grafana/public/sass/mixins/_forms.scss

@mixin form-control-validation($color) {
  // Color the label and help text
  .text-help,
  .form-control-label,
  .radio,
  .checkbox,
  .radio-inline,
  .checkbox-inline,
  &.radio label,
  &.checkbox label,
  &.radio-inline label,
  &.checkbox-inline label,
  .custom-control {
    color: $color;
  }

  .form-control {
    border-color: $color;
  }

  // Set validation states also for addons
  .input-group-addon {
    color: $color;
    border-color: $color;
    background-color: lighten($color, 40%);
  }
  // Optional feedback icon
  .form-control-feedback {
    color: $color;
  }
}

@mixin form-control-focus() {
  &:focus {
    border-color: $input-border-focus;
    outline: none;
    $shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 5px $input-box-shadow-focus;
    @include box-shadow($shadow);
  }
}

// Form control sizing
//
// Relative text size, padding, and border-radii changes for form controls. For
// horizontal sizing, wrap controls in the predefined grid classes. `<select>`
// element gets special love because it's special, and that's a fact!

@mixin input-size($parent, $input-height, $padding-y, $padding-x, $font-size, $line-height, $border-radius) {
  #{$parent} {
    height: $input-height;
    padding: $padding-y $padding-x;
    font-size: $font-size;
    line-height: $line-height;
    @include border-radius($border-radius);
  }

  select#{$parent} {
    height: $input-height;
    line-height: $input-height;
  }

  textarea#{$parent},
  select[multiple]#{$parent} {
    height: auto;
  }
}