Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.14)
// Compass (v1.0.1)
// ----

@mixin appearance($var) {
  -webkit-appearance: $var;
     -moz-appearance: $var;
          appearance: $var;
}

@mixin clean-select($background: white, $color: black, $height: 30px, $use-font-awesome: true) {
  height: $height;
  position: relative;
  display: inline-block;
  background: $background;
  
  &::after {
    position: absolute;
    z-index: 5;
    top: 0;
    right: 0;
    width: $height;
    height: $height;
    line-height: $height;
    text-align: center;
    pointer-events: none;
    color: $color;
    @if $use-font-awesome {
      content: "\f0d7";
      font-family: FontAwesome;
    }
    @else {
      content: "\0025BC";
    }
  }
  select {
    @include appearance(none);
    border-radius: 0;
    position: relative;
    z-index: 10;
    border: 0;
    line-height: $height;
    height: $height;
    background: transparent;
    padding: 0 $height 0 $height / 2;
    color: $color;
    cursor: pointer;
    &:focus {
      outline: 0;
      border: 0;
      &::-ms-value {
        background: transparent;
        color: $color;
      }
    }
    &:-moz-focusring {
      color: transparent;
    }
    &::-ms-expand {
      display: none;
    }
  }
  option {
    color: black;
  }
}

.select {
  @include clean-select(red, white, $use-font-awesome: false);
}

SassMeister-output.css

.select {
  height: 30px;
  position: relative;
  display: inline-block;
  background: red;
}
.select::after {
  position: absolute;
  z-index: 5;
  top: 0;
  right: 0;
  width: 30px;
  height: 30px;
  line-height: 30px;
  text-align: center;
  pointer-events: none;
  color: white;
  content: "\0025BC";
}
.select select {
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  border-radius: 0;
  position: relative;
  z-index: 10;
  border: 0;
  line-height: 30px;
  height: 30px;
  background: transparent;
  padding: 0 30px 0 15px;
  color: white;
  cursor: pointer;
}
.select select:focus {
  outline: 0;
  border: 0;
}
.select select:focus::-ms-value {
  background: transparent;
  color: white;
}
.select select:-moz-focusring {
  color: transparent;
}
.select select::-ms-expand {
  display: none;
}
.select option {
  color: black;
}