_bootstrap5.scss

.twitter-typeahead {
  display: block !important;

  .dropdown-item {
    cursor: default;
  }
}

.input-group {
  > .twitter-typeahead {
    position: relative; // For focus state's z-index
    flex: 1 1 auto;
    width: 1%;
    min-width: 0; // https://stackoverflow.com/questions/36247140/why-dont-flex-items-shrink-past-content-size
  }

  // Bring the "active" form control to the top of surrounding elements
  > .twitter-typeahead:focus-within {
    z-index: 5;
  }

  &:not(.has-validation) {
    > .twitter-typeahead:not(:last-child) > .form-control {
      @include border-end-radius(0);
    }
  }

  &.has-validation {
    > .twitter-typeahead:nth-last-child(n + 3) > .form-control {
      @include border-end-radius(0);
    }
  }

  > .twitter-typeahead:not(:first-child) > .form-control {
    @include border-start-radius(0);
  }
}

.input-group-lg > .twitter-typeahead:not(.form-floating) {
  > .form-control {
    padding: $input-padding-y-lg $input-padding-x-lg;
    @include font-size($input-font-size-lg);
    @include border-radius($input-border-radius-lg);
  }

  .dropdown-item {
    @include font-size($input-font-size-lg);
  }
}

.input-group-sm > .twitter-typeahead:not(.form-floating) {
  > .form-control {
    padding: $input-padding-y-sm $input-padding-x-sm;
    @include font-size($input-font-size-sm);
    @include border-radius($input-border-radius-sm);
  }

  .dropdown-item {
    @include font-size($input-font-size-sm);
  }
}