Applied translate3d to modal, navbar-fixed and affix to combat browser repaint

less/modals.less

@@ -31,10 +31,10 @@
 
   // When fading in the modal, animate it to slide down
   &.fade .modal-dialog {
-    .translate(0, -25%);
+    .translate3d(0, -25%, 0);
     .transition-transform(~"0.3s ease-out");
   }
-  &.in .modal-dialog { .translate(0, 0)}
+  &.in .modal-dialog { .translate3d(0, 0, 0) }
 }
 
 // Shell div to position the modal with bottom padding

less/navbar.less

@@ -141,6 +141,7 @@
   right: 0;
   left: 0;
   z-index: @zindex-navbar-fixed;
+  .translate3d(0, 0, 0);
 
   // Undo the rounded corners
   @media (min-width: @grid-float-breakpoint) {

less/utilities.less

@@ -53,4 +53,5 @@
 
 .affix {
   position: fixed;
+  .translate3d(0, 0, 0);
 }