Bookie - Add background color overlay in slider

style.css

.toko-slider-wrap .toko-slides .toko-slide {
	z-index: 1;
    position: relative;
}
.toko-slider-wrap .toko-slides .toko-slide:before {
    background-color: red;
    opacity: 0.3;
	position: absolute;
    width: 100%;
    height: 100%;
    content: "";
    z-index: -1;
}