Make the options menu keyboard navigatable. Hide the menu when the...

chrome/browser/resources/new_new_tab.css

 html {
   /* This is needed because of chrome://theme/css/new_tab.css */
   height: 100%;
 }
 
 body {
   margin: 0;
 }
 
 #main {
@@ skipping 615 matching lines @@
   -webkit-user-select: none;
   position: absolute;
   right: 0;
   left: auto;
   top: 53px; /* Position this below the option button. The option button
                 is positioned 35px from the top and has a height of 17px. We add
                 one to get some spacing there as well: 35 + 17 + 1 = 53 */
   cursor: default;
   pointer-events: all;
   min-width: 175px;
-  outline: 0;
 }
 
 html[dir='rtl'] #option-menu {
   right: auto;
   left: 0;
 }
 
 #option-menu > div {
   padding: 3px 8px;
   overflow: hidden;
   text-overflow: ellipsis;
 }
 
-#option-menu > div:hover,
-#option-menu > div:focus {
+#option-menu > [selected] {
   background-color: hsla(213, 66%, 57%, 1);
   color: white;
-  outline: none;
 }