HTML mode

glu can convert HTML files directly to PDF. The same default stylesheet as in Markdown mode applies (serif, A4, 2cm margins); your own CSS layers on top and overrides it.

glu page.html    # → page.pdf

glu detects the mode by the file extension: .html or .htm for HTML mode.

Features

HTML mode supports:

Full HTML document structure (<!DOCTYPE html>, <html>, <head>, <body>)
<style> tags in <head> (including @page rules)
<link rel="stylesheet"> for external CSS files
CSS class and element selectors
The CSS properties of the htmlbag reference: fonts, borders, padding, backgrounds, page setup
Tables, lists, headings, paragraphs
Inline styles

Example

<!DOCTYPE html>
<html>
<head>
    <style>
        @page { size: a5; margin: 2cm; }
        body { font-family: serif; font-size: 10pt; }
        h1 { color: #336699; font-size: 20pt; }
        .highlight {
            border: 1pt solid #336699;
            padding: 6pt;
            border-radius: 3pt;
        }
    </style>
</head>
<body>
    <h1>Report</h1>
    <p>This PDF was generated from an HTML file.</p>
    <div class="highlight">
        <p>This section has a <strong>blue border</strong>.</p>
    </div>
</body>
</html>

Run with:

glu report.html    # → report.pdf

Barcodes

glu can generate barcodes directly as vector graphics in the PDF, with no external images needed. Use the <barcode> element in HTML or Markdown:

<barcode type="code128" value="ABC-123" width="4cm" height="1cm"/>

Supported types

Type	Attribute value	Description
EAN-13	`ean13`	13-digit product barcode
Code 128	`code128`	Variable-length alphanumeric barcode
QR Code	`qr`	2D matrix barcode

Attributes

Attribute	Required	Description
`type`	yes	Barcode type (`ean13`, `code128`, `qr`)
`value`	yes	The data to encode
`width`	no	Width (default: `3cm`)
`height`	no	Height (default: same as width). For QR codes, height is always equal to width.
`eclevel`	no	QR error correction level: `L`, `M` (default), `Q`, or `H`

Examples

EAN-13 barcode:

<barcode type="ean13" value="4006381333931" width="4cm" height="2cm"/>

QR code with high error correction:

<barcode type="qr" value="https://www.example.com" width="3cm" eclevel="H"/>

In Markdown, where raw HTML is supported, the same element works directly:

# My Product

<barcode type="code128" value="PROD-42" width="5cm" height="1cm"/>

Scan the barcode above for product details.

Differences from Markdown mode

Feature	Markdown mode	HTML mode
Default stylesheet	Built-in (serif, A4, margins)	Same built-in stylesheet
PDF bookmarks	h1 and h2 share the top level, h3+ collapsed	Nested 1:1 by heading level
Metadata	YAML frontmatter	`<title>`, `<meta>` and `lang`, see Standards
Attachments	`attachments:` in the frontmatter	Companion `.lua`, see Attachments
Lua blocks	```{lua}	Not supported (use companion `.lua`)
Inline expressions	`{= expr =}`	Not supported
Go templates	`--template` flag	Not supported
`@page` rules	Via frontmatter or CSS file	Via `<style>` or `<link>`

HTML mode is ideal when you need full control over the document structure and styling, or when converting existing HTML content to PDF.

Beyond HTML

Styling with CSS: the default stylesheet, the order of stylesheets, margin boxes, counters, leaders and cross references.
Math: <math> elements with OpenType MATH fonts.
Standards: <meta name="pdf-format"> for tagged, archival and e-invoice PDFs.
Lua in documents: a companion file with callbacks.
Print-ready PDF: PDF/X, spot colors, overprint, bleed and crop marks.

Markdown Styling with CSS