Max Mega Menu in two lines strech

Hello! I have created a max mega menu with many items (12). I like the idea of two lines, but the problem is that I have 8 on the top and only 3 on the bottom. Is there any way to stretch the menu, so that the items are equal 6 and 6? Something similar to this page: https://www.ggmgastro.com/es-es-eur
Or should I create 2 menus, one below the other?
Thank you!

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