jitsi-meet/css/components/_input-slider.scss

/**
 * Disable the default webkit styles for range inputs (sliders).
 */
input[type=range]{
    -webkit-appearance: none;
    background: none;
}

/**
 * Disable the default focus styles for webkit range inputs (sliders).
 */
input[type=range]:focus {
    outline: none;
}

/**
 * Include the mixin for a range input style.
 */
@include slider {
    background: $sliderTrackBackground;
    border: none;
    border-radius: 3px;
    cursor: pointer;
    height: 6px;
    width: 100%;
}

/**
 * Include the mixin for a range input thumb style.
 */
@include slider-thumb {
    -webkit-appearance: none;
    background: white;
    border: 1px solid $sliderThumbBackground;
    border-radius: 50%;
    box-shadow: 0px 0px 1px $sliderThumbBackground;
    cursor: pointer;
    height: 14px;
    margin-top: -4px;
    width: 14px;
}