EL2 Precalculus Checkit graph tweak

[siwelwerd]

Addresses #409.

Here's an example screenshot to compare against https://tbil.org/preview/precalculus/exercises/#/bank/EL2/1/

[github-actions[bot]]

🚀 Preview available 🚀

https://0232d67f.tbil.pages.dev

• Precalculus

• Calculus

• Linear Algebra