If you would like to see the code in action, I have a Code Sandbox that is using my API keys.
The keys for the api are only activated for the specified Code Sandbox link. They have been heavily restricted. You must substitute YOUR_OWN_KEY_HERE with your own Google Maps API key. If you see an error message displayed in the blue box, your keys are not working properly.
This is a simple navigation bar that loads a list of cities, and has a floating indicator bar to show the current selection. On resize of window, it recalculates the position to continue to show the current selection. When a city is selected, it will show the current time in that location!