QuoteWidget: Add styling

gajim/data/style/gajim.css

@@ -717,7 +717,15 @@ popover.combo scrollbar.vertical {
 
 messagedialog.confirmation-dialog > box { margin-top: 18px; }
 
-
+.conversation-quote {
+    padding-bottom: 6px;
+}
+.conversation-quote textview text {
+    color: alpha(@theme_text_color, 0.6);
+}
+.conversation-quote-bar {
+    background-color: @unfocused_borders;
+}
 .conversation-more-button {
     padding-top: 0px;
     padding-bottom:0px;

gajim/gtk/conversation/quote_widget.py

@@ -18,8 +18,14 @@
 
 class QuoteWidget(Gtk.Box):
     def __init__(self, account):
-        Gtk.Box.__init__(self, orientation=Gtk.Orientation.VERTICAL)
+        Gtk.Box.__init__(self)
         self.set_vexpand(True)
+        self.get_style_context().add_class('conversation-quote')
+        quote_bar = Gtk.Box()
+        quote_bar.set_size_request(3, -1)
+        quote_bar.set_margin_right(6)
+        quote_bar.get_style_context().add_class('conversation-quote-bar')
+        self.add(quote_bar)
 
         self._account = account