basic_plus_slider.dart

SliderTheme(
      data: SliderTheme.of(context).copyWith(
        activeTrackColor: Colors.red[700],
        inactiveTrackColor: Colors.red[100],
        trackShape: RectangularSliderTrackShape(),
        trackHeight: 4.0,
        thumbColor: Colors.redAccent,
        thumbShape: RoundSliderThumbShape(enabledThumbRadius: 12.0),
        overlayColor: Colors.red.withAlpha(32),
        overlayShape: RoundSliderOverlayShape(overlayRadius: 28.0),
      ),
      child: Slider(
        value: _value,
        onChanged: (value) {
          setState(() {
            _value = value;
          });
        },
      ),
    ),