Stylus supports three kinds of comments: single-line, and multi-line comments, and multi-line buffered comments.

Single-line comments look like JavaScript comments, and do not output in the resulting CSS:

// I'm a comment!
body
  padding 5px // some awesome padding

Multi-line comments look identical to regular CSS comments. However, they only output when the compress option is not enabled.

/*
 * Adds the given numbers together.
 */

add(a, b)
  a   b

Multi-line comments which are not suppressed start with /*!. This tells Stylus to output the comment regardless of compression.

/*!
 * Adds the given numbers together.
 */

add(a, b)
  a   b