MD Bookmarks: Simplify and improve consistency of CSS

chrome/browser/resources/md_bookmarks/shared_style.html

 <link rel="import" href="chrome://bookmarks/shared_vars.html">
-<link rel="import" href="chrome://resources/cr_elements/hidden_style_css.html">
+<link rel="import" href="chrome://resources/cr_elements/shared_style_css.html">
 
 <dom-module id="shared-style">
   <template>
-    <style include="cr-hidden-style">
+    <style include="cr-shared-style">
       button.more-vert-button {
-        height: 36px;
         padding: 8px;
-        width: 36px;
       }
 
       button.more-vert-button div {
         border: 2px solid var(--secondary-text-color);
         border-radius: 2px;
         margin: 1px 8px;
         pointer-events: none;
         transform: scale(0.8);
       }
 
       hr {
         background: rgba(0, 0, 0, 0.11);
         border-width: 0;
         height: 1px;
         margin: 8px 0;
       }
 
-      paper-button {
-        height: 32px;
-        margin: 0;
-      }
-
       .drag-above::before,
       .drag-below::after {
         background-clip: padding-box;
         background-color: var(--interactive-color);
         border: 3px solid var(--interactive-color);
         border-bottom-color: transparent;
         border-radius: 0;
         border-top-color: transparent;
         box-sizing: border-box;
         content: '';
         display: block;
         height: 8px;
         left: 0;
         position: absolute;
         right: 0;
         z-index: 10;
       }
 
       .drag-above::before {
         top: 0;
         transform: translateY(-50%);
       }
 
       .drag-below::after {
         bottom: 0;
         transform: translateY(50%);
       }
 
       .drag-on {
-        background-color: rgba(66, 133, 244, 0.16);
+        background-color: var(--highlight-color);
       }
     </style>
   </template>
 </dom-module>