StyleSheet: ownerNode property
  The ownerNode property of the
  StyleSheet interface returns the node that associates this style sheet
  with the document.
  This is usually an HTML
  <link> or
  <style> element, but
  can also return a processing instruction node in the case of <?xml-stylesheet ?>.
Value
A Node object.
Examples
html
<html lang="en">
  <head>
    <link rel="stylesheet" href="example.css" />
  </head>
  <body>
    <button onclick="alert(document.styleSheets[0].ownerNode)">
      Show example.css's ownerNode
    </button>
  </body>
</html>
// Displays "object HTMLLinkElement"
Notes
  For style sheets that are included by other style sheets, such as with
  @import, the value of this
  property is null.
Specifications
| Specification | 
|---|
| CSS Object Model (CSSOM)  # dom-stylesheet-ownernode  | 
Browser compatibility
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