src/language-css/utils.js/isKeyframeAtRuleKeywords
function isKeyframeAtRuleKeywords(path, value) {
  const atRuleAncestorNode = getAncestorNode(path, "css-atrule");
  return (
    atRuleAncestorNode &&
    atRuleAncestorNode.name &&
    atRuleAncestorNode.name.toLowerCase().endsWith("keyframes") &&
    ["from", "to"].includes(value.toLowerCase())
  );
}