Plugin breaks top-navigation-layout

Please link to a page on your site where I can see the issue.

Hello,

I cant link my site, because its closed to public.

But to show you this, I set up a new wordpress-page, installed theme Nirvana and “Indicate External Links”, and placed a “individual link” (https://cubecolour.co.uk) into the top-menu. Here is the site:
https://wp11011785.server-he.de/www/wp-newsletter-test/

It looks like this is due to the span being set as a block element in your theme’s stylesheet

#access a > span {
  display: block;
}

Try changing it to inline-block