Dropdown Select does not conform MUI Theme, especially in dark mode

[wongyiuhang]

Third-party library react-select is used, when a dropdown question has more than 10 options. However, when dark mode is enabled, the option text changed to white, while the option background maintains to be white.

I suggest to pass MUI theme palette to the style props of react-select. I will create a PR asap.

material-survey/src/components/DropdownQuestion/Dropdown.js

Lines 51 to 61 in d3b1a38

	styles={{
	menu: provided => ({
	...provided,
	fontFamily: "Roboto, sans-serif"
	}),
	menuPortal: provided => ({ ...provided, zIndex: 10000 }),
	container: provided => ({
	...provided,
	fontFamily: "Roboto, sans-serif"
	})
	}}