Toggle Menu not showing up on small screens

[Hannili]

Description

Collapse sidebar / Toggle menu not showing up on small screens.

Environment

Cannot be seen anymore on the projects own website:
https://mmistakes.github.io/minimal-mistakes/docs/quick-start-guide/

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Expected behavior

A toggle menu button should appear on small screens (instead of showing the whole menu). It was introduced and discussed here: #607

I also have seen this feature on the projects documentation website a while ago.
Was it intendedly removed?

Steps to reproduce the behavior

Use the mobile view of your browser on https://mmistakes.github.io/minimal-mistakes/docs/quick-start-guide/

[mmistakes]

Looks like Prettier mangled some of the Sass used to make the toggle work. I've corrected that and it should be fixed on master.