For some reason, a backdrop filter makes an element force its children into itself. No idea why.
This is somewhat of an old page, despite the date on this page. I just haven't listed it anywhere. So, it's been a while since I've made this, and I don't remember the conclusion I came to. Take this with a grain of salt, but from what I remember, it's a WebKit bug, which Firefox then emulated for compatibility with pages. So we ain't getting this fixed any time soon.
If you have no idea what is going on here, it's okay; just learn webdev for ~6 months. Simple.