Style-to-Class Mode

Pass a StyleClassMap to replace inline color styles with CSS class names, producing a shared stylesheet for all code blocks.

The workflow

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classMap := nuri.NewStyleClassMap()
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html1, _ := h.CodeToHTML(ctx, goCode, nuri.CodeToHTMLOptions{
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  Lang: "go", Theme: "nord", ClassMap: classMap,
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})
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html2, _ := h.CodeToHTML(ctx, jsCode, nuri.CodeToHTMLOptions{
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  Lang: "javascript", Theme: "nord", ClassMap: classMap,
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})
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css := classMap.CSS()

The StyleClassMap accumulates unique style combinations across multiple h.CodeToHTML() calls. classMap.CSS() returns the combined stylesheet covering all code blocks.

How it works

Each unique style combination gets a deterministic class name derived from an FNV-64a hash. The format is _s_ followed by a hex string (for example, _s_4a3f9c2b1d0e7f8a).

Without ClassMap, a token <span> looks like:

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<span style="color:#ff7b72;font-style:italic">func</span>

With ClassMap, the same token becomes:

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<span class="_s_4a3f9c2b1d0e7f8a">func</span>

The <pre> element's background and foreground styles are also replaced with a class name. Identical style combinations across different code blocks, languages, or themes produce the same class name.

The generated stylesheet

classMap.CSS() returns one rule per unique style combination, sorted by class name:

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._s_1a2b3c4d5e6f7890 { color: #79c0ff }
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._s_4a3f9c2b1d0e7f8a { color: #ff7b72; font-style: italic }
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._s_7e8f9a0b1c2d3e4f { color: #a5d6ff }

Embed this stylesheet in a <style> tag or serve it as a static CSS file.

When to use

• CSP policies that forbid inline style attributes
• Cacheable stylesheets across pages that share the same theme
• Smaller HTML when many tokens share the same style (one class name vs. a full inline declaration on every <span>)

Next steps

• Line Decorations to highlight, focus, and diff lines
• Transformers for notation comments and meta string highlighting