enhance(curriculum): improve design

[caugner]

Summary

(MP-1106)

1. On the landing page, use a gray border for the modules on hover.
2. Add a margin above the "Resources:" section.
3. Reduce the margin below lists.
4. Use a consistent padding inside the "Notes:" boxes.
5. Reuse the module label background color for the sidebar/TOC highlighting.
6. Update the color of the "Notes:" boxes to match the hue of the sidebar/TOC highlighting (only dark theme).
7. Add consistent marging between lists and paragraphs in "Notes:" boxes.
8. Reduce the left padding of lists in "Notes:" boxes.

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Screenshots

Before

After

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How did you test this change?

Ran yarn dev and viewed http://localhost:3000/en-US/curriculum/ locally.