Question: This is very simple example of what I want to get. My question is about @returns tag. What should I write there? 

```js
class Base{
  /**
  * @returns {QUESTION: WHAT SHOUL BE HIRE??}
  */
  static method(){
    return new this()
  }
}

class Sub extends Base{
}

let base= Base.method() // IDE should understand that base is instance of Base
let sub= Sub.method() // IDE should understand that sub is instance of Sub

```

Answer: 
I did it for you with MU Grids and media queries, if you have questions, ask. I am always ready to help. This is codesandbox link. Let me know if it help you.
<https://codesandbox.io/s/charming-shirley-oq6l5>
Show my codesandbox answering your problem : <https://codesandbox.io/s/amazing-sound-1nj87>
It display your layout for **md lg xl** correctly. For **xs and sm** screens, sidenav & map take **full height** with a **break page between sidenav and appBa**r