CSS help, responsive menu

I am trying to create my own responsive menu on a clients website, still busy styling it. The website is growbusiness.co.za

Its a responsive menu so to see the problem you need to resize your browser to 400px or less. If you open the mobile menu right at the top of the page by clicking the down arrow, you will see that the main “Menu” button covers some of the dropdown.

Is there anyone out there that can help me make it display like it should?
Thanks!