Mobile tooltips are often hidden partly off screen

**Your Godot version:** N/A

**Issue description:**
Godot docs frequently use `` tags that show a tooltip with additional information when hovered on desktop browsers. For touch devices where hovering isn't possible, there's some CSS magic to show a custom tooltip when the word is tapped instead. This is great, but unfortunately the mobile tooltips in their current state often aren't usable in practice because **large parts of the tooltips end up off-screen or cut off at the table edge**.

I wanted to attach some screenshots, but image upload to GitHub is failing for me (seemingly because of CORS errors of all things??).

**URL to the documentation page:** Most, but for example: https://docs.godotengine.org/en/stable/classes/class_node.html#methods

Note: I have a proposed fix nearly ready for this, I'll put up a PR soon :)