document.addEventListener("DOMContentLoaded", function() {
  for (let details of document.getElementsByClassName('song-details')) {
    details.classList.add('collapsed');
  };

  for (let toggler of document.getElementsByClassName('add-song-button')) {
    toggler.classList.remove('collapsed');
    toggler.onclick = function() {
      this.style.display = "none";
      let n = toggler.dataset.songNumber;
      let details = document.getElementById('song-' + n + '-details');
      details.classList.remove('collapsed');
    }
  };
});