code: function attach() {
      const container = this.options.container;
  
      if (container instanceof HTMLElement) {
          const style = window.getComputedStyle(container);
  
          if (style.position === 'static') {
              container.style.position = 'relative';
          }
      }
  
      container.addEventListener('scroll', this._scroll);
      window.addEventListener('resize', this._scroll);
      this._scroll();
      this.attached = true;
  }
docs: Attaches the scroll event handler
  
  @return {void}