Accessibility

Accessibility checks

• Markdown image or ::image without alternative text;
• image-* layout without image=;
• empty heading, skipped heading level (h1 → h3);
• Mermaid diagram without title="…" (the title becomes the accessible name of the SVG).

Syntax diagnostics

Invalid front matter or front matter that looks like a slide, unknown layout or transition, malformed slide JSON, duplicated slide id. Every diagnostic points to a line of the source file.