how to make a line as a pseudo element?

So, I have stuck on this one. At the picture below you can see what should I do. However, I don't really understend how to make those crossed lines between the divs.

picture

Here is the code I have done so far: https://codepen.io/kaeses_developer/pen/wxyYdb

As I think, I have to create :before and :after pseudo element for .menu-item--large.

.menu-item--large {
flex-basis: 100%;
font-size: 36px;
background: none;
margin: 0 50%;
}

But how do I do it right? Or are there any different ways to make it?