Override conflicting rules from comments tab in Files app

Although the CSS rules for the candidate mentions of Talk no longer
mess with other elements, some too broad rules of other elements still
mess with the candidate mentions of Talk, so they need to be explicitly
overriden.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

css/At.scss

@@ -140,3 +140,11 @@
 		color: var(--color-primary-text);
 	}
 }
+
+// Override conflicting rules from the comments tab.
+.talk.candidate-mentions {
+	.atwho-view {
+		top: unset;
+		display: unset;
+	}
+}