html, body, div {
    /* Height and width fallback for older browsers. */
    height: 100%;
    width: 100%;

    /* Set the height to match that of the viewport. */
    height: 100vh;

    /* Set the width to match that of the viewport. */
    width: 100vw;

    /* Remove any browser-default margins. */
    margin: 0;
}

#moldImg{
    position: absolute;
    top: 50%;
    left: 50%;
    width: 500px;
    height: 500px;
    margin-top: -250px; /* Half the height */
    margin-left: -250px; /* Half the width */
  }