Bootstrap 3 RC1

assets/less/bootstrap/component-animations.less

@@ -2,6 +2,10 @@
 // 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;
@@ -12,11 +16,14 @@
 }
 
 .collapse {
+  display: none;
+  &.in {
+    display: block;
+  }
+}
+.collapsing {
   position: relative;
   height: 0;
   overflow: hidden;
   .transition(height .35s ease);
-  &.in {
-    height: auto;
-  }
 }