[Flutter] Custom a Slider with SliderTheme

                    SliderTheme(
                      data: SliderTheme.of(context).copyWith(
                        activeTrackColor: Colors.white,
                        inactiveTrackColor: Color(0xFF8D8E98),
                        overlayColor: Color(0x29EB1555),
                        thumbColor: Color(0xFFEB1555),
                        thumbShape: RoundSliderThumbShape(
                          enabledThumbRadius: 15.0,
                        ),
                        overlayShape: RoundSliderOverlayShape(
                          overlayRadius: 30.0,
                        ),
                      ), // provide a default theme
                      child: Slider(
                        value: height.toDouble(),
                        min: ,
                        max: ,
                        onChanged: (double newVal) {
                          setState(() {
                            height = newVal.round();
                          });
                        },
                      ),
                    ),

Docs