But when I try to animate the menu items out again, when clicking the burger to close the menu, the items are still visible when they move back into place. Looks as stupid as I am.
I don't get what I could do to about it, except for an transition of 0s for the items. But thats not cool.
You may add width:0;to the @media all and (max-width: 1000px).
Also ( and this is not a must) you may move some rules from the .is-open to the @media all and (max-width: 1000px).
I’ve made a fork: https://codepen.io/giaco/pen/ELmYbv?editors=0100
I hope this helps.