feat(frontend): Add responsive styles for channel pages

src/frontend/tau/views/channel.cljs

@@ -21,10 +21,10 @@
     [:div.flex.flex-col.items-center.px-5.py-2.flex-auto
      (if page-loading?
        [loading/loading-icon service-color "text-5xl"]
-       [:div.flex.flex-col.flex-auto {:class "ml:w-4/5"}
+       [:div.flex.flex-col.flex-auto {:class "ml:w-4/5 xl:w-3/5"}
         [navigation/back-button service-color]
         (when banner
-          [:div
+          [:div.flex.justify-center
            [:img {:src banner}]])
         [:div.flex.items-center.my-4.mx-2
          (when avatar