input[type=range] {
    -webkit-appearance: none;
    margin: 20px 0;
    width: 100%;
}

    input[type=range]:focus {
        outline: none;
    }

    input[type=range]::-webkit-slider-runnable-track {
        width: 100%;
        height: 8px;
        cursor: pointer;
        animate: 0.2s;
        background: #0d6efd; /* How to reference to bootstrap? */ 
        border-radius: 25px;
    }

    input[type=range]::-webkit-slider-thumb {
        height: 20px;
        width: 20px;
        border-radius: 50%;
        background: #fff;
        box-shadow: 0 0 4px 0 rgba(0,0,0, 1);
        cursor: pointer;
        -webkit-appearance: none;
        margin-top: -6px;
    }

    input[type=range]:focus::-webkit-slider-runnable-track {
        background: #0d6efd; /* How to reference to bootstrap? */
    }

.range-wrap {
    width: 100%;
    position: relative;
    padding:0;
}

.range-value {
    position: absolute;
    top: -38%;
}

    .range-value span {
        width: 30px;
        height: 24px;
        line-height: 24px;
        text-align: center;
        background: #6c757d; /* How to reference to bootstrap? */
        color: #fff;
        font-size: 12px;
        display: block;
        position: absolute;
        left: 50%;
        transform: translate(-50%, 0);
        border-radius: 6px;
    }

        .range-value span:before {
            content: "";
            position: absolute;
            width: 0;
            height: 0;
            border-top: 10px solid #6c757d; /* How to reference to bootstrap? */
            border-left: 5px solid transparent;
            border-right: 5px solid transparent;
            top: 100%;
            left: 50%;
            margin-left: -5px;
            margin-top: -3px;
        }