Flat Style (SASS) for select2 v3.5

select2-flat.sass

$gray: #AAA

=select2-background-active()
  background-color: #fafafa
  background-image: none
  background: #fafafa

=select2-background-white()
  background-color: #fff
  background-image: none
  background: #fff

.select2-container
  width: 100%
  margin-bottom: rem-calc(20)

  .select2-choice
    height: rem-calc(40)
    padding: rem-calc(12)
    @include select2-background-white()
    box-shadow: none
    .select2-chosen
      margin-top: 4px
    abbr
      top: 13px
    border-color: $gray

    .select2-chosen
      line-height: 1
      margin-top: 0

    .select2-arrow
      border-radius: 0
      @include select2-background-active()
      border-color: $gray
      width: 22px
      b
        background-position: -3px

        & > span
        margin: 8px 0 0 6px

  &.select2-container-active .select2-choice
    border-color: darken($gray, 30%)
  &.select2-dropdown-open .select2-choice
    border-bottom-color: #ccc

    &.select2-drop-above
      @include select2-background-active()

.select2-drop
  -webkit-border-radius: 0 !important
  border-radius: 0 !important
  &:not(.select2-drop-above)
    margin-top: -3px
  .select2-results
    max-height: 300px
    li
      line-height: inherit
      margin: 0
      padding: 0

.select2-drop-active
  box-shadow: none
  border-color: darken($gray, 30%)

.select2-search
  margin: 4px 0
  input
    @include select2-background-white()
    box-shadow: none
    margin: 0
    border: none

    &:focus
      @include select2-background-white()
      box-shadow: none
      border: none

.select2-container.form-control
  border: none
  box-shadow: none
  padding: 0