cardTheme color with opacity make confirm password color still light

[yogithesymbian]

cardTheme: CardTheme(
                  color: kColorYellow.withOpacity(0.7),
                  elevation: 10.0,
                  margin: EdgeInsets.only(top: 30.0),
                  shape: ContinuousRectangleBorder(
                    borderRadius: BorderRadius.circular(90.0),
                  ),
                ),