MD Bookmarks: Simplify and improve consistency of CSS

chrome/browser/resources/md_bookmarks/item.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="chrome://bookmarks/actions.html">
 <link rel="import" href="chrome://bookmarks/shared_style.html">
 <link rel="import" href="chrome://bookmarks/store_client.html">
 
 <dom-module id="bookmarks-item">
   <template>
     <style include="shared-style">
       :host {
         -webkit-padding-start: 20px;
         -webkit-user-select: none;
         align-items: center;
         cursor: pointer;
         display: flex;
         flex-direction: row;
         height: 40px;
         position: relative;
       }
 
       :host([is-selected-item_]) {
-        background-color: rgb(225, 235, 253);
+        background-color: var(--highlight-color);
       }
 
       #website-title {
         color: var(--primary-text-color);
         flex: 1;
         overflow: hidden;
         text-decoration: none;
         text-overflow: ellipsis;
         white-space: nowrap;
       }
 
+      #icon-wrapper {
+        -webkit-margin-end: 20px;
+        color: var(--secondary-text-color);
+        display: flex;
+        height: 20px;
+        width: 20px;
+      }
+
       #icon {
         background-repeat: no-repeat;
         height: 16px;
         margin: 2px;
+        width: 16px;
       }
 
-      #icon-wrapper {
-        -webkit-margin-end: 20px;
-        height: 20px;
-        width: 20px;
-      }
-
-      .more-vert-button {
+      button.more-vert-button {
         -webkit-margin-end: 12px;
       }
-
-      iron-icon {
-        --iron-icon-height: 20px;
-        --iron-icon-width: 20px;
-        color: var(--secondary-text-color);
-      }
-      </style>
+    </style>
     <div id="icon-wrapper">
-      <iron-icon id="folder-icon" icon="cr:folder"
-          hidden$="[[!isFolder_]]">
+      <iron-icon id="folder-icon" icon="cr:folder" hidden$="[[!isFolder_]]">
       </iron-icon>
       <div id="icon" hidden$="[[isFolder_]]"></div>
     </div>
     <div id="website-title">
       [[item_.title]]
     </div>
     <button is="paper-icon-button-light" class="more-vert-button"
         on-click="onMenuButtonClick_" on-dblclick="onMenuButtonDblClick_">
       <div></div>
       <div></div>
       <div></div>
     </button>
   </template>
   <script src="chrome://bookmarks/item.js"></script>
 <dom-module>