Fragments and animations

Fragments reveal content step by step. VS Code Reveal supports the attribute syntax without requiring raw HTML:

- Establish the idea {.fragment}
- Add emphasis {.fragment .highlight-red}
- Reveal this last {.fragment data-fragment-index="2"}

Move this paragraph later {.fragment .fade-up}

Set revealjs.incremental to true to reveal list items one at a time by default.