Remove sticky-top class from side navigations

[marvinchin]

What is the purpose of this pull request? (put "X" next to an item, remove the rest)

• [x] Bug fix

Fix #818.

What is the rationale for this request?

The side navigations have unnecessarily high z-index, which causes it to be layered on top of other components.

What changes did you make? (Give an overview)

Remove the sticky-top bootstrap class which adds the high z-index, and use other css classes to retain the same positioning without increasing z-index.

Is there anything you'd like reviewers to focus on?

Testing instructions:
Build the TE3201 website with this branch, and navigate to http://127.0.0.1:8080/se-book-adapted/chapters/refactoring.html#refactoring. Use the searchbar. The page navigation should not appear above the search results.

Proposed commit message: (wrap lines at 72 characters)

Remove sticky-top class from side navigations

The sticky-top class increases the z-index of the side navigations to
1030. The high z-index is not necessary for the side navigations, and
has caused it to be layered on top of the dropdowns of other components.

Let's remove the sticky-top class from the side navigations, and use
other css classes to achieve the same positioning without the high
z-index.

[Chng-Zhi-Xuan]

Are you planning on reverting the changes to dropdown lists in vue-strap?

If so, it should be included in this PR (updated vue-strap.min.js).

[marvinchin]

Yes, I'm intending to make those changes!

Re-building and updating vue-strap is done in our release procedure. Hence I feel like updating it should be done during release for consistency rather than in this PR (since there seems to be 2 logical parts to this - making changes to the vue-strap repo, and then updating the vue-strap dependency in the markbind repo).

What do you think about it?

[Chng-Zhi-Xuan]

As the changes were minimal for this PR, we can do the updating of vue-strap dependency on the next release.

For bigger PRs that cover features or bug fixes. Usually we require the updated vue-strap.min.js file within the PR in order for any feature / tests to work properly.

It is more for the reviewer's convenience, but not necessary for this PR :P

[marvinchin]

Understood, thanks for the clarification! 🙂

[Chng-Zhi-Xuan]

Tested with the updated vue-strap.min.js file from MarkBind/vue-strap#104. Works fine as it should 👍