superset/assets/visualizations/PlaySlider.css

.play-slider {
    height: 100px; 
    margin-top: -5px;
}

.slider-selection {
    background: #efefef;
}

.slider-handle {
    background: #b3b3b3;
}

.slider.slider-horizontal {
    width: 100% !important;
}

.slider-button {
    color: #b3b3b3;
    margin-right: 5px;
}