Scrolling issue with internal links in HTML projects

I've been trying to break down this elusive internal link scrolling bug in the HTML environment for a while, but I haven't been able to make a simple case to reproduce. It happens in multiple browsers and machines on both Win and OSX, but sometimes things are fine.

I've experienced it in my own projects in the past, and I've seen it in a few other students' projects, but I can't come up with a good description except "sometimes internal links scroll to weird places".

Here's the best report and example I have received of the issue, I think: https://www.khanacademy.org/computer-programming/project-blog/6231853591298048

On my last check on my machine, this worked fine in Chrome (but in the past hasn't). In Firefox, clicking various internal links in that project will scroll the output window to incorrect places. The "One value" through "Four values" links don't scroll to the right lines, and the "To the bottom" link scrolls the page to a point slightly down from the top, actually landing in between two anchors.

Start by reproducing the linked project-blog example in Firefox and Chrome, focusing on the “One value” through “Four values” links and “To the bottom.” Establish a reliable test case for the incorrect anchor positions, then verify that internal links consistently land on their intended anchors across the reported browsers.

Written by the indexing model from the issue text.