.dropzone {
    position: fixed;
    left: 0px;
    right: 0px;
    top: 0px;
    bottom: 0px;
    /* visibility: visible; */
    display: none;
    border: 0px dotted red;
    margin: 4px;
}

.dropzone.dragactive {
    background-color: #33FF0000;
    border: 3px dotted blue;
    /* visibility: visible; */
    display: block;
}