attr-strip-heading

Whitespace immediately before a consumed {attr} on a heading-opener line is stripped from the heading text — no trailing spaces leak into Text value

§12.1

Input

== Start Heading  {.red}

Output AST

- type: Section
  level: 2
  heading:
    - type: Text
      value: Start Heading
  attributes:
    - key: class
      value:
        - red