Explicitly set roster items bg to white

css/converse.css

@@ -1889,6 +1889,7 @@
       border: none;
       clear: both;
       color: #818479;
+      background-color: #FCFDFD;
       display: block;
       height: 24px;
       overflow-y: hidden;

sass/_roster.scss

@@ -92,6 +92,7 @@
             border: none;
             clear: both;
             color: $text-color;
+            background-color: $light-background-color;
             display: block;
             height: 24px;
             overflow-y: hidden;