<svg xmlns="http://www.w3.org/2000/svg" xmlns:h="http://www.w3.org/1999/xhtml" width="200" height="200">
  <title>A marker with a zero viewBox is not rendered</title>
  <h:link rel="help" href="https://w3c.github.io/svgwg/svg2-draft/coords.html#ViewBoxAttribute"/>
  <h:link rel="match" href="viewBox-zero-disables-rendering-marker-ref.svg"/>
  <h:meta name="assert" content="A marker whose viewBox has a zero width disables rendering; only the path stroke is painted, not the marker."/>
  <defs>
    <marker id="m" viewBox="0 0 0 100" markerWidth="100" markerHeight="100" refX="0" refY="0" markerUnits="userSpaceOnUse">
      <rect width="100" height="100" fill="green"/>
    </marker>
  </defs>
  <path d="M20,20 L180,20" stroke="black" stroke-width="1" fill="none" marker-start="url(#m)"/>
</svg>