url - CSS: Style external links
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: '↗️';
}