Bug: Character vertical alignment is inconsistent after large downward scrolls on Firefox

[cakoose]

Prerequisites

• I have searched for duplicate or closed issues
• I have read the contributing guidelines

Describe the issue

• The f, i, and d characters have a lower baseline than the other characters.

This could be a Firefox bug. Reporting it here because:

• Maybe there's a way to work around it.
• I don't understand the mechanism. Maybe someone who does can provide a better bug report to Firefox than I can.

Larger screenshot

Reproduction

1. Load the example DiffsHub URL in Firefox: https://diffshub.com/oven-sh/bun/pull/30412
2. Text looks fine.
3. Grab the scrollbar and scroll really far down.
4. Vertical alignment is inconsistent. (If you don't see the issue, try scrolling down again. Doesn't happen every time, but happens about 50% of the time.)

It seems to only happen when I scroll down.

• If I scroll up, sometimes the problem goes away.
• Once the problem goes away, I can't get the problem to reappear by scrolling up. But scrolling down again usually causes it to reappear.

I can't reproduce this problem on Chrome.

What browser(s) are you seeing the problem on?

Firefox

What version of @pierre/diffs are you using?

Whatever is on DiffsHub today. Plus: Firefox 153.0.3 (aarch64), macOS 26.6.1 (25G76)

[amadeus]

lmao this is wild! most definitely some deep firefox bug with font rendering, will have to do a bit of research on if there's a workaround or not.