discourse/app/assets/stylesheets/common/select-kit/pinned-button.scss

#topic-footer-buttons {
  .pinned-button {
    min-width: auto;
    margin: 1em 0;

    &.is-hidden {
      display: none;
    }

    .btn {
      margin: 0;
    }

    .reason {
      display: inline;
      line-height: $line-height-medium;
    }
  }
}

.pinned-button {
  margin: 0;
  min-width: auto;

  .pinned-options {
    display: inline;

    .select-kit-body {
      min-width: unset;
      max-width: unset;
      width: 550px;
    }
  }
}