gitlab-org--gitlab-foss/app/assets/stylesheets/selects.scss

/** Chosen.js selectbox style override **/
.chosen-container {
  min-width: 100px;

  .chosen-single {
    background: #EEE !important;
    border: 1px solid #DDD !important;
    @include box-shadow(none !important);
    @include border-radius(4px !important);
  }

  .chosen-results li.highlighted {
    background: #29b;
  }

  .chosen-drop {
    margin-top: 10px;
    border: 1px solid #DDD !important;
    @include border-radius(4px !important);
  }

  .chosen-search input {
    border: 1px solid #CCC !important;
    @include box-shadow(none !important);
  }
}

/** Select2 styling **/
.select2-container .select2-choice {
  @include bg-light-gray-gradient;
}

.select2-container .select2-choice div {
  border: none;
  background: none;
}

.select2-drop {
  padding-top: 8px;
}

.select2-no-results, .select2-searching {
  padding: 7px;
  color: #666;
}

.chosen-container .chosen-single div b {
  background-position-y: 0px !important;
}

.chosen-container .chosen-drop .chosen-search input {
  background-position-y: -24px !important;
}