add focus styles for when tabbing

media/jetpack/css/UI.Editor_Menu.css

@@ -91,7 +91,8 @@ form.UI_Editor_Menu_Descendant {
 			-moz-border-radius-bottomleft: 0;
 		}
 
-	.UI_Editor_Menu_Button a:hover {
+	.UI_Editor_Menu_Button a:hover,
+    .UI_Editor_Menu_Button a:focus {
 		background: -moz-linear-gradient(270deg, #FBFBFB, #E6E8EB);
 		text-decoration: none;
 	}

media/jetpack/css/UI.Layout.css

@@ -32,7 +32,7 @@ a:link {
 	outline: none;
 }
 
-a:hover {
+a:hover, a:focus {
 	text-decoration: underline;
 }