format(contents, section, axis) {
    var formating;

    if (this.name === "pre-paginated") {
      formating = contents.fit(this.columnWidth, this.height, section);
    } else if (this._flow === "paginated") {
      formating = contents.columns(this.width, this.height, this.columnWidth, this.gap, this.settings.direction);
    } else if (axis && axis === "horizontal") {
      formating = contents.size(null, this.height);
    } else {
      formating = contents.size(this.width, null);
    }

    return formating; // might be a promise in some View Managers
  }
Apply Css to a Document
@param  {Contents} contents
@return {Promise}