<details> elements are auto-expanded and non-functional on older browsers

[toolness]

Here's what it looks like on IE11 when the page loads:

Hovering over the chevron shows the "pointing hand" icon, indicating that it's interactive, but actually clicking does nothing, since IE11 doesn't natively support <details>.

We could polyfill this element, but (A) that would involve some work that we might not have time for right now and (B) we also need to account for situations where the user is both on an old browser and one that isn't running our JS, so I think the easiest fix for now is just to style the page such that these elements appear always-expanded but don't appear to provide a "broken" chevron UI like they currently do.