Got rid of the "released" class and made the pin icon depend on the sidebar state.

web/viewer.css

@@ -85,7 +85,7 @@ span#info {
   z-index: 1;
 }
 
-#sidebar.released {
+#sidebar {
   left: -290px;
   transition: left 0.25s ease-in-out 1s;
   -o-transition: left 0.25s ease-in-out 1s;
@@ -93,8 +93,8 @@ span#info {
   -webkit-transition: left 0.25s ease-in-out 1s;
 }
 
-#sidebar.pinned,
-#sidebar.released:hover {
+#sidebar:hover,
+#sidebar.pinned {
   left: 0px;
   transition: left 0.25s ease-in-out 0s;
   -o-transition: left 0.25s ease-in-out 0s;
@@ -109,17 +109,14 @@ span#info {
   width: 15px;
   height: 15px;
   background: center no-repeat;
+  background-image: url('images/pin_up.png');
 }
 
 #pinIcon:hover {
   background-color: rgba(255,255,255,0.35);
 }
 
-#pinIcon.released {
-  background-image: url('images/pin_up.png');
-}
-
-#pinIcon.pinned {
+#sidebar.pinned #pinIcon {
   background-image: url('images/pin_down.png');
 }
 

web/viewer.html

@@ -120,9 +120,9 @@
       <textarea id="errorMoreInfo" hidden='true' readonly="readonly"></textarea>
     </div>
 
-    <div id="sidebar" class="released">
+    <div id="sidebar">
       <div id="sidebarBox">
-        <div id="pinIcon" class="released" onClick="PDFView.pinSidebar()"></div>
+        <div id="pinIcon" onClick="PDFView.pinSidebar()"></div>
         <div id="sidebarScrollView">
           <div id="sidebarView"></div>
         </div>

web/viewer.js

@@ -168,7 +168,6 @@ var PDFView = {
   currentScale: kUnknownScale,
   currentScaleValue: null,
   initialBookmark: document.location.hash.substring(1),
-  pinState: false,
 
   setScale: function pdfViewSetScale(val, resetAutoSettings) {
     if (val == this.currentScale)
@@ -573,23 +572,7 @@ var PDFView = {
   },
 
   pinSidebar: function pdfViewPinSidebar() {
-    var sidebar = document.getElementById('sidebar');
-    var pinIcon = document.getElementById('pinIcon');
-
-    var oldClass = 'released';
-    var newClass = 'pinned';
-
-    if (this.pinState) {
-      oldClass = 'pinned';
-      newClass = 'released';
-    }
-
-    sidebar.classList.remove(oldClass);
-    pinIcon.classList.remove(oldClass);
-    sidebar.classList.add(newClass);
-    pinIcon.classList.add(newClass);
-
-    this.pinState = !this.pinState;
+    document.getElementById('sidebar').classList.toggle('pinned');
   },
 
   getVisiblePages: function pdfViewGetVisiblePages() {