Bootstrap/less/labels.less

//
// Labels
// --------------------------------------------------

.label {
  display: inline;
  padding: .25em .6em;
  font-size: 75%;
  font-weight: 500;
  line-height: 1;
  color: #fff;
  text-align: center;
  white-space: nowrap;
  vertical-align: middle;
  background-color: @gray-light;
  border-radius: .25em;

  // Add hover effects, but only for links 
  &[href] {
    &:hover,
    &:focus {
      color: #fff;
      text-decoration: none;
      cursor: pointer;
      background-color: darken(@gray-light, 10%);
    }
  }
}

// Colors
// Contextual variations (linked labels get darker on :hover)
.label-danger {
  background-color: @label-danger-bg;
  &[href] {
    &:hover, 
    &:focus {
      background-color: darken(@label-danger-bg, 10%);
    }
  }
}

.label-success {
  background-color: @label-success-bg;
  &[href] {
    &:hover,
    &:focus {
      background-color: darken(@label-success-bg, 10%);
    }
  }
}

.label-warning {
  background-color: @label-warning-bg;
  &[href] {
    &:hover,
    &:focus {
      background-color: darken(@label-warning-bg, 10%);
    }
  }
}

.label-info {
  background-color: @label-info-bg;
  &[href] {
    &:hover,
    &:focus {
      background-color: darken(@label-info-bg, 10%);
    }
  }
}