dragdrop.css

/*add this to avoid flickering*/
.plk-dd-inprogess > * {
    pointer-events: none;
}

/*dropzone style style*/
.plk-dd-dropzone {
    min-height: 50px;
}

/*drag drop styles*/

.plk-dd-spacing {
    height: 10px;
}

.plk-dd-spacing-dragged-over {
    padding: 25px;
}

.plk-dd-dragged-over {
    background-color: lightgray;
    opacity: 0.6;
    animation: blinker 1s linear infinite;
}

.plk-dd-dragged-over > div {
    background-color: lightgray;
    opacity: 0.6;
    animation: blinker 1s linear infinite;
}

.plk-dd-dragged-over-denied {
	background-color: red;
	opacity: 0.6;
	animation: blinker 1s linear infinite;
}

.plk-dd-in-transit {
    opacity: 0;
}

.plk-dd-in-transit > div {
     opacity: 0;
}

@keyframes blinker {
    50% {
        opacity: 0;
    }
}

.blink_me {
    animation: blinker 1s linear infinite;
}

/*for flex demo*/

.plk-flex .plk-dd-spacing {
    width: 20px;
    height: auto;
}

.plk-flex .plk-dd-dragged-over {
    background-color: lightgray;
    opacity: 0.6;
    animation: blinker 1s linear infinite;
}

.plk-flex .plk-dd-dragged-over > div {
    background-color: lightgray;
    opacity: 0.9;
    animation: blinker 1s linear infinite;
}

.plk-flex .plk-dd-in-transit {
    background-color: orangered;
}

.plk-flex .plk-dd-in-transit > div {
    background-color: orangered;
}

.plk-dd-noselect {
    -webkit-touch-callout: none; /* iOS Safari */
    -webkit-user-select: none; /* Safari */
    -khtml-user-select: none; /* Konqueror HTML */
    -moz-user-select: none; /* Old versions of Firefox */
    -ms-user-select: none; /* Internet Explorer/Edge */
    user-select: none; /* Non-prefixed version, currently
                                  supported by Chrome, Edge, Opera and Firefox */
}