[TechDocs] Docs side menu not collapsing in small devices

Backstage is using mkdocs material theme, in material if you open the page in small devices then side menu will become collapsable but it is not happening in backstage site.

Expected Behavior

Techdocs content side menu should collapse. you can try open this site and switch to mobile view. https://squidfunk.github.io/mkdocs-material/setup/setting-up-navigation/

Current Behavior

Backstage site - techdocs content side menu takes all the space and not readable in mobile device. Screenshot from backstage official demo site. https://demo.backstage.io/docs/default/component/backstage/features/software-catalog/

Steps to Reproduce

Open backstage demo site in mobile view. docs side menu doesnt become collapsable as like mkdocs material theme. https://demo.backstage.io/docs/default/component/backstage/features/software-catalog/

To test I installed mkdocs on my local pip3 install mkdocs-techdocs-core==0.2.1

and did mkdocs build and serve the site. It is behaving as expected but when the same site docs were served with backstage then the side menu stopped collapsing for small screens.

Backstage backend deps:

  "dependencies": {
    "@backstage/backend-common": "^0.9.13",
    "@backstage/catalog-client": "^0.5.2",
    "@backstage/catalog-model": "^0.9.7",
    "@backstage/config": "^0.1.11",
    "@backstage/core-plugin-api": "^0.2.1",
    "@backstage/integration": "^0.5.0",
    "@backstage/plugin-auth-backend": "^0.4.9",
    "@backstage/plugin-catalog-backend": "^0.18.0",
    "@backstage/plugin-techdocs-backend": "^0.10.9",
    "@gitbeaker/node": "^29.2.0",
    "@octokit/rest": "^18.5.3",
    "dockerode": "^3.2.1",

  },
  "devDependencies": {
    "@backstage/cli": "^0.6.14",
  },

• NodeJS Version (v14):
• Operating System and Version (e.g. Ubuntu 14.04):
• Browser Information:

[erikxiv]

An attempt to collapse the sidebar on small devices: https://github.com/backstage/backstage/pull/9493

[erikxiv]

I think this can be considered fixed with #9493