Header menu not displaying properly

I’m having trouble getting my menu to show up properly. Right now it shows up fine when its in mobile mode, but otherwise it displays as shown in the first picture below.

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Secondly the footer on some pages does not stretch fully across the page as seen in the second picture. How can I fix this issue?

Lastly, I would like the header to look like the header in the last picture below. How can I achieve this? Thanks for the help!

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The page I need help with: [log in to see the link]