Fixed css issue with sidenav not extending to bottom of page when dashboard requires scrolling, #1483

src/css/less/sidemenu.less

@@ -1,7 +1,12 @@
+.sidemenu-canvas {
+  position: relative;
+}
+
 .sidemenu-wrapper {
   position: absolute;
   display: none;
   top: 0;
+  bottom: 0;
   left: 0;
   width: 200px;
   background: @bodyBackground;