main.dart

 child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                Image.asset("assets/images/main-img.png"),
                RichText(
                    textAlign: TextAlign.center,
                    text: TextSpan(children: <TextSpan>[
                      TextSpan(
                          text: Constants.textIntro,
                          style: TextStyle(
                            color: Constants.kBlackColor,
                            fontWeight: FontWeight.bold,
                            fontSize: 30.0,
                          )),
                      TextSpan(
                          text: Constants.textIntroDesc1,
                          style: TextStyle(
                              color: Constants.kDarkBlueColor,
                              fontWeight: FontWeight.bold,
                              fontSize: 30.0)),
                      TextSpan(
                          text: Constants.textIntroDesc2,
                          style: TextStyle(
                              color: Constants.kBlackColor,
                              fontWeight: FontWeight.bold,
                              fontSize: 30.0)),
                    ])),
                SizedBox(height: size.height * 0.01),
                Text(
                  Constants.textSmallSignUp,
                  style: TextStyle(color: Constants.kDarkGreyColor),
                ),
                SizedBox(height: size.height * 0.1),
                SizedBox(
                  width: size.width * 0.8,
                  child: OutlinedButton(
                    onPressed: () {
                      result == null
                          ? Navigator.pushNamed(
                              context, Constants.signInNavigate)
                          : Navigator.pushReplacementNamed(
                              context, Constants.homeNavigate);
                    },
                    child: Text(Constants.textStart),
                    style: ButtonStyle(
                        foregroundColor: MaterialStateProperty.all<Color>(
                            Constants.kPrimaryColor),
                        backgroundColor: MaterialStateProperty.all<Color>(
                            Constants.kBlackColor),
                        side: MaterialStateProperty.all<BorderSide>(
                            BorderSide.none)),
                  ),
                ),
                SizedBox(
                  width: size.width * 0.8,
                  child: OutlinedButton(
                    onPressed: () {},
                    child: Text(
                      Constants.textSignIn,
                      style: TextStyle(color: Constants.kBlackColor),
                    ),
                    style: ButtonStyle(
                        backgroundColor: MaterialStateProperty.all<Color>(
                            Constants.kGreyColor),
                        side: MaterialStateProperty.all<BorderSide>(
                            BorderSide.none)),
                  ),
                )
              ],
            ),