//
 // 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/twbs/bootstrap/pull/3552.
 
 .fade {
   opacity: 0;
   .transition(opacity .15s linear);
   &.in {
     opacity: 1;
   }
 }
 
 .collapse {
   display: none;
 
   &.in      { display: block; }
   tr&.in    { display: table-row; }
   tbody&.in { display: table-row-group; }
 }
 
 .collapsing {
   position: relative;
   height: 0;
   overflow: hidden;
   .transition-property(~"height, visibility");
   .transition-duration(.35s);
   .transition-timing-function(ease);
 }