Add the Quickoffice viewer toolbar polymer elements.

elements/viewer-button/viewer-button.css

+/* Copyright 2013 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file. */
+
+#icon {
+  background-position: center center;
+  background-repeat: no-repeat;
+  background-size: 100% 100%;
+  height: 100%;
+  width: 100%;
+}
+
+:host {
+  -webkit-user-select: none;
+  background-image: linear-gradient(rgb(60, 80, 119), rgb(15, 24, 41));
+  border: 1px solid rgb(11, 9, 16);
+  cursor: default;
+  display: inline-block;
+  height: 36px;
+  margin: 0;
+  width: 43px;
+}
+
+:host(:focus:host) {
+  outline: none;
+}
+
+:host(:hover:host) {
+  background-image: linear-gradient(rgb(73, 102, 155), rgb(32, 52, 95));
+}
+
+:host(.latchable.polymer-selected:host),
+:host(:active:host) {
+  background-color: rgb(75, 103, 156);
+  background-image: none;
+}