range-firefox.css

.firefox {
    width: 160px;
    height: 20px;
}

.firefox input-thumb {
    width: 20px;
    height: 20px;
    border-radius: 100%;
    border: 2px solid white;
    background-color: #676774;
    box-shadow: 0px 1px 2px 0px rgba(0,0,0,0.55);
}

.firefox input-track {
    height: 30%;
    background-color: #E9E9ED;
    border-radius: 100px;
}

.firefox input-lower {
    border: 1px solid #0250BB;
    background-color: #0060DF;
    border-radius: 100px;
}

.firefox:hover input-lower,
.firefox:active input-lower {
    background-color: #0250BB;
    border-color: #054096;
}

.firefox input-upper {
    border: 1px solid #8F8F9D;
    border-radius: 100px;
}

.firefox:hover input-upper,
.firefox:active input-upper {
    border-color: #676774;
}

.firefox:hover input-track,
.firefox:active input-track {
    background-color: #D0D0D7;
}

.firefox:hover input-thumb {
    background-color: #484851;
}

.firefox:active input-thumb {
    background-color: #0060DF;
}

.firefox[disabled] input-track {
    background-color: #F4F4F6;
}

.firefox[disabled] input-lower {
    background-color: #C7C7CE;
    border-color: #C7C7CE;
}

.firefox[disabled] input-upper {
    border-color: #C7C7CE;
}

.firefox[disabled] input-thumb {
    background-color: #8F8F9D;
    box-shadow: none;
}