Material PDF: Fix inconsistent behaviour in page selector, update styling

chrome/browser/resources/pdf/elements/viewer-pdf-toolbar/viewer-pdf-toolbar.css

 /* Copyright 2015 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. */
 
 /* We introduce a wrapper animatable element and set the overflow since
  * core-transition interferes with the box-shadow from paper-shadow. */
 #animatable {
   overflow: visible;
 }
 
@@ skipping 22 matching lines @@
 }
 
 paper-progress {
   height: 56px;
   position: absolute;
   width: 100%;
   z-index: 3;
 }
 
 paper-progress::shadow #activeProgress {
-  background-color: rgb(27, 168, 243);
+  background-color: rgb(50, 54, 57);
 }
 
 paper-progress::shadow #progressContainer {
-  background-color: rgb(100, 181, 246);
+  background-color: rgba(0, 0, 0, 0.3);
 }
 
 paper-toolbar {
-  background-color: rgb(27, 168, 243);
+  background-color: rgb(50, 54, 57);
   color: rgb(241, 241, 241);
   font-size: 1.5em;
   height: 56px;
   padding-left: 1em;
   padding-right: 1em;
   z-index: 3;
 }
 
 paper-toolbar /deep/ ::selection {
-  background: rgb(187, 222, 251);
+  background: rgba(255, 255, 255, 0.3);
 }
 
 paper-toolbar /deep/ .toolbar-tools {
   height: 56px;
 }
 
 .invisible {
   visibility: hidden;
 }