Hero image sits under navigation

[ryancreatescopy]

Describe the bug

On the homepage, the navigation bar should be above the hero image, not sitting on top of it. At the moment, the nav bar sits on top of the image meaning the focus of the image feels squashed towards the top. This isn't a major bug because it doesn't cut off any of the image, but if we were to swap images in the future to something with detail at the top of the image it runs the risk of being cut off.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'ethereum.org'

Expected behavior

The nav bar should be above the image in hierarchy and not just sit on top of it.

Screenshots