We changed the (UX) design of the sidebar. The active and hover states of a menu item changed which makes them easier to read. We also changed the way the search bar looks, the padding of the each sidebar item and we added a People page. On top of that we added a dark version of the sidebar (CTRL + ?) and a minimal version (you can enable the minimal version by using the icon in the top right when hovering over the sidebar).

We also deleted the inbox item from the sidebar menu and added it in the form of a notification icon in the top right part of the sidebar.