Mystile Header Horizontal Line

Hi,

I hope everything is going amazing with everybody.

I am currently using the Mystile theme. I have managed to center the navigation menu, and my logo, however, the Horizontal Line(double horizontal line) underneath the navigation menu is aligned towards the left.

I would like to have it aligned center. Hopefully, somebody can help me out with this. I have no experience using code; hopefully somebody can give me easy to understand instruction for this.

Hope to hear from anybody knowledgeable about this. Thanks in advance!

my wesbite is http://www.beachbrine.com