Update introjs.css

Author: trantorLiu

introjs.css

@@ -77,7 +77,8 @@ tr.introjs-showElement > th {
 
 .introjs-helperLayer *,
 .introjs-helperLayer *:before,
-.introjs-helperLayer *:after {
+.introjs-helperLayer *:after,
+.introjs-helperNumberLayer {
   -webkit-box-sizing: content-box;
      -moz-box-sizing: content-box;
       -ms-box-sizing: content-box;
@@ -107,7 +108,6 @@ tr.introjs-showElement > th {
   background:         linear-gradient(to bottom, #ff3019 0%, #cf0404 100%);  /* W3C */
   width: 20px;
   height:20px;
-  box-sizing: content-box;
   line-height: 20px;
   border: 3px solid white;
   border-radius: 50%;