Modals do not scale well, and not all buttons may be visible

Bug description and expecgted behavior

A clear and concise description of what the bug is, and what you expected to happen.

The Help and Quiz modals do not scale well. At certain window sizes or ratios, the close button may be hidden from view. The only way to see it again is to zoom out the browser.

Although the user can press the Escape key to exit, this is not available on mobile devices, and we want our app to be accessible to mobile devices.

The CSS should be adjusted to make sure that the popups do not exceed the window height. The popups are their own scroll areas, so that to view any hidden text or buttons, the user can scroll within the popup.

Steps to reproduce

A list of steps it takes to see this bug.

1. Open Help or Quiz modal
2. Resize window to be smaller.

Acceptance Criteria

A checklist of conditions that must be met for this task to be considered complete. How will we verify that it's done correctly?

• The buggy behavior no longer occurs.
• All related code passes the repository's workflow checks (linting, tests).
• The application runs without new errors after the changes are made.
• (If applicable) New automated tests have been added to cover the changes.

Additional context

Add any other context or screenshots about the bug here.

Start by locating the Help and Quiz modal components and their CSS, then reproduce the issue by resizing the browser window. Adjust the modal layout so it stays within the window height and scrolls internally, while keeping the close button visible. Run the repository workflow checks and verify both modals at smaller window sizes.