mdb-ui-kit/sass/_buttons.scss

@mixin btn-shadow(){
  @include shadow-z-1();
  transition: box-shadow 0.28s cubic-bezier(0.4, 0, 0.2, 1);
  &:active:not(.btn-link) {
    @include shadow-z-1-hover();
  }
}

.btn {
  position: relative;
  padding: 8px 30px;
  border: 0;
  margin: 10px 1px;
  cursor: pointer;
  border-radius: 2px;
  text-transform: uppercase;
  text-decoration: none;
  color: $darkbg-text;

  &:hover:not(.btn-link):not(.btn-flat):not(.btn-fab) {
    @include shadow-z-1();
  }
  &:active:not(.btn-link):not(.btn-flat):not(.btn-fab) {
    @include shadow-z-1-hover();
  }
  transition: background-color 0.2s ease, box-shadow 0.28s cubic-bezier(0.4, 0, 0.2, 1);
  outline: none !important;


  @include variations(unquote(".btn-flat:not(.btn-link)"), color, $lightbg-text);

  @include background-variations(unquote(":not(.btn-link):not(.btn-flat)"), $btn-default);

  // BTN hover effect
  @include button-variations(unquote(":hover:not(.btn-link):not(.btn-flat)"), $btn-default, 4%);
  // BTN active effect
  @include button-variations(unquote(":active:not(.btn-link):not(.btn-flat)"), $btn-default, 6%);
  // BTN .active effect
  @include button-variations(unquote(".active:not(.btn-link):not(.btn-flat)"), $btn-default, 6%);
  // BTN flat hover effect
  @include bg-color-variations(unquote(".btn-flat:hover:not(.btn-link)"), $btn-default, (20/100));

}

.btn {
  &.btn-flat {
    background: none;
    box-shadow: none;
    font-weight: 500;
    &:disabled {
      color: $text-disabled !important;
    }
  }

  // Size variations
  &.btn-sm {
    padding: 5px 20px;
  }
  &.btn-xs {
    padding: 4px 15px;
    font-size: 10px;
  }

  &.btn-raised {
    @include btn-shadow();
  }

  &.btn-fab {
    margin: 0;
    padding: 15px;
    font-size: 26px;
    width: 56px;
    height: 56px;
    &, &:hover, &:active {
      @include variations(unquote(""), background-color, transparent);
    }
    &, &:hover {
      @include shadow-z-1();
    }
    &:active {
      @include shadow-z-1-hover();
    }
    &, .ripple-wrapper {
      border-radius: 100%;
    }
    &.btn-fab-mini {
      width: 40px;
      height: 40px;
      padding: 13px 0;
      font-size: 15px;
    }
    i {
      position: relative;
      top: -5px;
      margin: 0 auto;
    }
  }
}

// This is needed to style buttons which has not a variation suffix (they must be stiled as btn-default)
.btn-link, .btn:not([class*="btn-"]), .btn-default {
  color: $lightbg-text;
  &:hover {
    color: $lightbg-text;
  }
}
.btn:not([class*="btn-"]), .btn-default, .btn-flat:not(.btn-link) {
  &:hover, &.active {
    background-color: rgba(255,255,255,0.5);
  }
}
.open > .dropdown-toggle.btn {
  @include variations(unquote(""), background-color, $btn-default);
}
.btn-group .btn+.btn, .btn-group .btn+.btn-group, .btn-group .btn-group+.btn, .btn-group .btn-group+.btn-group {
  margin-left: 0;
}
.btn-group, .btn-group-vertical {
  position: relative;
  border-radius: 2px;
  margin: 10px 1px;

  @include btn-shadow();
  &.open .dropdown-toggle {
    box-shadow: none;
  }
  &.btn-group-raised {
    @include btn-shadow();
  }
  .btn, .btn:active, .btn-group {
    box-shadow: none !important;
    margin: 0;
  }
}
.btn-group-flat {
  box-shadow: none !important;
}