feat(threads): thread and forum UI on web (#3252)

fluxer_app/src/features/channel/components/ChannelHeader.module.css

@@ -501,6 +501,25 @@
 	max-width: 15.25rem;
 }
 
+.headerContainerThreadPanelOpen {
+	grid-template-columns: minmax(min(12rem, 40%), 1fr) minmax(0, auto);
+}
+
+.headerContainerThreadPanelOpen .topicDivider,
+.headerContainerThreadPanelOpen .topicContainer {
+	display: none;
+}
+
+.headerContainerThreadPanelOpen .messageSearchFocusWrapper {
+	flex: 0 1 15.25rem;
+	min-width: 9rem;
+}
+
+.headerContainerThreadPanelOpen .messageSearchFocusWrapper > :first-child {
+	width: 100%;
+	min-width: 0;
+}
+
 .iconButton {
 	display: flex;
 	align-items: center;