[gmatossian]

Topic authors currently have no concrete diagram style default and can silently get different fonts even when copying existing SVG declarations. Define the reviewed Plus Jakarta Sans / JetBrains Mono and sentence-case treatment, with the collection diagrams' restrained palette and outlines, and provide an editable SVG starter whose licensed fonts work offline.

Diagram scale comes from named font sizes, weights, and suggested padding/gaps. Nodes and canvas follow their content; no standard width, maximum width, or aspect ratio sets the size. The authoring guide links the specification, starter, exception process, and rendered-output checks. Existing Topic diagrams and the application/generator remain unchanged.

Closes #125.

Verification and review

• npm run check passed locally under pinned Node 24, including 38 end-to-end browser tests.
• Offline starter checks passed in Chromium, Firefox, and WebKit at wide and narrow content sizes: no external requests, text within padding, editable labels, and supporting text preserved at its natural 14px display size in the narrow sample.
• Chromium reported the intended embedded/custom fonts; removing each embedded font changed actual-image pixels. Firefox/WebKit image pixels matched a reference with the fonts loaded.
• SVG parsing, pinned font SHA-256 hashes, complete upstream license notices, documentation links/fragments, and git diff --check passed.
• Codex performed the implementation and deliberate complete-diff review before push. No independent reviewer was selected for this bounded documentation/static-example change; no remaining blocking findings were identified.

The starter embeds Latin font subsets. The notes explain checking added symbols/scripts for coverage and preparing additional licensed coverage when needed. This does not change the app's general font-loading strategy or add dependencies.

The owner delegated conditional merge after readiness and successful Actions, followed by issue/project and branch cleanup.