open-vault/ui/app/styles/core/menu.scss

.column .menu-list a {
  border-radius: 0;
  border-right: 0 solid transparent;
  font-weight: $font-weight-semibold;

  &:hover,
  &.is-active {
    color: $menu-item-active-color;
    background-color: $menu-item-active-background-color;
  }
}