input-range.css

input-range {
    /* Mandatory */
    display: inline-flex;
    align-items: center;
    justify-content: center;
    position: relative;
    box-sizing: border-box;
    user-select: none;
    padding: 0;
    margin: 0;

    /* Mandatory - custom */
    width: 128px;  
    height: 12px;
}

input-range * {
    /* Mandatory */
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

input-track {
    /* Mandatory */
    display: flex;
    width: 100%;
    overflow: hidden;

    /* Mandatory - custom*/
    height: 100%;

    /* custom */
    background-color: #D4D4D4;
}

input-lower {
    /* Mandatory */
    display: block;
    height: 100%;
    width: 50%; /* JS action */

    /* custom - here */
}


input-upper {
    /* Mandatory */
    display: block;
    height: 100%;
    flex-grow: 1;

    /* custom - here */
}

input-thumb {
    /* Mandatory */
    display: block;
    position: absolute;
    touch-action: none;

    /* Mandatory */
    top: 50%;
    left: 0; /* IE11 */
    transform: translate(-50%, -50%);

    /* Mandatory - custom */
    height: 100%;
    width: 12px;

    /* custom */
    background-color: black;
}

input-range[disabled] {
    /* Mandatory */
    pointer-events: none;
}

input-range[disabled] input-track {
    /* custom */
    background-color: #E5E5E5;
}

input-range[disabled] input-thumb{
    /* custom */
    background-color: #C2C2C2;
}