mdb-ui-kit/scss/mixins/_buttons.scss

@mixin mdb-button-variant($color: null, $bg-color: null, $border-color: null) {
  @if ($color) {
    color: $color;
  }

  @if ($bg-color) {
    background-color: $bg-color;
  }

  @if ($border-color) {
    border-color: $border-color;
  }
}

@mixin mdb-button-color() {

  @include hover-focus {
    background-color: $mdb-btn-hover-bg;

    .theme-dark & {
      background-color: $mdb-btn-hover-bg-dark;
    }

    // reverse the above for links
    &.btn-link {
      background-color: transparent;
    }
  }

  // default
  //@include mdb-button-variant($mdb-btn-color, $mdb-btn-bg, $mdb-btn-border);

  // flat bg with text color variations
  &.btn-primary {
    @include mdb-button-variant($btn-primary-bg);
  }
  &.btn-secondary {
    @include mdb-button-variant($btn-secondary-color);
  }
  &.btn-info {
    @include mdb-button-variant($btn-info-bg);
  }
  &.btn-success {
    @include mdb-button-variant($btn-success-bg);
  }
  &.btn-warning {
    @include mdb-button-variant($btn-warning-bg);
  }
  &.btn-danger {
    @include mdb-button-variant($btn-danger-bg);
  }
}

@mixin mdb-button-colored() {

  &.btn-primary {
    @include mdb-button-variant($btn-primary-color, $btn-primary-bg, $btn-primary-border);
  }
  &.btn-secondary {
    @include mdb-button-variant($btn-secondary-color, $btn-secondary-bg, $btn-secondary-border);
  }
  &.btn-info {
    @include mdb-button-variant($btn-info-color, $btn-info-bg, $btn-info-border);
  }
  &.btn-success {
    @include mdb-button-variant($btn-success-color, $btn-success-bg, $btn-success-border);
  }
  &.btn-warning {
    @include mdb-button-variant($btn-warning-color, $btn-warning-bg, $btn-warning-border);
  }
  &.btn-danger {
    @include mdb-button-variant($btn-danger-color, $btn-danger-bg, $btn-danger-border);
  }
}

@mixin mdb-button-bg($color, $contrast: false) {
  @if ($contrast) { // contrast for focus indication
    // FIXME: SPEC - this should be the 600 color, how can we get that programmatically if at all? Or are we limited to the color palette only?
    background-color: contrast-color($color, darken($color, 4%), lighten($color, 4%));
  } @else {
    background-color: $color;
  }
}

@mixin mdb-button-colored-bg($contrast: false) {
  // default
  @include mdb-button-bg($mdb-btn-bg, $contrast);

  &.btn-primary {
    @include mdb-button-bg($btn-primary-bg, $contrast);
  }
  &.btn-secondary {
    @include mdb-button-bg($btn-secondary-bg, $contrast);
  }
  &.btn-info {
    @include mdb-button-bg($btn-info-bg, $contrast);
  }
  &.btn-success {
    @include mdb-button-bg($btn-success-bg, $contrast);
  }
  &.btn-warning {
    @include mdb-button-bg($btn-warning-bg, $contrast);
  }
  &.btn-danger {
    @include mdb-button-bg($btn-danger-bg, $contrast);
  }
}

@mixin undo-tab-focus() {
  // clear out the tab-focus() from BS
  &,
  &:active,
  &.active {
    &:focus,
    &.focus {
      //@include tab-focus();
      outline: 0;
    }
  }
}