{# Tell the server which clock the user reads the page by.

   Timestamps are stored in UTC; the GUI shows them local, and
   `created:` in the host search means the user's day. The browser is
   the only place that knows the timezone, so it writes the IANA name
   plus the current UTC offset into a cookie that
   `application.helpers.timezone` reads back. Nothing breaks without
   it — the page then renders in UTC, as it always did. #}
<script>
(function () {
  try {
    var resolved = Intl.DateTimeFormat().resolvedOptions();
    var name = (resolved && resolved.timeZone) ? resolved.timeZone : '';
    // `Europe/Berlin|-120`. The offset is the fallback for a server
    // without a timezone database; it is written unencoded because
    // every character of both halves is a legal cookie character.
    var value = name.replace(/[^A-Za-z0-9_+\/-]/g, '') + '|'
                + new Date().getTimezoneOffset();
    if (document.cookie.indexOf('syncer_tz=' + value) === -1) {
      document.cookie = 'syncer_tz=' + value
        + ';path=/;max-age=31536000;SameSite=Lax'
        + (location.protocol === 'https:' ? ';Secure' : '');
    }
  } catch (err) {
    /* No Intl, no cookies, no problem — the page stays on UTC. */
  }
})();
</script>