PDF: Tweak font-size and colors to more closely match other MD WebUI

chrome/browser/resources/pdf/elements/viewer-page-selector/viewer-page-selector.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. */
 
 :host {
   color: #fff;
-  font-size: 94.4%;
+  font-size: 123%;
 }
 
 :host ::selection {
   background: rgba(255, 255, 255, 0.3);
 }
 
 #pageselector {
   --paper-input-container-underline: {
     visibility: hidden;
   };
@@ skipping 24 matching lines @@
   padding: 0 3px;
 }
 
 #pagelength-spacer {
   display: inline-block;
   text-align: start;
 }
 
 #slash,
 #pagelength {
-  font-size: 76.5%;
+  font-size: 81%;
 }