framework/less/forum/NotificationsDropdown.less

.NotificationsDropdown {
  .Dropdown-menu {
    padding: 0;
    overflow: hidden;

    .NotificationList-content {
      max-height: 70vh;
      overflow: auto;
      padding-bottom: 10px;
    }
  }
  & .Dropdown-toggle .Button-label {
    margin-left: 10px;
  }
}
@media @tablet-up {
  .NotificationsDropdown {
    .Dropdown-menu {
      width: 425px;
    }
    .Dropdown-toggle {
      .Button--icon();
    }
  }
}

.NotificationsDropdown-button.unread .Button-icon {
  display: inline-block;
  border-radius: 12px;
  height: 24px;
  width: 24px;
  text-align: center;
  padding: 2px 0;
  font-weight: bold;
  margin: -2px 0;
  background: @primary-color;
  color: @body-bg;
  font-size: 13px;
  vertical-align: 0;

  & when (@config-colored-header = true) {
    background: #fff;
  }
}