Highlighted Lines Appearing Incorrectly from the Middle of the Page Onward

[EsmaeilSaleh]

Hi Next.js team,

I noticed that on the Mutating Data page, highlighted lines appear incorrectly from the middle of the page onward. It seems like the formatting might be off, causing unintended highlighting in the code blocks.

Steps to Reproduce:
1. Go to Mutating Data.
2. Scroll down to the middle of the page.
3. Observe that the highlighting in the code examples appears incorrect.

Expected Behavior:
The highlighted lines should accurately reflect the intended focus in the code examples.

Additional Notes:
It would be great if this could be corrected to ensure clarity in the tutorial. Thanks for looking into it!