website/playground/markdown.js/codeBlock
function codeBlock(content, syntax) {
  const backtickSequences = content.match(/`+/g) || [];
  const longestBacktickSequenceLength = Math.max(
    ...backtickSequences.map(({ length }) => length)
  );
  const prettierIgnoreComment = "<!-- prettier-ignore -->";
  const fenceLength = Math.max(3, longestBacktickSequenceLength + 1);
  const fence = "`".repeat(fenceLength);
  return [prettierIgnoreComment, fence + (syntax || ""), content, fence].join(
    "\n"
  );
}