asciinema.org/app/views/asciicasts/_player.html.slim

.player class="#{size}-font"

javascript:
  $(function() {
    var playerClass = #{player_class.html_safe};
    var containerWidth = #{container_width || 'null'};

    window.player = new playerClass({
      el: $('.player'),
      speed: #{speed},
      benchmark: #{benchmark},
      model: new Asciinema.Asciicast(#{asciicast.html_safe}),
      containerWidth: containerWidth || $('.cinema .player').parent().width(),
      rendererClass: #{renderer_class.html_safe},
      autoPlay: #{auto_play},
      hud: #{hud}
    });
  });