I’m sorry I should have updated my message when I fixed the problem.
The expanded elements were not working because I had put them into three columns for the full-size site and then had moved them down to one column for the mobile site. They would not expand due to something with the fixed column width.
To solve the problem, I made two versions of the collapsible elements. One in columns for the full-size site and one without columns for the mobile site. I used “display: block” or “display: none” in my CSS as needed to show the appropriate divs, which is why it works now.
I’d be happy to share the first set of code if anyone wants to explore further why it didn’t work in my first attempt.
