gistfile1.txt

$list = $('.collections__list');
$item = $list.find('.list__item--is-selected');
$prev = $item.prev();
    
if ($(window).width() < 700) {
  // collections put whatever collection is selected at top of list on mobile
  $list.prependTo('.collections__list');
}

// collections put whatever collection is selected at top of list on mobile
$(window).resize(function() {
  if ($(window).width() < 700) {
    // collections put whatever collection is selected at top of list on mobile
    $prev.after($item);
  }
});