//panels for chat and mailbox

.usable-height {
  height: calc(100vh - 65px);
}

.panel {
  display: flex;
  flex-direction: column;
}

.panel .panel-header, .panel .panel-footer {
  flex: 0 0 auto;
}

.panel .panel-body {
  flex: 1 1 auto;
  overflow-y: auto;
}