[MD settings] shrink overscroll when scrolling up

chrome/browser/resources/settings/settings_main/settings_main.html

 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="/about_page/about_page.html">
 <link rel="import" href="/advanced_page/advanced_page.html">
 <link rel="import" href="/basic_page/basic_page.html">
 <link rel="import" href="/route.html">
 <link rel="import" href="/settings_page/main_page_behavior.html">
 <link rel="import" href="/settings_vars_css.html">
 
 <dom-module id="settings-main">
   <template>
     <style>
       #advancedToggle {
         @apply(--settings-actionable);
         align-items: center;
         display: flex;
-        margin-bottom: 24px;
+        margin-bottom: 3px;
         margin-top: 12px;  /* Part of a 48px spacer (33px + 12px + 3px). */
         min-height: 32px;
         padding: 0 12px;
       }
 
       #toggleContainer {
         align-items: center;
         display: flex;
         justify-content: center;
-        margin-bottom: -var(--settings-page-vertical-margin);
       }
 
       #toggleSpacer {
         padding-top: 33px;  /* Part of a 48px spacer (33px + 12px + 3px). */
       }
 
       iron-icon {
         -webkit-margin-start: 16px;
       }
 
@@ skipping 40 matching lines @@
     </template>
     <template is="dom-if" if="[[showPages_.about]]">
       <settings-about-page current-route="{{currentRoute}}">
       </settings-about-page>
     </template>
     <div id="overscroll"></div>
   </template>
   <script src="settings_main.js"></script>
   <script src="/search_settings.js"></script>
 </dom-module>