Bad sizing with Bootstrap 3 (second attempt)

Bootstrap 3 resets the box-sizing CSS property so the Intro.js layout is broken.

introjs.css

@@ -58,6 +58,16 @@ tr.introjs-showElement > th {
           transition: all 0.3s ease-out;
 }
 
+.introjs-helperLayer *,
+.introjs-helperLayer *:before,
+.introjs-helperLayer *:after {
+  -webkit-box-sizing: content-box;
+     -moz-box-sizing: content-box;
+      -ms-box-sizing: content-box;
+       -o-box-sizing: content-box;
+          box-sizing: content-box;
+}
+
 .introjs-helperNumberLayer {
   position: absolute;
   top: -16px;