app/node_modules/@angular/material/form-field/_form-field-subscript.scss

@use '../core/tokens/m2/mat/form-field' as tokens-mat-form-field;
@use '../core/style/vendor-prefixes';
@use '../core/tokens/token-utils';

@mixin private-form-field-subscript() {
  @keyframes _mat-form-field-subscript-animation {
    from {
      opacity: 0;
      transform: translateY(-5px);
    }

    to {
      opacity: 1;
      transform: translateY(0);
    }
  }

  // Wrapper for the hints and error messages.
  .mat-mdc-form-field-subscript-wrapper {
    box-sizing: border-box;
    width: 100%;
    position: relative;
  }

  .mat-mdc-form-field-hint-wrapper,
  .mat-mdc-form-field-error-wrapper {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    padding: 0 16px;
    opacity: 1;
    transform: translateY(0);

    // Note: animation-duration gets set when animations are enabled.
    // This allows us to skip the animation on init.
    animation: _mat-form-field-subscript-animation 0ms cubic-bezier(0.55, 0, 0.55, 0.2);
  }

  .mat-mdc-form-field-subscript-dynamic-size {
    .mat-mdc-form-field-hint-wrapper,
    .mat-mdc-form-field-error-wrapper {
      position: static;
    }
  }

  .mat-mdc-form-field-bottom-align::before {
    content: '';
    display: inline-block;
    height: 16px;
  }

  .mat-mdc-form-field-bottom-align.mat-mdc-form-field-subscript-dynamic-size::before {
    content: unset;
  }

  .mat-mdc-form-field-hint-end {
    order: 1;
  }

  // Clears the floats on the hints. This is necessary for the hint animation to work.
  .mat-mdc-form-field-hint-wrapper {
    display: flex;
  }

  // Spacer used to make sure start and end hints have enough space between them.
  .mat-mdc-form-field-hint-spacer {
    flex: 1 0 1em;
  }

  // Single error message displayed beneath the form field underline.
  .mat-mdc-form-field-error {
    display: block;

    @include token-utils.use-tokens(tokens-mat-form-field.$prefix,
      tokens-mat-form-field.get-token-slots()) {
      @include token-utils.create-token-slot(color, error-text-color);
    }
  }

  // The subscript wrapper has a minimum height to avoid that the form-field
  // jumps when hints or errors are displayed.
  .mat-mdc-form-field-subscript-wrapper,
  .mat-mdc-form-field-bottom-align::before {
    @include token-utils.use-tokens(tokens-mat-form-field.$prefix,
      tokens-mat-form-field.get-token-slots()) {
      @include vendor-prefixes.smooth-font();
      @include token-utils.create-token-slot(font-family, subscript-text-font);
      @include token-utils.create-token-slot(line-height, subscript-text-line-height);
      @include token-utils.create-token-slot(font-size, subscript-text-size);
      @include token-utils.create-token-slot(letter-spacing, subscript-text-tracking);
      @include token-utils.create-token-slot(font-weight, subscript-text-weight);
    }
  }
}