Set a default sans-serif font for converse.js

css/converse.css

@@ -1150,6 +1150,7 @@
   color: #818479;
   direction: ltr;
   display: block;
+  font-family: "Helvetica", "Arial", sans-serif;
   font-size: 14px;
   height: 35px;
   position: fixed;

sass/_core.scss

@@ -4,6 +4,7 @@
     color: $text-color;
     direction: ltr;
     display: block;
+    font-family: "Helvetica", "Arial", sans-serif;
     font-size: $font-size;
     height: $bottom-gutter-height;
     position: fixed;