    public record MyTheme : LumexTheme
    {
        public MyTheme()
        {
            DefaultTheme = ThemeType.Light;

            Light = new ThemeConfigLight()
            {
                Layout = new LayoutConfig() { /* ... */ },
                Colors = new ThemeColorsLight() { /* ... */ },
            };

            Dark = new ThemeConfigDark()
            {
                Layout = new LayoutConfig() { /* ... */ },
                Colors = new ThemeColorsDark() { /* ... */ },
            };
        }
    }