diff -r d4ec02c51c91 -r af15590802a4 assets/stylesheets/bootstrap/_component-animations.scss
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/assets/stylesheets/bootstrap/_component-animations.scss	Thu Jun 15 12:17:09 2017 +0200
@@ -0,0 +1,37 @@
+//
+// 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;
+  @include transition(opacity .15s linear);
+  &.in {
+    opacity: 1;
+  }
+}
+
+.collapse {
+  display: none;
+
+  &.in      { display: block; }
+  // [converter] extracted tr&.in to tr.collapse.in
+  // [converter] extracted tbody&.in to tbody.collapse.in
+}
+
+tr.collapse.in    { display: table-row; }
+
+tbody.collapse.in { display: table-row-group; }
+
+.collapsing {
+  position: relative;
+  height: 0;
+  overflow: hidden;
+  @include transition-property(height, visibility);
+  @include transition-duration(.35s);
+  @include transition-timing-function(ease);
+}