src/language-js/embed.js/isCssProp
function isCssProp(path) {
  const parent = path.getParentNode();
  const parentParent = path.getParentNode(1);
  return (
    parentParent &&
    parent.type === "JSXExpressionContainer" &&
    parentParent.type === "JSXAttribute" &&
    parentParent.name.type === "JSXIdentifier" &&
    parentParent.name.name === "css"
  );
}