Bootstrap 3.2 button outline style and outline style on inverse background

buttons-outline.scss

// Button outline style
.btn-outline {
    background-color: transparent;
}

.btn-primary.btn-outline {
    color: $btn-primary-bg;
    $:hover {
      background-color: $btn-primary-bg;
          border-color: $btn-primary-border;
    }
}

.btn-success.btn-outline {
    color: $btn-success-bg;
    $:hover {
      background-color: $btn-success-bg;
          border-color: $btn-success-border;
    }
}

.btn-info.btn-outline {
    color: $btn-info-bg;
    $:hover {
      background-color: $btn-info-bg;
          border-color: $btn-info-border;
    }
}

.btn-warning.btn-outline {
    color: $btn-warning-bg;
    $:hover {
      background-color: $btn-warning-bg;
          border-color: $btn-warning-border;
    }
}

.btn-danger.btn-outline {
    color: $btn-danger-bg;
    $:hover {
      background-color: $btn-danger-bg;
          border-color: $btn-danger-border;
    }
}

.btn-primary.btn-outline:hover,
.btn-success.btn-outline:hover,
.btn-info.btn-outline:hover,
.btn-warning.btn-outline:hover,
.btn-danger.btn-outline:hover {
    color: #fff;
}

// Button outline style on inverse background
.btn-outline-inverse {
    background-color: transparent;
    border-color: #fff;
    color: #fff;
    $:hover {
      background-color: #fff;
    }
}
.btn-primary.btn-outline-inverse:hover {
    color: $brand-primary;
}

.btn-success.btn-outline-inverse:hover {
    color: $brand-success;
}

.btn-info.btn-outline-inverse:hover {
    color: $brand-info;
}

.btn-warning.btn-outline-inverse:hover {
    color: $brand-warning;
}

.btn-danger.btn-outline-inverse:hover {
    color: $brand-danger;
}