body {
    background-color:olive;
    height: 100vh;
    width: 100vw;
    overflow: hidden;
}

img {
    height: 200px;
}

img[id^="img-"] { /*^= means “starts with”*/
    position: absolute;
    left: 50%;  /* x relative to parent */
    top: 50%;   /* y relative to parent */
    transition: 0.5s;
}

div[id^="randombox-"] { /*^= means “starts with”*/
    position: absolute;
    left: 50%;  /* x relative to parent */
    top: 50%;   /* y relative to parent */
    transition: 0.5s;
}

#printHeader {
    display: none;
}