpaper-1.jpg");
    font-family: Georgia;
    font-size: 23;
}
   
.container {
    width: 990px;
    padding: 20px;
    border: 5px solid lightblue;
    background-color: white;
    margin-left: auto;
    margin-right: auto;
}

.marineB {
    margin-left: auto;
    margin-right: auto;
}

.nav ul  {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color:gray;
    font-family: Cursive; 
    font-size: 18px;
}

.nav li {
    float: left;
}

.nav li a{
    display: block;
    color: white ;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
    
}

.nav li a:hover {
    background-color: ;
    color:aqua;
}