text: export class DefaultTheme {
      constructor() {
          this.$el = document.createElement('div');
      }
      createControls() {
          const $controls = document.createElement('div');
          $controls.classList.add('controls');
          this.$el.appendChild($controls);
          return this;
      }
      createProgress() {
          const $progress = document.createElement('div');
          $progress.classList.add('progress', 'mb-2', 'bg-white');
  
          const $bar = document.createElement('div');
          $bar.classList.add('progress-bar', 'bg-success');
  
          $progress.appendChild($bar);
  
          this.$el.querySelector('.controls').appendChild($progress);
          return this;
      }
      addButton(name, label, cb) {
          const $button = document.createElement('button');
          $button.textContent = label;
          $button.classList.add('btn', 'btn-primary', 'mr-2', name);
          $button.addEventListener('click', cb);
          this.$el.querySelector('.controls').appendChild($button);
          return this;
      }
      render($target) {
          $target.append(this.$el);
          return this.$el;
      }
  }
  