Custom styles
Author JSON style files, validate them with the schema, and compare cookbook screenshots.
Custom styles are plain JSON files passed to --style. Keep them in source control, add a seed when the style uses sketch variation, and validate the file before using it from an untrusted source.
am render diagram.mmd --format png --style examples/styles/transit-route-map.style.json --seed 11 --output diagram.pngUse the public schema at /schemas/style-spec.schema.json. The same file is exported from the npm package as agentic-mermaid/style-spec.schema.json, so editors can map either the hosted URL or the package export.
Cookbook examples
The package ships complete JSON files under examples/styles/. These three examples cover the uncovered clusters that work with the current StyleSpec: route-map semantics, retro editorial palettes, and page/backdrop treatments.
transit-route-map.style.json stresses thick connectors, rounded bends, compact station labels, and group labels.
mid-century-report.style.json uses palette, solid fills, typography, corners, and section bands without a custom renderer.
star-chart-atlas.style.json tests dark-page tokens, grid backdrop, pale strokes, and serif labels.Validation
The schema catches file shape in editors. Runtime code should still call validateStyleSpec(json); the CLI does this for .json files passed through --style.