"sidebar-link">Contributing</a></li></ul></div></li><li><div class="sidebar-group"><p class="sidebar-heading"><span>User Interface</span> <!----></p> <ul class="sidebar-group-items"><li><a href="/docs/user-interface/overview.html" class="sidebar-link">Overview</a></li></ul></div></li><li><div class="sidebar-group"><p class="sidebar-heading open"><span>Reference</span> <!----></p> <ul class="sidebar-group-items"><li><a href="/docs/reference/activity.html" class="sidebar-link">Activity</a></li><li><a href="/d