Across the site, sr.ht uses mistletoe for rendering Markdown. It implements CommonMark, which is much more well-defined than the original Markdown specification.

Additionally, some extensions to CommonMark are used.

• Plain link URLs (of the form <scheme>://<path>) and plain e-mail addresses (of the form <name>@<domain>) can be used, and they will be turned into the appropriate links (for e-mail addresses, this prepends mailto:).

#Post-processing

Rendered HTML is post-processed so that it only consists the following tags and attributes (in the format tags...: attributes...)

• a: href, title
• abbr: title
• acronym: title
• b
• blockquote
• code
• dd
• div
• dl
• dt
• em
• h1, h2, h3, h4, h5, h6: id
• i
• img: alt, height, width, src (only HTTP/HTTPS/local URLs)
• input: type=checkbox, checked, disabled
• li
• ol
• p
• pre
• q
• span
• strong
• table
• tbody
• td
• th
• thead
• tr
• ul

All tags can have the attributes class, style, colspan and rowspan. The only allowed classes are row, col-md-*, and form-control.

Here are valid style attributes:

• margin
• padding
• text-align
• font-weight
• text-decoration
• padding-{left,right,bottom,top}
• margin-{left,right,bottom,top}