node_modules/@angular/material/form-field/_form-field-theme.scss

@import '../core/theming/palette';
@import '../core/theming/theming';
@import '../core/style/form-common';
@import '../core/typography/typography-utils';

@import './form-field-fill-theme.scss';
@import './form-field-legacy-theme.scss';
@import './form-field-outline-theme.scss';
@import './form-field-standard-theme.scss';

// Color styles that apply to all appearances of the form-field.
@mixin mat-form-field-color($config-or-theme) {
  $config: mat-get-color-config($config-or-theme);
  $primary: map-get($config, primary);
  $accent: map-get($config, accent);
  $warn: map-get($config, warn);
  $background: map-get($config, background);
  $foreground: map-get($config, foreground);
  $is-dark-theme: map-get($config, is-dark);

  // Label colors. Required is used for the `*` star shown in the label.
  $label-color: mat-color($foreground, secondary-text, if($is-dark-theme, 0.7, 0.6));
  $focused-label-color: mat-color($primary, text);
  $required-label-color: mat-color($accent, text);

  // Underline colors.
  $underline-color-base: mat-color($foreground, divider, if($is-dark-theme, 1, 0.87));
  $underline-color-accent: mat-color($accent, text);
  $underline-color-warn: mat-color($warn, text);
  $underline-focused-color: mat-color($primary, text);

  .mat-form-field-label {
    color: $label-color;
  }

  .mat-hint {
    color: $label-color;
  }

  .mat-form-field.mat-focused .mat-form-field-label {
    color: $focused-label-color;

    &.mat-accent {
      color: $underline-color-accent;
    }

    &.mat-warn {
      color: $underline-color-warn;
    }
  }

  .mat-focused .mat-form-field-required-marker {
    color: $required-label-color;
  }

  .mat-form-field-ripple {
    background-color: $underline-color-base;
  }

  .mat-form-field.mat-focused {
    .mat-form-field-ripple {
      background-color: $underline-focused-color;

      &.mat-accent {
        background-color: $underline-color-accent;
      }

      &.mat-warn {
        background-color: $underline-color-warn;
      }
    }
  }

  .mat-form-field-type-mat-native-select.mat-focused:not(.mat-form-field-invalid) {
    .mat-form-field-infix::after {
      color: $underline-focused-color;
    }

    &.mat-accent .mat-form-field-infix::after {
      color: $underline-color-accent;
    }

    &.mat-warn .mat-form-field-infix::after {
      color: $underline-color-warn;
    }
  }

  // Styling for the error state of the form field. Note that while the same can be
  // achieved with the ng-* classes, we use this approach in order to ensure that the same
  // logic is used to style the error state and to show the error messages.
  .mat-form-field.mat-form-field-invalid {
    .mat-form-field-label {
      color: $underline-color-warn;

      &.mat-accent,
      .mat-form-field-required-marker {
        color: $underline-color-warn;
      }
    }

    .mat-form-field-ripple,
    .mat-form-field-ripple.mat-accent {
      background-color: $underline-color-warn;
    }
  }

  .mat-error {
    color: $underline-color-warn;
  }

  @include mat-form-field-legacy-color($config);
  @include mat-form-field-standard-color($config);
  @include mat-form-field-fill-color($config);
  @include mat-form-field-outline-color($config);
}

// Used to make instances of the _mat-form-field-label-floating mixin negligibly different,
// and prevent Google's CSS Optimizer from collapsing the declarations. This is needed because some
// of the selectors contain pseudo-classes not recognized in all browsers. If a browser encounters
// an unknown pseudo-class it will discard the entire rule set.
$mat-form-field-dedupe: 0;

// Applies a floating label above the form field control itself.
@mixin _mat-form-field-label-floating($font-scale, $infix-padding, $infix-margin-top) {
  transform: translateY(-$infix-margin-top - $infix-padding + $mat-form-field-dedupe)
             scale($font-scale);
  width: 100% / $font-scale + $mat-form-field-dedupe;

  $mat-form-field-dedupe: $mat-form-field-dedupe + 0.00001 !global;
}

@mixin mat-form-field-typography($config-or-theme) {
  $config: mat-get-typography-config($config-or-theme);
  // The unit-less line-height from the font config.
  $line-height: mat-line-height($config, input);

  // The amount to scale the font for the floating label and subscript.
  $subscript-font-scale: 0.75;
  // The amount to scale the font for the prefix and suffix icons.
  $prefix-suffix-icon-font-scale: 1.5;

  // The padding on the infix. Mocks show half of the text size.
  $infix-padding: 0.5em;
  // The margin applied to the form-field-infix to reserve space for the floating label.
  $infix-margin-top: 1em * $line-height * $subscript-font-scale;
  // Font size to use for the label and subscript text.
  $subscript-font-size: $subscript-font-scale * 100%;
  // Font size to use for the for the prefix and suffix icons.
  $prefix-suffix-icon-font-size: $prefix-suffix-icon-font-scale * 100%;
  // The space between the bottom of the .mat-form-field-flex area and the subscript wrapper.
  // Mocks show half of the text size, but this margin is applied to an element with the subscript
  // text font size, so we need to divide by the scale factor to make it half of the original text
  // size.
  $subscript-margin-top: 0.5em / $subscript-font-scale;
  // The padding applied to the form-field-wrapper to reserve space for the subscript, since it's
  // absolutely positioned. This is a combination of the subscript's margin and line-height, but we
  // need to multiply by the subscript font scale factor since the wrapper has a larger font size.
  $wrapper-padding-bottom: ($subscript-margin-top + $line-height) * $subscript-font-scale;

  .mat-form-field {
    @include mat-typography-level-to-styles($config, input);
  }

  .mat-form-field-wrapper {
    padding-bottom: $wrapper-padding-bottom;
  }

  .mat-form-field-prefix,
  .mat-form-field-suffix {
    // Allow icons in a prefix or suffix to adapt to the correct size.
    .mat-icon {
      font-size: $prefix-suffix-icon-font-size;
      line-height: $line-height;
    }

    // Allow icon buttons in a prefix or suffix to adapt to the correct size.
    .mat-icon-button {
      height: $prefix-suffix-icon-font-scale * 1em;
      width: $prefix-suffix-icon-font-scale * 1em;

      .mat-icon {
        height: $line-height * 1em;
        line-height: $line-height;
      }
    }
  }

  .mat-form-field-infix {
    padding: $infix-padding 0;
    // Throws off the baseline if we do it as a real margin, so we do it as a border instead.
    border-top: $infix-margin-top solid transparent;
  }

  .mat-form-field-can-float {
    &.mat-form-field-should-float .mat-form-field-label,
    .mat-input-server:focus + .mat-form-field-label-wrapper .mat-form-field-label {
      @include _mat-form-field-label-floating(
              $subscript-font-scale, $infix-padding, $infix-margin-top);
    }

    // Server-side rendered matInput with a label attribute but label not shown
    // (used as a pure CSS stand-in for mat-form-field-should-float).
    .mat-input-server[label]:not(:label-shown) + .mat-form-field-label-wrapper
        .mat-form-field-label {
      @include _mat-form-field-label-floating(
              $subscript-font-scale, $infix-padding, $infix-margin-top);
    }
  }

  .mat-form-field-label-wrapper {
    top: -$infix-margin-top;
    padding-top: $infix-margin-top;
  }

  .mat-form-field-label {
    top: $infix-margin-top + $infix-padding;
  }

  .mat-form-field-underline {
    // We want the underline to start at the end of the content box, not the padding box,
    // so we move it up by the padding amount.
    bottom: $wrapper-padding-bottom;
  }

  .mat-form-field-subscript-wrapper {
    font-size: $subscript-font-size;
    margin-top: $subscript-margin-top;

    // We want the subscript to start at the end of the content box, not the padding box,
    // so we move it up by the padding amount (adjusted for the smaller font size);
    top: calc(100% - #{$wrapper-padding-bottom / $subscript-font-scale});
  }

  @include mat-form-field-legacy-typography($config);
  @include mat-form-field-standard-typography($config);
  @include mat-form-field-fill-typography($config);
  @include mat-form-field-outline-typography($config);
}

@mixin mat-form-field-density($config-or-theme) {
  $density-scale: mat-get-density-config($config-or-theme);
  @include mat-private-form-field-legacy-density($density-scale);
  @include mat-private-form-field-standard-density($density-scale);
  @include mat-private-form-field-fill-density($density-scale);
  @include mat-private-form-field-outline-density($density-scale);
}

@mixin mat-form-field-theme($theme-or-color-config) {
  $theme: mat-private-legacy-get-theme($theme-or-color-config);
  @include mat-private-check-duplicate-theme-styles($theme, 'mat-form-field') {
    $color: mat-get-color-config($theme);
    $density: mat-get-density-config($theme);
    $typography: mat-get-typography-config($theme);

    @if $color != null {
      @include mat-form-field-color($color);
    }
    @if $density != null {
      @include mat-form-field-density($density);
    }
    @if $typography != null {
      @include mat-form-field-typography($typography);
    }
  }
}