RevealJS infinite loop when slide title matches Mermaid element id case-insensitively

Bug description

When creating a RevealJS output with a Mermaid diagram, you can craft a situation where the deck mysteriously loops. This happens when you have a Mermaid diagram containing elements with IDs that match (case-insensitively) a slide header.

It's easy to get into this situation without realizing it. You can work around it easily if you're aware of this pitfall, perhaps by prefixing all your mermaid diagram's ID strings.

Steps to reproduce

• Create index.qmd:

---
title: "Demo: looping slide deck"
subtitle: "💫 Wheee! 💫"
format:
  revealjs: default
---

## Foo

```{mermaid}
gantt
  Foo     :active, magicstring, 2024-01, 2024-02 
```


## Magicstring

This header :point_up: is critical. If I change one character, the bug no
longer reproduces. It must match, case-insensitive, the ID of an element in the
Mermaid diagram.  Any string will work. Case doesn't matter.

**This slide will never be displayed; instead, the slide deck will loop from
the beginning.**

The content below this point doesn't matter.


# More slides!

---

Something!

• quarto render index.qmd
• Open index.html
• Try to access the string with the header "Magicstring"

See also: https://github.com/mfisher87/sscce-quarto-slides-loop

Expected behavior

I will be able to access the slide with the header "Magicstring"

Actual behavior

The slide deck starts from the beginning when I attempt to access that slide.

Your environment

• IDE: vim
• OS: Pop!_OS 22

Quarto check output

$ quarto check
Quarto 1.5.56
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.2.0: OK
      Dart Sass version 1.70.0: OK
      Deno version 1.41.0: OK
      Typst version 0.11.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.5.56
      Path: /opt/quarto/bin

[✓] Checking tools....................OK
      TinyTeX: v2023.11
      Chromium: (not installed)

[✓] Checking LaTeX....................OK
      Using: TinyTex
      Path: /home/robatt/.TinyTeX/bin/x86_64-linux
      Version: 2023

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.10.14 (Conda)
      Path: /home/robatt/.local/share/miniforge3/bin/python
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with conda install jupyter

[✓] Checking R installation...........(None)

      Unable to locate an installed version of R.
      Install R from https://cloud.r-project.org/

Start by rendering the reported index.qmd with quarto render index.qmd and inspect the generated index.html in RevealJS. Reproduce the case-insensitive match between the Magicstring slide header and the Mermaid element ID; done means the slide is reachable without restarting the deck.