Make private chats wider

sass/_variables.scss

@@ -169,7 +169,7 @@ $mobile_portrait_length: 480px !default;
 
     --overlayed-chat-head-height: 55px;
     --overlayed-chat-height: 450px;
-    --overlayed-chat-width: 250px;
+    --overlayed-chat-width: 300px;
     --overlayed-chatbox-hover-height: 1em;
     --overlayed-emoji-picker-height: 200px;
     --overlayed-max-chat-textarea-height: 200px;