Godot documentation website design breaks Firefox's built-in "highlight search matches on vertical scrollbar" functionality

**Your Godot version:** 4.0

**Issue description:** Godot documentation website design breaks Firefox's built-in "highlight search matches on vertical scrollbar" functionality.

**URL to the documentation page (if already existing):** https://docs.godotengine.org/en/stable/tutorials/scripting/gdscript/gdscript_basics.html

**Expected result:** pull up the gdscript_basics URL, hit ctrl+f, and search for the word "array" in the browser. Many purple match indicators should display on the browser's vertical scrollbar.

**Actual result:** pull up the gdscript_basics URL, hit ctrl+f, and search for the word "array" in the browser. Only one purple match indicator shows up, at the very bottom of the scrollbar.

As of the date of writing (2023-04-22) the "highlight search matches on vertical scrollbar" works OK in Chrome 109, but **not** Firefox 112.