We're currently developing a theme, so here's a preview link: https://92cggj8qpcxttzv0-3935153.shopifypreview.com
I've done the solution as indicated here (for the main navigation items): http://www.expertshopify.com/shopify-code-snippets/shopify-venture-theme-activate-megamenu-when-mous...
Still got a small problem, though: I want the subcategories to also appear on hover. Did anyone find a solution for this?
Would appreciate the help.