ionic-framework/ionic/components/button/button-clear.scss

// Clear Button
// --------------------------------------------------

button[clear],
[button][clear] {
  border-color: transparent;
  background: transparent;
  color: darken-or-lighten($button-color);

  &.activated {
    opacity: 0.4;
  }

  &:hover:not(.disable-hover) {
    opacity: 0.6;
    color: darken-or-lighten($button-color);
  }
}



// Generate Clear Button Colors
// --------------------------------------------------

@each $color-name, $color-value in auxiliary-colors() {

  $fg-color: darken-or-lighten($color-value);

  button[clear][#{$color-name}],
  [button][clear][#{$color-name}] {
    border-color: transparent;
    background: transparent;
    color: $fg-color;

    &:hover:not(.disable-hover) {
      color: darken-or-lighten($fg-color);
    }
  }

}