Hamburger menu not working

Problem/Motivation

While going through the theme and added the data and the menu links I found out that the hamburger menu is icon missing also hamburger menu is not working as well. Have attached the video recording for better understanding.

Steps to reproduce

Install the theme and add content and some menu links and switch to mobile or tablet screen.

Proposed resolution

There should be a hamburger menu icon also it should open up the menu on click.

Remaining tasks

none

User interface changes

yes

API changes

none

Data model changes

none