How to add gray layer to google map?

Question

css

How can I add a gray color over the map, well, or how to make the map black and white. And I would like to be able to click on the map at the same time :)
https://codepen.io/anon/pen/QMKPEz

Answer 1

https://mapstyle.withgoogle.com/

Answer 2

https://snazzymaps.com/