Troubleshooting and supported behavior

Symptom	Action
Import cannot be found	Install with %pip in the active notebook, then restart the kernel.
Notebook output is unstyled	Trust the notebook or re-run its display cells. Some hosted platforms strip CSS.
Text uses a system font	The output carrying the fonts was cleared. Run deck.styles() once, or re-run the first lecture cell.
Old fonts or colors after upgrading	Restart the kernel and re-run the display cells. Saved outputs keep the HTML they were created with.
Components appear twice in an export	Your notebook host does not report cell ids. Use id="..." on components, or deck.clear() and run in order.
SQL / Java / C++ has no syntax colors	Install the [highlight] extra. Plain-text fallback remains supported.
Arabic text looks disconnected	Do not add letter spacing to Arabic in custom CSS; the library avoids it automatically.
Quiz or trace steps do not respond	Some hosts remove form controls from untrusted output. Trust the notebook or use the exported HTML.
Answers missing from a printed handout	Expand the answers before printing, or use export_pdf() which expands them.
docs says documentation is missing	In a source checkout, run python tools/build_docs.py. Installed releases include the built site.

Support scope

The core renderer runs without IPython or Pygments. Display and re-run tracking are verified in JupyterLab 4; Notebook 7 and VS Code use the same protocol. Modern CSS (container queries, :has(), logical properties, color-mix()) requires a browser from 2023 or later. Colab and other hosted services may restrict HTML; validate before teaching.

Displayed code is never executed by the renderer. Export includes only the deck’s components.

Keep your lecture reproducible

Record the package version used for a course. Before distributing a revised handout, restart the kernel, run all cells, then export.