styles.css

.bslib-sidebar-layout>.sidebar>.sidebar-content {
  display: flex;
  flex-direction: column;
  padding: 1.5rem;
  padding-top: 1.5rem;
  padding-right: 1.5rem;
  padding-bottom: 1.5rem;
  padding-left: 1.5rem;
}

.shiny-notification {
  position:fixed;
  top: calc(0%);
  left: calc(50% - 150px);
}