body {
    background-color: black;
    color: white;
}

.white {
    color: white;
    padding: 15px;
    margin: 20px;
border: 1px solid red;
z-index: 10;
}

nav {position: absolute;}
.abc {position: sticky;
    top: 0;
z-index: 9;
}
h2 {z-index: 11;}