text: var body = document.querySelector('body');
  var controls = document.querySelector('#controls');
  var video_element = document.querySelector('#player');
  var player_container = document.querySelector('#player-container');
  var play_pause = document.querySelector('#play-pause');
  var volume = document.querySelector('#volume');
  var settings = document.querySelector('#settings');
  var la_url_toggle_btn = document.querySelector('#la-url-toggle-btn');
  var headers_toggle_btn = document.querySelector('#headers-toggle-btn');
  var add_header_btn = document.querySelector('#add-header-btn');
  var la_url = document.querySelector('#la-url');
  var reload_source_media_url_btn = document.querySelector('#reload-source-media-url-btn');
  var reload_source_la_url_btn = document.querySelector('#reload-source-la-url-btn');
  var volume_popup = document.querySelector("#volume-popup");
  var settings_form = document.querySelector("#settings-form");
  var settings_btn = document.querySelector("#settings-btn");
  var volume_btn = document.querySelector("#volume-btn");
  var la_url_form = document.querySelector("#la-url-form");
  var headers_form = document.querySelector("#headers-form");
  var media_url_form = document.querySelector("#media-url-form");
  var subtitles_url_form = document.querySelector("#subtitles-url-form");
  var media_url_toggle_btn = document.querySelector("#media-url-toggle-btn");
  var subtitles_toggle_btn = document.querySelector("#subtitles-toggle-btn");
  var media_url_input = document.querySelector("#media-url-input");
  var subtitles_url_input = document.querySelector("#subtitles-url-input");
  var fullscreen_toggle_btn = document.querySelector("#fullscren-toggle-btn");
  var load_subtitles_url_btn = document.querySelector("#load-subtitles-url-btn");
  var headers_reload_player_btn = document.querySelector("#headers-reload-player-btn");
  var loader = document.querySelector('#loader');
  var time = document.querySelector('#time');
  var duration = document.querySelector('#duration');
  var header_name_input = document.querySelector('#header-name');
  var header_value_input = document.querySelector('#header-value');
  var header_list_view = document.querySelector('#header-list-view');
  var headers_reload_player_btn = document.querySelector("#headers-reload-player-btn");
  
  var progress_range = new Range({
      target: document.querySelector('#progress'),
      target_classlist: 'collapsed',
      type: 'horizontal',
      min_value: 0,
      max_value: 100,
      value: 0,
      valueChanged: function(value) {
          video_element.currentTime = video_element.duration * (value / 100);
      }
  });
  
  var volume_range = new Range({
      target: document.querySelector('#volume-control-container'),
      target_classlist: '',
      type: 'vertical',
      min_value: 0,
      max_value: 100,
      value: 0,
      valueChanged: function(value) {
          player.setVolume(value / 100);
      }
  });
  
  var bitrate_selection = new Dropdown({
      target: document.querySelector('#bitrate-selection'),
      label: "Bitrate"
  });
  
  var playback_speed_selection = new Dropdown({
      target: document.querySelector('#playback-speed-selection'),
      label: "Playback speed",
      options: [
          {
              label: "x0.25",
              value: 0.25,
              selected: false
          },
          {
              label: "x0.5",
              value: 0.5,
              selected: false
          },
          {
              label: "x1",
              value: 1,
              selected: true
          },
          {
              label: "x1.25",
              value: 1.25,
              selected: false
          },
          {
              label: "x1.5",
              value: 1.5,
              selected: false
          },
          {
              label: "x2",
              value: 2,
              selected: false
          },
      ]
  });
  
  playback_speed_selection.addEventListener('change', function(e) {
      if(player != null) {
          player.setPlaybackRate(e.value);
      }
  });