Kramdown Flavor

April 13, 2026 · View on GitHub

For content processed by kramdown, the default Markdown renderer for Jekyll sites. Extends standard flavor with kramdown-specific syntax support including Inline Attribute Lists (IALs), extension blocks, and definition lists.

Supported Patterns

Inline Attribute Lists (Block IALs)

Block IALs add attributes to the preceding block element. Standalone IAL lines are recognized as kramdown syntax and skipped by rules that would otherwise flag them:

# Heading
{:.highlight #custom-id}

```ruby
puts "Hello"

{:.language-ruby .numberLines}

Blockquote content {:#special-quote .emphasized}


### Span IALs

Span IALs attach attributes to inline elements. MD037 recognizes them to avoid false positives on emphasis spacing:

```markdown
*emphasized text*{:.red}
**bold text**{:#important}
[link](https://example.com){:target="_blank"}

Extension Blocks

Kramdown extension blocks ({::comment}, {::nomarkdown}, etc.) are treated as non-content regions. Content inside extension blocks is skipped by linting rules:

{::comment}
This content is hidden from rendering.
It can contain <div>HTML</div> or other syntax.
{:/comment}

{::nomarkdown}
<div class="custom">
  Raw HTML that kramdown won't process
</div>
{:/nomarkdown}

The shorthand close {:/} is also supported.

Options Directive

Kramdown options directives are recognized and skipped:

{::options parse_block_html="true" /}

Definition Lists

Definition lists use the : definition syntax:

Term 1
: Definition 1
: Another definition

Term 2
: Definition 2

Footnotes

Kramdown-style footnote definitions and references:

Text with a footnote[^1] reference.

[^1]: Footnote content here.

Abbreviations

Abbreviation definitions:

*[HTML]: HyperText Markup Language
*[W3C]: World Wide Web Consortium

End-of-Block Markers

The ^ character on its own line ends the current block:

First paragraph
^
Second paragraph starts a new block

Rule Behavior Changes

Rule	Standard Behavior	Kramdown Behavior
MD022	Check blanks around headings	Allow IALs immediately after headings
MD041	Check first line is heading	Skip IALs and extension blocks as preamble
MD051	Use GitHub anchor style	Default to kramdown anchor generation

Additionally, the filtered_lines() API supports skip_kramdown_extension_blocks() for rules that need to skip content inside {::comment} and {::nomarkdown} blocks.

Anchor Generation

When kramdown flavor is active, MD051 (link fragment validation) defaults to kramdown's anchor generation algorithm instead of GitHub's. This matches how Jekyll generates heading IDs.

To explicitly configure anchor style:

[MD051]
anchor-style = "kramdown"       # Pure kramdown style
# anchor-style = "kramdown-gfm" # Jekyll with GFM input

Configuration

[global]
flavor = "kramdown"

The jekyll alias is also accepted:

[global]
flavor = "jekyll"

Auto-Detection

Files with the .kramdown extension are automatically detected as kramdown flavor.

For Jekyll projects, add flavor = "kramdown" (or flavor = "jekyll") to your .rumdl.toml.

When to Use

Use the kramdown flavor when:

Building Jekyll sites that use kramdown as the Markdown renderer
Using kramdown-specific syntax like IALs, ALDs, or extension blocks
Documents contain {:.class} or {:#id} attribute syntax
Using kramdown's {::comment} or {::nomarkdown} extension blocks