fixes #9538: prevent Firefox rendering bug via some border-fu

1 files changed, 6 insertions, 1 deletions

diff --git a/less/dropdowns.less b/less/dropdowns.less
index d9417358b..53aab0267 100644
--- a/less/dropdowns.less
+++ b/less/dropdowns.less
@@ -13,6 +13,9 @@
   border-top:   @caret-width-base solid @dropdown-caret-color;
   border-right: @caret-width-base solid transparent;
   border-left:  @caret-width-base solid transparent;
+  // Firefox fix for https://github.com/twbs/bootstrap/issues/9538. Once fixed,
+  // we can just straight up remove this.
+  border-bottom: 0 dotted;
   content: "";
 }
 
@@ -161,7 +164,9 @@
 .navbar-fixed-bottom .dropdown {
   // Reverse the caret
   .caret {
-    border-top: 0;
+    // Firefox fix for https://github.com/twbs/bootstrap/issues/9538. Once this
+    // gets fixed, restore `border-top: 0;`.
+    border-top: 0 dotted;
     border-bottom: 4px solid @dropdown-caret-color;
     content: "";
   }