CSS fix.

css/converse.css

@@ -1098,9 +1098,9 @@
     opacity: 1; } }
 @-webkit-keyframes fadein {
   0% {
-    font-size: 0; }
+    opacity: 0; }
   100% {
-    font-size: 40px; } }
+    opacity: 1; } }
   #conversejs .visible {
     visibility: visible;
     opacity: 1;

sass/_core.scss

@@ -55,8 +55,8 @@
         100% { opacity: 1 }
     }
     @-webkit-keyframes fadein {
-        0% { font-size: 0 }
-        100% { font-size: 40px }
+        0% { opacity: 0 }
+        100% { opacity: 1 }
     }
 
     .visible {