@mixin button-base {
  $min-height: control-height();
  $vertical-padding: ($min-height - line-height(body) - rem(2px)) / 2;

  @include recolor-icon(color('ink', 'lighter'));
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: $min-height;
  min-width: $min-height;
  margin: 0;
  padding: $vertical-padding spacing();
  background: linear-gradient(
    to bottom,
    color('white'),
    color('sky', 'lighter')
  );
  border: border(dark);
  box-shadow: shadow(faint);
  border-radius: border-radius();
  line-height: 1;
  color: color('ink');
  text-align: center;
  cursor: pointer;
  user-select: none;
  text-decoration: none;
  transition-property: background, border, box-shadow;
  transition-duration: duration();
  transition-timing-function: easing();

  &:hover {
    background: linear-gradient(
      to bottom,
      color('sky', 'lighter'),
      color('sky', 'light')
    );
    border-color: color('sky', 'dark');
  }

  &:focus {
    border-color: color('indigo');
    outline: 0;
    box-shadow: 0 0 0 1px color('indigo');
  }

  &:active {
    // Same color gradient is necessary for background transitions
    background: linear-gradient(
      to bottom,
      color('sky', 'light'),
      color('sky', 'light')
    );
    border-color: color('sky', 'dark');
    box-shadow: 0 0 0 0 transparent,
      inset 0 1px 1px 0 rgba(color('ink', 'lighter'), 0.1),
      inset 0 1px 4px 0 rgba(color('ink', 'lighter'), 0.2);
  }
}

@mixin base-button-disabled {
  @include recolor-icon(color('ink', 'lightest'));
  transition: none;
  background: linear-gradient(
    to bottom,
    color('sky', 'light'),
    color('sky', 'light')
  );
  color: color('ink', 'lightest');
}

@mixin button-filled($button-color, $focus-color, $outline-color: null) {
  $border-color: darken($button-color, 10%);
  $active-color: darken($button-color, 15%);
  background: linear-gradient(
    to bottom,
    lighten($button-color, 2%),
    darken($button-color, 2%)
  );
  border-color: $border-color;
  box-shadow: inset 0 1px 0 0 lighten($button-color, 3%), shadow(faint),
    0 0 0 0 transparent;
  color: color('white');

  &:hover {
    background: linear-gradient(
      to bottom,
      $button-color,
      darken($button-color, 5%)
    );
    border-color: $border-color;
    color: color('white');
    text-decoration: none;
  }

  &:focus {
    border-color: $focus-color;
    box-shadow: inset 0 1px 0 0 lighten($button-color, 5%), shadow(faint),
      0 0 0 1px $focus-color;
  }

  &:active {
    background: linear-gradient(to bottom, $border-color, $border-color);
    border-color: $active-color;
    box-shadow: inset 0 0 0 0 transparent, shadow(faint),
      0 0 1px 0 $active-color;
  }
}

@mixin button-filled-disabled($button-color) {
  @include recolor-icon(color('white'));
  // Transition gradient to gradient to avoid flicker
  background: linear-gradient(
    to bottom,
    lighten($button-color, 25%),
    lighten($button-color, 25%)
  );
  border-color: lighten($button-color, 20%);
  box-shadow: none;
  color: color('white');
}

@mixin button-outline($outline-color) {
  background: transparent;
  border-color: rgba($outline-color, 0.4);
  box-shadow: none;
  color: darken($outline-color, 20%);

  &:hover {
    background: rgba($outline-color, 0.05);
    border-color: rgba($outline-color, 0.4);
  }

  &:focus {
    border-color: rgba($outline-color, 0.8);
    box-shadow: 0 0 0 1px rgba($outline-color, 0.8);
  }

  &:active {
    background: rgba($outline-color, 0.1);
    box-shadow: none;
  }
}

@mixin button-outline-disabled($outline-color) {
  background: transparent;
  border-color: rgba($outline-color, 0.25);
  box-shadow: none;
  color: color('ink', 'lightest');

  @include recolor-icon(color('ink', 'lightest'));
}

@mixin button-full-width {
  display: flex;
  width: 100%;
}

@function plain-button-background() {
  @return rgba(color('ink'), 0.1);
}

@mixin plain-button-backdrop() {
  position: absolute;
  top: -2px;
  bottom: -2px;
  left: -5px;
  right: -5px;
  display: block;
  background: plain-button-background();
  border-radius: border-radius();
  transition: opacity duration() easing();
}

@mixin unstyled-button() {
  appearance: none;
  margin: 0;
  padding: 0;
  background: none;
  border: none;
  font-size: inherit;
  line-height: inherit;
  cursor: pointer;

  &:focus {
    outline: none;
  }
}