Term is rendered partially hidden in containers with overflow=hidden/scroll

### What is the problem this feature will solve?

In some cases, when YFM is rendered in container with size not much larger than YFM-block itself, opening term can cause the scroll appearance or it can be rendered almost hidden behind the parent block border

### What is the feature you are proposing to solve the problem?

Add opportunity to render term definition element inside body element, so that it can be fully visible

### What alternatives have you considered?

Hacks from https://github.com/w3c/csswg-drafts/issues/4092, but they don't work in some cases