custom.css

input[type="range"]::-webkit-slider-runnable-track {
    background: linear-gradient(90deg, #4caf50, #81c784);
    border-radius: 10px;
    height: 6px;
}

input[type="range"]::-webkit-slider-thumb {
    background-color: #4caf50;
    border: 2px solid #388e3c;
    border-radius: 50%;
    width: 20px;
    height: 20px;
    cursor: pointer;
}

input[type="range"]::-moz-range-thumb {
    background-color: #4caf50;
    border: 2px solid #388e3c;
    border-radius: 50%;
    width: 20px;
    height: 20px;
    cursor: pointer;
}

input[type="range"]::-ms-thumb {
    background-color: #4caf50;
    border: 2px solid #388e3c;
    border-radius: 50%;
    width: 20px;
    height: 20px;
    cursor: pointer;
}