code: function getPreviewContainerStyle(options) {
          var preview_container_style = "";
  
          var padding_value = options.preview_padding;
          if (typeof padding_value === "number") {
              padding_value = [ padding_value ];
          }
          if (isArray(padding_value)) {
              preview_container_style += "padding: " + padding_value.join("px ") + "px !important; ";
          }
  
          if (options.background_color) {
              preview_container_style += "background-color: " + options.background_color + " !important; ";
          }
  
          return preview_container_style.replace(/\s$/, "") || undefined;
      }
docs: Generate value for the preview container "style" attribute
  @param {object} options
  @param {number|number[]} [options.preview_padding] Padding value(s) for preview container (4 or [4, 8], or [4, 0, 12, 8] etc.)
  @param {string} [options.background_color] Background color CSS value for both main showcase page and preview iframe pages
  @returns {string|undefined} Undefined value denies redundant attribute creating: $elem.attr("style", undefined)
  @todo enable string value for preview_padding (like "4px 8px")?