inline css screwing things up for JqueryMegaMenu

Hi everybody, new here so bear with me on this…

I am building a site as a favour to a friend who is launching a little record label. I recommended wordpress for the flexability and great c.m.s. and all was going well using the builder foundation blank theme, until I tried to add the JqueryMegaMenu (which seems like the perfect solution for what we want) as a widget.

For some reason some inline css is causing the widget bar to have a hidden overflow property, which hides the dropdown. See the site here. (the megamenu is the second one)
I have tried to add an overriding style into my css using the !important property but it doesn’t work, and from what I can gather from what i’ve read in replies to similar problems, it looks like the solution could be some adding some jquery code to override the css.
The only problem is i’m no coder, and I’ve no idea how I might go about this.

If anyone could have a look at the site and maybe give me a few pointers, I’d be eternally grateful! This problem is starting to give me a headache, and I’d really love to get this menu working.