feat: remove border radius on small clamp

data/app.css

@@ -5,6 +5,10 @@
   color: @text_view_bg;
 }
 
+.small .ttl-content {
+  border-radius: 0px;
+}
+
 .attachment, .attachment button, flowboxchild {
 	padding:0px;
 	margin:0px;

src/Views/ContentBase.vala

@@ -19,6 +19,7 @@ public class Tootle.Views.ContentBase : Views.Base {
 		};
 		content_box.append (content);
 		content.add_css_class ("content");
+		content.add_css_class ("ttl-content");
 		content.row_activated.connect (on_content_item_activated);
 
 		content.bind_model (model, on_create_model_widget);