fix(view): assignment checkbox

[huyenltnguyen]

Checklist:

• I have read and followed the contribution guidelines.
• I have read and followed the how to open a pull request guide.
• My pull request targets the main branch of the repo.
• I have tested these changes locally on my machine.

Closes #1503

Tested on Odin - Learn HTML Foundations - Lesson A

Before	After

[Sembauke]

We will need to add a Material widget as its parent. If you check the mobile app on your phone you will see what it used to look like.

[Sembauke]

Also, I had this one open #1501 - might be useful?

[huyenltnguyen]

If you check the mobile app on your phone you will see what it used to look like.

The prod version has an a11y issue, in that the white link text on a gray background produces a low contrast ratio.

My attempt to fix it is simply removing the gray background. If we want to keep it, we'd need to dynamically change the link text color (and I think that would require calling parser.parse() conditionally, with the link text color as an argument).