!important use case

example.scss

  .input-group-btn > .btn {
    background-color: $white;
    border-color: $white;
    border-left-color: $well-bg !important;

    &:hover {
      background-color: $gray-superlight;
      border-color: $gray-superlight;
    }

    &:active,
    &:focus {
      background-color: $misty;
      border-color: $misty;
    }