.stuck {
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 2000;
    border-top: 0;

    -webkit-box-shadow: 0 0 5px rgba(0,0,0,0.45);
    -moz-box-shadow: 0 0 5px rgba(0,0,0,0.45);
    box-shadow: 0 0 5px rgba(0,0,0,0.45);
}

.stuck + div,
.stuck + section {
    margin-top: 80px;
}