onStepResize() {
      this.width = this.getBoundingClientRect().width;
      this.contentHeight = this.getContentHeight();
      if (this._prevWidth !== this.width || this.contentHeight !== this._prevContentHeight) {
        this._closeRespPopover();
      }
      this._prevWidth = this.width;
      this._prevContentHeight = this.contentHeight;
      this._calcCurrentBreakpoint();
    }
Handles resize in order to:
(1) sync steps' scroll offset and selection
(2) adapt navition step header
@private