Add a shadow below the sticky bar at the top of the directory

[michellengaiCDS]

There should be a slight shadow below the top sticky bar: https://zpl.io/2yznvep

[SupeDeDupe]

Because of how the sticky header is inside the paper element, the header does not span across the entire horizontal of the paper component. To add the shadow style to the bottom of the sticky header, the component will have to be moved such that it spans the entire horizontal of the paper component. Some form of event listener or code/css with similar functionality will also have to be implemented so the shadow only appears during the scroll, and not when the element is fixed between the "Find benefits and services" header and the quick links box.

For applying the shadow on the bottom, but this leaves the event listener problem open:
https://stackoverflow.com/questions/3971880/how-to-make-shadow-on-border-bottom