How to control the width of nested dropdowns in Foundation 6?

I'm using Foundation 6.4.3's Top Bar with Dropdown Menus. A first level of dropdowns displays tags, and for this the 200px width works well enough. Nested below tags, I've got entities that are sentence-like. They wrap, look awkward, & take up too much vertical space, but I haven't found a way to expand their width beyond 200px.

This question deals with reducing width – I wish that were my problem – but this question, unanswered is closer to what I'm looking for.

I'd just like to set a fixed width of 500-600px for second level dropdowns on medium and wider displays and appreciate your insights into how best to do that.