<select id="timezone" name="timezone" class="custom-select">

  <option value="Pacific/Honolulu">Pacific/Honolulu GMT-10:00</option>

  <option value="America/Anchorage">America/Anchorage GMT-9:00</option>

  <option value="America/Los_Angeles">America/Los_Angeles GMT-8:00</option>

  <option value="America/Boise">America/Boise GMT-7:00</option>

  <option value="America/Denver">America/Denver GMT-7:00</option>

  <option value="America/Phoenix">America/Phoenix GMT-7:00</option>

  <option value="America/Chicago">America/Chicago GMT-6:00</option>

  <option value="America/Detroit">America/Detroit GMT-5:00</option>

  <option value="America/New_York">America/New_York GMT-5:00</option>

</select>