CopyAllStyles.js

function difference(a, b) {
  var out = {};

  if (!a || !b) return out;

  for (var key in a) {
    if (b.hasOwnProperty(key) && typeof(b[key]) !== "undefined") {
      if (a[key] !== b[key]) {
        console.log('difference', a[key], '|', b[key]);
        out[key] = a[key];
      }
    }
  }
  return out;
}

var styleObject = function(ele) {
  this.rootElement = ele;
  this.rootRules = this.getStyleObject(ele);
}

styleObject.prototype.getElementStyles = function(element) {
  return window.getComputedStyle(element, null);
}

styleObject.prototype.getStyleObject = function(element) {
  var obj = {},
      numFormat = /\D/g;
  var dcl = this.getElementStyles(element);

  for (var prop in dcl) {
    if (numFormat.test(prop) && typeof(dcl[prop]) !== "object" && 
        typeof(dcl[prop]) !== "function" &&
        prop !== "cssText" &&
        prop !== "length" &&
        dcl[prop].length > 0
        ) {
      obj[prop] = dcl[prop];
    }
  }
  return obj;
}
 
styleObject.prototype.applyToElements = function() {
  this.childApplyToElements(this.rootElement);
}

styleObject.prototype.childApplyToElements = function(parent) {
  for (var i = 0; i < parent.children.length; i++) {
    var child = parent.children[i];
    this.childApplyToElements(child);
  };
  this.applyToElement(parent);
}
 
styleObject.prototype.applyToElement = function(element) {
  var self = this;

  function dumpComputedStyles(elem) {
    var allStyles = [];
    
    var csObj = self.getElementStyles(elem);

    var diff;

    if (element === self.rootElement) {
      diff = self.rootRules;
    } else {
      diff = difference(csObj, self.rootRules);
    }

    console.log('diff', diff, element === self.rootElement);
    var len = diff.length;
    console.log('difffffff------------------>', diff);
    for (var prop in diff) {
      allStyles.push(prop+":"+diff[prop]);
    }

    // Finally, copy the element styles
    if (element.style) {
      allStyles.push(element.style.cssText);
    }
 
    return allStyles;
  }
 
  var allStyles = dumpComputedStyles(element)
  element.setAttribute('style', allStyles.join(';'));
}


var ele = document.getElementById('header');

var so = new styleObject(ele);
so.applyToElements();