Hamburger Menu is Missing

I’ve tried the previous recommendations from other threads, and it’s not there on the site I’m working on.
vividhairandbeauty.com.au

Hello there,

Your mobile menu toggle actually presents in there. However white menu bar makes it invisible as it’s white as well. You can use this simple CSS code to make it darker.

    .btn-menu {
      color: #000;
    }

Add it to Appearance > Customize > Additional CSS from dashboard.

Regards,
Kharis