Update incognito and guest browsing new tab page:

chrome/browser/resources/ntp4/guest_tab.css

 /* Copyright 2013 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
-body {
-  margin: 10px 8px;
+html {
+  background: #fafafa !important;
 }
 
-.icon {
-  -webkit-margin-end: 3px;
-  -webkit-margin-start: 6px;
+body {
+  font-family: Arial, sans-serif;
+  line-height: 1.5;
 }
 
-html[dir='ltr'] .icon {
-  float: right;
+h1 {
+  color: #000;
+  font-size: 1.7em !important;
+  font-weight: normal;
+  line-height: 1.2em;
+  margin: 0 0 .6em;
 }
 
-html[dir='rtl'] .icon {
-  float: left;
+a {
+  color: rgb(39, 110, 242);
+  text-decoration: none;
+}
+
+a:hover {
+  text-decoration: underline;
+}
+
+p {
+  margin: 0 0 1em;
 }
 
 .content {
-  background-color: #eee;
-  border-radius: 5px;
+  background-color: #fff;
+  border-radius: 2px;
+  box-shadow: 0 4px 6px 1px rgba(50, 50, 50, 0.14);
+  box-sizing: border-box;
   color: black;
-  margin-left: auto;
-  margin-right: auto;
-  margin-top: 66px;
-  max-width: 600px;
-  padding: 10px;
+  line-height: 1.5;
+  margin: 5.5em auto 0;
+  max-width: 630px;
+  padding: 30px 35px 30px 37px;
+  width: 100%;
 }
+
+.content p:last-child {
+  margin-bottom: 4px;
+}
+
+
+@media (max-width:700px) {
+  body {
+    margin: 3em 2em 2em;
+  }
+}
+
+@media (max-width:400px) {
+  body {
+    margin: 3em 1.5em 2em;
+  }
+}
+
+@media (max-height:480px) and (max-width:400px) {
+  .content {
+    margin: auto;
+  }
+}