Improve UI for unpacked extensions failing to load

chrome/browser/resources/extensions/extension_error_overlay.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. */
 
 #extension-error-overlay {
   max-width: 100%;
 }
 
 #extension-error-overlay .content-area {
   display: flex;
   flex-direction: column;
 }
 
 .extension-error-overlay-runtime-content {
   flex: none;
 }
 
-#extension-error-overlay .highlighted-source {
+#extension-error-overlay .extension-code-highlighted-source {
   background-color: rgba(255, 195, 200, 255);
 }
 
 #extension-error-overlay-code {
- -webkit-margin-after: 10px;
-  border: 1px solid #ccc;
-  display: flex;
-  font-family: monospace;
+  -webkit-margin-after: 10px;
   font-size: 1.2em;
-  overflow: auto;
-  white-space: pre;
 }
 
-#extension-error-overlay-code > * {
-  padding: 5px;
-}
-
-#extension-error-overlay-source {
+#extension-error-overlay .extension-code-source {
   color: #555;
 }
 
-#extension-error-overlay-line-numbers {
-  align-self: flex-start;
-  background-color: rgba(240, 240, 240, 1);
-  border-right: 1px solid #ccc;
-  color: rgba(128, 128, 128, 1);
-  flex-shrink: 0;
-  text-align: right;
-}
-
 .extension-error-overlay-context {
   -webkit-margin-after: 10px;
   font-size: 1.1em;
 }
 
 .extension-error-overlay-stack-trace-list {
   list-style-type: none;
   padding: 0;
 }
 
@@ skipping 15 matching lines @@
   cursor: pointer;
 }
 
 .extension-error-overlay-stack-trace-list li:hover {
   background-color: #eee;
 }
 
 .extension-error-overlay-stack-trace-list li.extension-error-active {
   background-color: rgba(0, 100, 255, 0.1);
 }