val owDarkBlue = Color(0x372E82)
val pwTextBlue = Color(0x476AF5)
val pwTextBrightColor = Color(0xB7B7C8)
.....	

private val DarkColorPalette = darkColors(
    primary = owDarkBlue,
    primaryVariant = pwTextBlue,
    onPrimary = Color.White,
    secondary = pwLightGreen,
    surface = owDarkBlue,
    onSurface = pwTextBrightColor
)

....

@Composable
fun MyTheme(
    darkTheme: Boolean = isSystemInDarkTheme(),
    content: @Composable() () -> Unit
) {
    val colors = if (darkTheme) DarkColorPalette else LightColorPalette
    MaterialTheme(
        colors = colors,
        typography = typography,
        shapes = shapes,
        content = content
    )
}

.....
@Preview
@Composable
fun DefaultPreview() {
    MyTheme {
        Scaffold(backgroundColor = MaterialTheme.colors.primary) {
            Surface(
                color = MaterialTheme.colors.surface,
                contentColor = MaterialTheme.colors.onSurface
            ) {
                Text("Hello Compose!")
            }
        }
    }
}