style.css

[data-simple-slide]{
    overflow: hidden;
    padding: 0;
    list-style: none;
    width: 500px;
    height: 500px;
    position: relative;
}

[data-simple-slide] > li{
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center center;
    overflow: hidden;
}

/* [data-simple-slide].transition > li{
    display: block;
    opacity: 1;
    transition: opacity 0.5s;
} */

.slidecontainer {
    width: 100%; /* Width of the outside container */
}

/* The slider itself */
.slider {
    -webkit-appearance: none;  /* Override default CSS styles */
    appearance: none;
    width: 100%; /* Full-width */
    height: 25px; /* Specified height */
    background: #d3d3d3; /* Grey background */
    outline: none; /* Remove outline */
    opacity: 0.7; /* Set transparency (for mouse-over effects on hover) */
    -webkit-transition: .2s; /* 0.2 seconds transition on hover */
    transition: opacity .2s;
}

/* Mouse-over effects */
.slider:hover {
    opacity: 1; /* Fully shown on mouse-over */
}

/* The slider handle (use -webkit- (Chrome, Opera, Safari, Edge) and -moz- (Firefox) to override default look) */ 
.slider::-webkit-slider-thumb {
    -webkit-appearance: none; /* Override default look */
    appearance: none;
    width: 25px; /* Set a specific slider handle width */
    height: 25px; /* Slider handle height */
    background: #4CAF50; /* Green background */
    cursor: pointer; /* Cursor on hover */
}

.slider::-moz-range-thumb {
    width: 25px; /* Set a specific slider handle width */
    height: 25px; /* Slider handle height */
    background: #4CAF50; /* Green background */
    cursor: pointer; /* Cursor on hover */
}