body, html {
    height: 100%;
    margin: 0;
}

.parallax {
    /* The image used */
    background-image: url('https://engineering.purdue.edu/ChE/research/sustainability/controls/images/midbanner.png');

    /* Set a specific height */
    min-height: 300px;

    /* Create the parallax effect */
    background-attachment: fixed;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
}

.story-content {
    position: relative;
    z-index: 1;
}

.parallax::before {
    content: "";
    display: block;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background:
    z-index: 0;
}