//
  // Component animations
  // --------------------------------------------------
  
  // Heads up!
  //
  // We don't use the `.opacity()` mixin here since it causes a bug with text
  // fields in IE7-8. Source: https://github.com/twitter/bootstrap/pull/3552.
  
  .fade {
    opacity: 0;
    .transition(opacity .15s linear);
    &.in {
      opacity: 1;
    }
  }
  
  .collapse {
    display: none;
    &.in {
      display: block;
    }
  }
  .collapsing {
    position: relative;
    height: 0;
    overflow: hidden;
    .transition(height .35s ease);
  }