a[href]:not(:where(
  /* exclude hash only links */
  [href^="#"],
  /* exclude relative but not double slash only links */
  [href^="/"]:not([href^="//"]),
  /* domains to exclude */
  [href*="//stackoverflow.com"],
  /* subdomains to exclude */
  [href*="//meta.stackoverflow.com"],
)):after {
  content: url("/static/images/external.svg");
}