I added divs in the nav menu to make a structure where there’s a flexbox column for the links, that is suppose to grow when the other column containing the colors shrinks. Then there’s an IX on the menu button that makes the rainbow column vary in width when it’s clicked once, then on the second click to shrink the column.
Edit the IX I’ve done for the ranbow, it’s hooked on the open menu hamburger button. Add initial steps for each of the links with opacity zero, then add actions to make them appear one by one. If you’re not comfortable with those steps, make popcorn and go watch the videos about how to use Interactions 2.0 and learn how to add actions and limit their effects to the selected element (vs. to its class).