fix: navigation sidebar scrolling on mobile devices

[Agrendalath]

Fixes #1935.

This fixes the following issues with the navigation sidebar on mobile devices:

1. The sidebar on mobile devices was automatically closed when scrolling down due to the browser's resize event when hiding the URL bar.
2. The sidebar was not displayed as full-screen because the position from Bootstrap's fixed-top utility class was overridden by the position: relative rule for the .outline-sidebar-wrapper selector.
3. The full-screen sidebar could not be scrolled due to the lack of vertical overflow.

Testing instructions

Check the use cases described above with the narrow viewport.

Deadline

"None"

Other information

Private-ref: BB-7413

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.49%. Comparing base (c694ac6) to head (56ba046).
⚠️ Report is 9 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1927   +/-   ##
=======================================
  Coverage   91.48%   91.49%           
=======================================
  Files         353      353           
  Lines        5838     5843    +5     
  Branches     1356     1357    +1     
=======================================
+ Hits         5341     5346    +5     
  Misses        478      478           
  Partials       19       19           

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[itsjeyd]

Hey @Agrendalath, this looks like a clear-scope bug fix. Could you check the instructions for that contribution path and complete the remaining steps (right now that would just be #1 and #3).

[Agrendalath]

@itsjeyd, done.

[Agrendalath]

@itsjeyd, can I move it to the engineering review myself, or should I ping you to double-check first?

[itsjeyd]

@Agrendalath You're welcome to update the status yourself :) However, having cleared product review this would go to Ready for Review now, and only move to In Eng Review once an upstream reviewer has been confirmed and they've started reviewing.

[itsjeyd]

@openedx/committers-frontend-app-learning This is ready for you.

[brian-smith-tcril]

Thanks for the PR!

It looks like this has some conflicts now (likely because #1923 landed). If you could rebase this that would be perfect!

I also left a comment with a small question.

[farhaanbukhsh]

The code changes look good to me and I have tested them as well. Can we add some tests here @Agrendalath ?

[Agrendalath]

@brian-smith-tcril, @farhaanbukhsh, I replaced the SCSS override with the Paragon class and added tests.

[farhaanbukhsh]

👍

✅ I tested this: on the master devstack

• The sidebar closing issue is resolved
• The sidebar takes the whole screen

✅ I read through the code
✅ I checked for accessibility issues
❌ Includes documentation

[farhaanbukhsh]

@brian-smith-tcril do you want to review this PR again?

[brian-smith-tcril]

Could this be simplified by using matchMedia?

[Agrendalath]

@brian-smith-tcril, I like this idea. However, I'm not sure about all the consequences. E.g., it would likely change existing behavior (e.g., when rotating the phone) beyond what we can consider a bug fix. A follow-up refactor would be more suitable for such a change.

[brian-smith-tcril]

One other thing I haven't tested but want to look into is if this changes the behavior on mobile when rotating the device (both switching from landscape to portrait and from portrait to landscape).

[farhaanbukhsh]

@brian-smith-tcril @Agrendalath I tried changing the orientation on the simulator and it is working as expected.

Screen.Recording.2026-08-18.at.5.28.41.PM.mov

[brian-smith-tcril]

it is working as expected

The expectation is that the sidebar closes when rotating the device? Also that video appears to show a full refresh on rotate which I wouldn't expect on mobile hardware.

[Agrendalath]

@brian-smith-tcril, this PR does not modify the existing behavior - i.e., the sidebar closes when rotating the device (even though it's indeed confusing). This only fixes the listed issues that are clear bugs that do not require an extended product review.

Also that video appears to show a full refresh on rotate which I wouldn't expect on mobile hardware.

It appears to be a simulator behavior; I cannot reproduce it on a physical device.