discourse/app/assets/stylesheets/common/components/dropdown-select-box.scss

.dropdown-select-box.dropdown-select-box {
  display: inline-flex;
  height: 30px;
  min-width: auto;

  &.is-expanded {
    z-index: 9999;

    .collection,
    .select-box-collection,
    .select-box-body {
      border-radius: 0;
    }
  }

  .select-box-body {
    border: 1px solid dark-light-diff($primary, $secondary, 90%, -60%);
    background-clip: padding-box;
    box-shadow: 0 1px 5px rgba(0,0,0,0.4);
    width: max-content;
    max-width: 300px;
  }

  .select-box-row {
    margin: 0;
    padding: 5px 10px;

    .icons {
      display: flex;
      align-items: flex-start;
      justify-content: space-between;
      align-self: center;
      margin-right: 10px;

      .d-icon {
        font-size: 1.286em;
        align-self: center;
        margin-right: 0;
        opacity: 1;
      }
    }

    .texts {
      line-height: 18px;
      flex: 1;
      align-items: flex-start;
      display: flex;
      flex-wrap: wrap;
      flex-direction: column;

      .title {
        flex: 1;
        font-weight: bold;
        display: block;
        font-size: 1em;
        color: $primary;
      }

      .desc {
        flex: 1;
        font-size: 0.857em;
        font-weight: normal;
        color: dark-light-choose(scale-color($primary, $lightness: 50%), scale-color($secondary, $lightness: 40%));;
        white-space: normal;
      }
    }

    &.is-highlighted {
      background: none;
    }

    &:hover {
      background: $highlight-medium;
    }
  }

  .select-box-collection {
    padding: 0;
  }

  .dropdown-header {
    padding: 0;
    border: 0;
    outline: 0;
    justify-content: flex-start;
    width: max-content;
    background: none;

    .d-icon + .d-icon {
      margin-left: 5px;
    }

    .btn {
      align-items: center;
      justify-content: space-between;
      flex-direction: row;
      display: inline-flex;
      height: 100%;
      margin: 0;
    }
  }
}