Positioning of Nav Bar | WordPress.org

I am using the Evolve theme on my http://www.stokerssiding.com.au site. I would like to position the nav bar below the header. Currently the nav bar displays halfway down the header and corrupts the formatting of the header. Could you suggest some CSS code that would reposition the nav bar below the header. Thanks. I posted this query to WordPress support around 1 week ago, haven’t had a response yet.

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